Proceedings doi: 10.3390/proceedings2026146079

Authors: Sara Lourenço Catarina N. S. Silva Miguel A. Pardal Paolo Momigliano André S. Afonso Filipe Martinho

Introduction: Skates (Rajidae) are cornerstone elasmobranchs, yet their intrinsic biological constraints, like slow growth, late maturation, and low fecundity, render them exceptionally susceptible to anthropogenic pressure. Despite their ecological and economic importance, tracking their population trajectories is historically hindered by “taxonomic blurring” and aggregated reporting in commercial fisheries. Objective: This study evaluates long-term conservation trends and exploitation dynamics of Rajidae species in the Northeast Atlantic and the Mediterranean Sea. Methodology: We analyzed 31 Rajidae species across the Northeast Atlantic and the Mediterranean Sea (FAO Areas 27 and 37) by integrating IUCN Red List assessments, species-specific life-history traits (maximum body size and depth distribution), and FAO fisheries landing data from 1992 to 2023. Descriptive analyses and Spearman correlations were used to assess temporal trends in conservation status and exploitation patterns. Results: Our synthesis reveals that some species show improvements in IUCN Red List category assessments, likely driven by recent management interventions such as species-specific reporting, catch quotas, and targeted retention bans. However, we also identify a critical mismatch between policy and biology: current Total Allowable Catches (TACs) and minimum landing sizes often do not explicitly incorporate species-specific life-history traits, inadvertently favoring smaller, less-marketable taxa while leaving larger, vulnerable species at risk. While FAO landings offer a valuable broad-scale overview of exploitation, the results highlight the limitations of aggregated fisheries statistics for species-level conservation assessments. Conclusions: These findings underline the need to adopt more precise and species-specific fisheries management approaches for Rajidae, including expanded regional monitoring programs, the use of data collected by on-board observers or electronic monitoring tools, and improved control of data reporting procedures, to prevent continued aggregation of species-level data.

Proceedings doi: 10.3390/proceedings2026146077

Authors: José Maria Santos Paulo Branco Maria João Costa Ana Filipa Filipe

Introduction: The Guadiana basin harbours one of the most threatened freshwater fish faunas in Europe, concentrating a high number of Iberian endemisms and species of high conservation interest. Among these, the Iberian minnowcarp (Anaecypris hispanica) and the Iberian Arched-Mouth Nase (Iberochondrostoma lemmingii) stand out as threatened species whose populations are in serious decline. Methodology: In March 2023, an obsolete river barrier, the Galaches weir, was removed from the Odeleite River (Guadiana basin), releasing an 8 km lotic stretch previously inaccessible to downstream fish fauna. This study aimed to evaluate the effects of weir removal on the composition and structure of the fish community, using a Before-After design with fish sampling conducted before (2022) and after (2024) weir removal. Fish sampling took place in early summer by means of electrofishing in two 150 m long river sites, one upstream and one downstream of the weir. Results: Before removal, both upstream and downstream sites were dominated by native leuciscids (A. hispanica, I. lemmingii, Squalius pyrenaicus, and Pseudochondrostoma willkommii) and cyprinids (Luciobarbus spp.), with non-natives Lepomis gibbosus and Australoheros facetus occurring in lower abundance. After removal, native species remained clearly dominant at both sites, while A. facetus was no longer detected and L. gibbosus did not increase in abundance, suggesting that barrier removal did not favour the spread of non-native fish. Species size–structure revealed the presence of multiple size classes, possibly supporting a regular recruitment of key native taxa: A. hispanica occurred almost exclusively with total lengths of 4 to 6 cm, whereas I. lemmingii and other native leuciscids displayed broader size ranges, spanning juveniles to adults, consistent with sustained reproduction and growth in the restored river stretch. Conclusions: These findings support the hypothesis that weir removal has improved the sustainability of native fish populations such as A. hispanica by improving habitat connectivity and increasing recruitment. The results highlight the importance of weir removal for the conservation of threatened species in Mediterranean river systems.

Proceedings doi: 10.3390/proceedings2026146075

Authors: Amílcar Teixeira Ryan Alves da Silva Douglas Santos Fernando Miranda Fernando Teixeira

Mediterranean rivers experience various pressures that cause native fish populations to decline. This is the case of Achondrostoma asturicense, a threatened endemic species recently classified as "endangered" (EN) by the Portuguese Red Book. In northeastern Portugal, the main populations occur in the Carvalhais (Tua basin), Maçãs, and Angueira (Sabor basin) rivers. This study aimed to evaluate the effect of small weirs on the distribution, abundance, and habitat use of A. asturicense populations along the longitudinal gradient of River Angueira. Three river zones (Z1 to Z3) affected by small weirs were selected along the watercourse. In each zone, four sampling sites were distributed relative to the weir, as follows: A1—200 m downstream; A2—immediately downstream; A3—under the influence of the reservoir; and A4—200 m upstream (reference). Sampling was carried out in three seasons: winter, spring, and summer 2025. Physical–chemical (water), hydromorphological (habitats), and biological (fish) elements were assessed in accordance with the protocols of the Water Framework Directive. The results revealed the worst water quality in the summer season due to flow reduction, dissolved oxygen depletion, elevated conductivity, and high nutrient (N, P) concentrations, leading to eutrophication phenomena. The distribution and abundance of A. asturicense were negatively influenced by the presence of small weirs, which were dominated by the non-native species Lepomis gibbosus. PERMANOVA analysis (two-way, p < 0.05) identified significant differences (Pseudo-F = 28.349, p < 0.05) between sampling sites and river zones, and paired similarity analysis tests (ANOSIM; one-way, p < 0.05) confirmed that these differences occur only between the weir reservoir (A3) and the remaining sampling sites. A. asturicense showed a maximum length (Lmax) of 135 mm, isometric growth only in the upstream zone (Z1), and significant differences in body condition (0.75 < K < 0.84). This species showed a preference for rheophilic habitats, with coarse substrate and diversity of currents and distinct cover mainly guaranteed by submerged aquatic macrophytes. A. asturicense populations are severely affected in the River Angueira by habitat fragmentation, riparian degradation, pollution, invasive alien species (e.g., L. gibbosus, P. clarkii, N. vison), and climate change, justifying the development of mitigation and restoration measures for the conservation of natural habitats and native threatened species.

Proceedings doi: 10.3390/proceedings2026146078

Authors: Zoé Lemoine André Gomes-dos-Santos David Barros-García

Elopomorpha is one of the most primitive teleost lineages and is characterised by a unique trait, the leptocephalus larva. Its leaf-like and transparent body is largely composed of glycosaminoglycan (GAG), which makes it distinctive from other fish larvae. Hyaluronic acid (HA) has been identified as the principal GAG present in these larvae and is thought to play several physiological roles, such as floatability, osmoregulation, and energy storage. During the larval stage, HA reaches a concentration of up to 40 to 50% of the body composition due to a HA synthesis peak. Later in metamorphosis, HA concentration decreases and, after this, adults show a normal HA metabolism. These observations could be explained if the larva has an alternative HA metabolism compared to the adult. It is known that HA synthesis is done by three hyaluronan synthase (HAS) enzymes, which differ in the length of HA synthetized, codified by three genes: HAS1, HAS2 and HAS3. Therefore, to test the hypothesis of a larval-specific metabolism, the genomic basis of these genes in Elopomorpha will be analysed. To this end, HAS coding and protein sequences from nine Elopomorpha, four Osteoglossomorpha and 21 Clupeocephala species were mined from the NCBI database to ensure a broad phylogenetic coverage. To guarantee a complete retrieval of HAS genes, the BLAST tool (https://blast.ncbi.nlm.nih.gov/Blast.cgi, accessed on 1 March 2026) and synteny analysis were performed. Then, Pseudochecker was used to confirm the functionality of the candidate genes obtained. Functional genes were used for phylogenetic analyses, maximum likelihood and Bayesian inference to test orthology. Both lineage and species duplications of HAS1 and HAS2 were found in Elopomorpha, which would be responsible for the synthesis of HA during the larval stage. These new genetic patterns provide the first evidence of a possible alternative metabolism of HA during the larval stage of Elopomorpha.

Proceedings doi: 10.3390/proceedings2026146076

Authors: Marina Martínez-Miguel Ana García-Vega Francisco Javier Bravo-Córdoba Francisco J. Sanz-Ronda Juan Francisco Fuentes-Pérez

Introduction: River fragmentation caused by hydropower infrastructure remains a primary threat to aquatic biodiversity, creating a critical need for fish passage solutions that can adapt to high environmental variability. Although adaptive management (AM) has the potential to significantly improve longitudinal connectivity and ecological resilience, its application in real-world fishway operations is currently limited. Objective: This study aims to present and validate a flexible AM framework designed to optimize fish passage by integrating low-cost monitoring systems with automated data processing and predictive modeling. Methodology: The proposed system combines a sensor network for real-time water-level and environmental monitoring with biological performance data obtained through Passive Integrated Transponder (PIT) technology. These data were processed locally using edge computing. Over a two-year period, weekly aggregated data were used to develop Random Forest models to identify the primary drivers of fish movement. Results: The final model successfully identified five key drivers: luminosity, water temperature, and three nested hydraulic parameters at the fishway’s upstream section. Validation at a vertical-slot fishway in Vadocondes (Duero River, Spain) showed that retrospective optimization—specifically adjusting sluice-gate regulation—could increase downstream water levels and reduce drops at the first cross wall. This adjustment demonstrated a substantial increase in predicted fish passage without requiring changes to the hydropower plant’s core operation. Conclusions: The framework is highly flexible and transferable to other regulated river systems. However, its success is contingent upon the definition of clear ecological objectives and the seamless integration of monitoring results into the day-to-day operation of river infrastructure.

Proceedings doi: 10.3390/proceedings2026146074

Authors: David Barros-García André Gomes-dos-Santos André M. Machado Francisco Baldó

The vertebrate mitochondrial genome (mitogenome) is a small, circular DNA molecule typically ~16–17 kb in length, encoding 37 genes that are essential for the electron transport chain, the mechanism that drives mostly all the ATP synthesis in cells. Owing to its central role in energy metabolism, its structure is highly conserved across vertebrate lineages in both the number and relative position of each gene in the genome. Nevertheless, different variations have been found in several teleost lineages, including antarctic fishes (Nototheniidae), gadiforms, hatchetfishes (Sternoptychidae), and Batrachoidiformes. The explanation for these phenomena remains unknown yet may reflect shifts in functional constraints and can provide insights into lineage-specific and/or coevolutionary processes. This raises the possibility that mitogenome structure is related to habitat selection, potentially reflecting environmental influences on energetic regulation. To further test this hypothesis, we studied more than 400 teleost species across all major teleost lineages. The mitogenome sequences were downloaded from NCBI and annotated using two independent algorithms (MITOZ and MITOS) and then compared with a reference (Danio rerio) to find any deviation from the standard structure. Similarly, ecological data was downloaded from FishBase using the R Package “rfishbase” 5.0.3. Two independent ancestral reconstruction analyses were carried out for both traits, “Mitogenome” and “Habitat”, using a reference evolutionary tree for teleosts to unravel both evolutionary histories. The possible association between mitogenome and habitat was then assessed using a suite of phylogenetic comparative methods, including Pagel’s correlation test (corHMM) to evaluate whether both traits evolved in a correlated fashion, branch-level co-transition analysis to identify lineages where structural changes and habitat shifts co-occurred, and node-by-node comparisons of ancestral state probabilities across the phylogeny. Preliminary results suggest a correlation between some deep-sea environments and a modified mitogenome structure, with structural deviations tending to cluster in lineages inhabiting greater depths. These exploratory findings raise the possibility that changes in mitogenome architecture may be linked to adaptations in energetic metabolism required for life in extreme low-energy environments. Further analyses are underway to clarify the functional significance of these genomic changes and their relationship to ecological and metabolic pressures in teleost evolution.

Proceedings doi: 10.3390/proceedings2026146073

Authors: Ana Filipa Filipe Janine da Silva Virgilio Hermoso

Introduction: Species Distribution Models (SDMs) are widely used to infer environmental drivers of freshwater fish distributions and to project biodiversity responses to climate and land-use change. However, freshwater ecosystems present specific conceptual and methodological challenges, including dendritic network structure, strong spatial autocorrelation, dispersal constraints, and scale mismatches between biological processes and environmental predictors that remain insufficiently addressed. At the same time, emerging data sources such as environmental DNA (eDNA) and high-resolution remote sensing offer new opportunities to improve data coverage and ecological realism in SDMs. Methodology: Focusing on Iberian systems as illustrative case studies, here, we synthesize the following recent advances and challenges in SDM applications to freshwater fishes: (i) the implications of using presence–absence versus abundance data; (ii) the integration of hydrological and connectivity metrics as predictors; (iii) approaches to explicitly account for spatial structure and biotic interactions; and (iv) the contribution of novel datasets, including eDNA and remote sensing. Furthermore, we examine the performance and transferability of correlative models under analogue and non-analogue climate conditions. Results: Our synthesis highlights the importance of incorporating network topology, seasonality, dispersal constraints, and novel data sources to improve ecological realism and predictive performance. The integration of emerging biodiversity and environmental data can substantially reduce data gaps and improve model calibration and validation, particularly in poorly sampled systems. Nonetheless, model transferability remains a challenge, particularly for endemic and range-restricted species. Advancing freshwater SDMs through the integration of hydrologically explicit frameworks and novel data sources will strengthen their capacity to support evidence-based management of freshwater fish assemblages facing accelerating environmental changes.

Proceedings doi: 10.3390/proceedings2026146064

Authors: Ana Filipa Filipe Maria João Costa Arthur Cupertino Maria Teresa Ferreira Daniel Mameri Patricia María Rodríguez-González José M. Santos Catarina Grilo José Pedro Ramião João Oliveira

Introduction: AQUArestore is a three-year project focused on promoting adaptive ecological restoration strategies for river ecosystems in the vulnerable cross-border region of Portugal. The project responds to pressing environmental challenges across the territory, including severe habitat degradation, climate vulnerability, declining water security, and biodiversity loss, with particular concern for freshwater fish communities, making river restoration essential to preserve native species and freshwater ecosystem services. Objective: The project aims to develop a replicable framework for restoration of Mediterranean transboundary riverine habitats, supporting the objectives of the EU Nature Restoration Law (NRL, Regulation 2024/1991). The consortium AQUArestore will develop (1) robust restoration indicators, (2) implement living labs for restoration experimentation, and (3) establish capacity-building and training programs for technicians and citizens. Methodology: The project kick-off meeting was used to operationalize project tasks, detail the implementation calendar and milestones, and clarify responsibilities of each project member and partner institutions within the different work tasks. The meeting gathered consortium members from the coordinating institution CEF-ISA (researchers at the Instituto Superior de Agronomia) and partners WWF Portugal (an environmental NGO) and Mushmore Cooperative, each one contributing according to their respective expertise and institutional objectives. Results: The AQUArestore project kick-off meeting took place in January 2026 at ISA, Lisbon, and included a presentation of the NRL and a detailed discussion of project task development. In detail, the activities will begin with the compilation of information on previously restored sites (Task 1). This will support the development and validation of environmental and biodiversity indicators of restoration outcomes, including those linked to freshwater fish assemblages and riparian vegetation (Task 2). The project will then establish two living labs as platforms to test nature-based solutions in collaboration with stakeholders and local communities (Task 3). In parallel, AQUArestore will strengthen technical capacity through training for practitioners and public authorities (Task 4). Finally, dissemination will be supported through citizen science, communication activities, and stakeholder engagement, fostering a broader impact (Task 5). Together, these tasks provide an integrated, science-based, and participatory framework aiming to support adaptive river restoration under climate and environmental changes. Conclusions: By integrating ecological restoration, biodiversity and environmental monitoring, and stakeholder engagement, AQUArestore is expected to contribute to the recovery of Mediterranean freshwater ecosystems and improve habitat quality and connectivity for native fish communities, enhancing resilience to climate change and other anthropogenic pressures.

Proceedings doi: 10.3390/proceedings2026146067

Authors: Amândio de Barros Diana Santos Tiago Lourenço Célia Lopes Tânia Vieira Madureira Eduardo Rocha

Introduction: The liver is a central metabolic regulator responsible not only for energy storage and allocation but also for the production of essential egg proteins. In seasonal breeders such as brown trout, physiological demands increase during spawning, requiring strong metabolic and structural adaptations. Understanding the cellular mechanisms underlying these fluctuations is essential for clarifying how liver function is regulated during reproduction. Objective: The aim of this study was to investigate cellular mechanisms underlying liver remodelling during the reproductive cycle of male and female brown trout by examining proliferation and apoptosis markers at both molecular and protein levels during four distinct reproductive stages: spawning capable, regressing, regenerating, and developing. Methodology: Adult male and female brown trout were sampled at four reproductive stages. Liver gene expression of proliferating cell nuclear antigen (PCNA) and caspase-3 was analysed using qRT-PCR. At the protein level, liver tissue sections were immunolabelled with antibodies against PCNA and caspase-3. Caspase-3 staining intensity was quantified using ImageJ, while PCNA expression was assessed by counting positively stained nuclei. Results: PCNA gene expression was upregulated during the regressing stage, while PCNA-positive nuclei immunolabelling increased during the regressing and spawning-capable stages. Caspase-3 transcript levels showed no significant differences among stages, whereas immunostaining increased during regenerating and developing stages. Conclusions: Overall, the liver undergoes dynamic cellular remodelling throughout the reproductive cycle, balancing proliferation and apoptosis to meet reproductive demands. The results suggest that proliferation is more evident during regenerating stages, while apoptotic activity may be regulated post-transcriptionally. PCNA also indicates that proliferative activity may persist during spawning capable stages, reflecting ongoing mitotic readiness despite reduced overall proliferation.

Proceedings doi: 10.3390/proceedings2026146063

Authors: Rodrigo Alves Célia Lopes Rosária Seabra Sofia Esquível Maria J. Rocha Eduardo Rocha Tânia Vieira Madureira

Introduction: Temperature is a key environmental factor influencing the physiological and biochemical processes of aquatic organisms, including xenobiotic metabolism. Understanding how temperature modulates the toxicological effects of pollutants such as polycyclic aromatic hydrocarbons (PAHs) is crucial in the context of climate change. Among these compounds, benzo[a]pyrene (BaP) and benzo[a]anthracene (BaA) are priority pollutants in aquatic environments, resulting from incomplete combustion. Their relevance is attributed to persistence and metabolic bioactivation potential. Fish primary hepatocyte cultures represent a relevant in vitro model for studying combined effects of thermal stress and chemical exposures, while supporting the 3Rs principles (Replacement, Reduction, and Refinement). Objective: This study aims to assess temperature-dependent effects of BaP and BaA, and their mixtures in brown trout hepatocytes using cytochrome P450 1A (CYP1A) immunohistochemistry as an indicator of xenobiotic metabolism. Methodology: Primary hepatocytes were isolated using a two-step collagenase perfusion method and cultured in 24-well plates at 18 °C and 22 °C. Cells were exposed for 72 h to supplemented L-15 medium (control) or to 0.1% dimethyl sulfoxide in supplemented L-15 medium (solvent control), as well as to single exposures of 1 and 10 µM of BaP and BaA and to equimolar mixtures of both compounds (1 and 10 µM). Viability was assessed using the lactate dehydrogenase (LDH) assay. CYP1A immunostaining was quantified based on cytoplasmic staining intensity relative to background area. Results: No significant effects on cell viability were observed under any condition. Temperature significantly reduced CYP1A expression in single exposures at 22 °C compared to 18 °C. BaP induced a significant dose-dependent increase, while BaA differed from controls only at 10 µM. In mixtures, only treatment- and dose-dependent effects were observed, with no temperature influence detected. Conclusions: Overall, the data highlight temperature as a key modulator of biochemical responses to PAHs, with single and mixed exposures eliciting distinct effects and suggesting potential synergism in mixtures.

Proceedings doi: 10.3390/proceedings2026146071

Authors: Ariana Pérez-Pereira Ondina Ribeiro Luís Félix Maria Tiritan Cláudia Ribeiro João Carrola

Introduction: Synthetic cathinones (SC) are an emerging class of neuroactive contaminants increasingly detected in aquatic systems due to their widespread recreational use. Their continuous release at ng–µg L−1 levels is particularly concerning, as these compounds are specifically designed to alter neural function, raising the likelihood of subtle yet ecologically relevant effects in non-target organisms. Among them, 3,4-methylenedioxypyrovalerone (MDPV) is one of the most-reported SC in wastewater and surface waters. Nevertheless, its chiral nature has been largely overlooked in ecotoxicological studies, despite growing evidence that enantiomers can differ markedly in biological activity, potentially leading to underestimated environmental risks. Objective: The ecotoxicological impact of racemic MDPV ((R,S)-MDPV) and its separate enantiomers ((R)-MDPV and (S)-MDPV) were examined using zebrafish (Danio rerio) as a model, focusing on survival and embryonic development. Methodology: Zebrafish embryos, at approximately 3-hours post-fertilization (hpf), were exposed over 96 h to environmentally relevant concentrations of MDPV forms (0.18−2.8 μg L−1). Each treatment and control group included 50 animals distributed across 5 replicates. Mortality was assessed at multiple developmental stages (7, 24, 48, 72, and 96 h), along with cumulative mortality. Developmental endpoints included spontaneous movements (24 h), heartbeat (48 h), and hatching rate (48 and 72 h), quantified using stereomicroscopy and video analysis. Results: MDPV showed concentration and enantioselective effects, with (S)-MDPV being the most toxic. Behavioral and cardiac responses varied across forms, while hatching depended on concentration and time without a clear enantioselective pattern. Conclusions: MDPV disrupts early zebrafish development, impairing survival and embryonic development in a concentration-dependent and enantioselective manner, with (S)-MDPV demonstrating greater toxicity. These findings emphasize the importance of considering chirality in the environmental risk assessment of psychoactive contaminants such as SC, as enantiomer-specific effects may influence organism fitness, survival, and broader ecological outcomes.

Proceedings doi: 10.3390/proceedings2026146072

Authors: Ana Marcelino Catarina Caldeira-Santos Melanie Court Joana Raimundo Rui Rosa

Environmental contamination by rare earth elements (REEs) is increasing globally due to their extensive use in modern technologies, medicine, agriculture, and aquaculture. Their release into aquatic systems via wastewater discharge, industrial emissions, surface runoff, and atmospheric deposition has raised concerns regarding their environmental fate and potential ecotoxicological effects. Despite this, information on REE accumulation in marine predators remains limited. This study provides a multi-species assessment of REE bioaccumulation in elasmobranchs. Concentrations of 14 REEs (Ce, Dy, Er, Eu, Gd, Ho, La, Lu, Nd, Pr, Sm, Tb, Tm, and Yb) were quantified in liver and muscle tissues of six elasmobranch species collected from demersal and deep-sea habitats along the Portuguese continental shelf. Generalized linear models (GLMs) were used to evaluate differences in REE concentrations among species and tissues, and to explore potential patterns associated with ecological traits. Results indicated that REE concentrations varied significantly across tissues and species, with muscle generally exhibiting higher accumulation than liver. Overall, this study provides the first comprehensive baseline of REE bioaccumulation in elasmobranchs from the Portuguese coast, contributing to a better understanding of emerging contaminants in marine food webs. These findings have important implications for environmental biomonitoring and highlight potential risks associated with seafood consumption.

Proceedings doi: 10.3390/proceedings2026146068

Authors: Stefano Brignone Bernardo Quintella Rui Rivaes Ana Filipa Silva Pietro Volta Filipe Ribeiro

Introduction: Understanding the movement ecology of invasive species such as the European catfish Silurus glanis, with documented strong impacts on freshwater fish communities, is essential to improve the effectiveness of management and containment actions, as detailed knowledge of species spatio-temporal habitat use strongly influences the success of control strategies. Objective: This study aimed to investigate the spatial and temporal behaviour of the S. glanis in a river–reservoir system in Portugal, including the Ponsul River and part of the Tagus River within the Cedillo reservoir, and to provide ecologically relevant insights to support targeted management strategies. Methodology: Acoustic telemetry was used to monitor 27 tagged individuals equipped with depth sensors. Fish movements were tracked using an array of 17 acoustic receivers over one and a half years. Results: Three behavioural profiles were identified: a resident group in the lower Ponsul (n = 4), a group moving between the Tagus River and the lower Ponsul (n = 6), and a larger group primarily migrating within the Ponsul River (n = 12). The remaining five individuals were considered dead, due to illegal fishing in this protected area. Migratory individuals showed a clear seasonal pattern, moving downstream to deeper waters during early winter and returning upstream to shallower areas as temperatures increased in early spring, likely in response to thermal gradients. Distance-based analyses confirmed this trend, with minimum inter-individual distances occurring in winter and early summer. Vertical behaviour supported this pattern, with individuals occupying shallow waters (≤7 m) for most of the year and reaching depths of up to 30 m in winter. Conclusions: The observed preference for shallow habitats during warmer periods and downstream migration in winter indicates that eradication efforts should be spatially and temporally targeted. Control actions should prioritize upstream sections during warm seasons and downstream areas of the Ponsul during winter migration, focusing efforts on traditional methods such as large-mesh multimesh gillnets or new longline techniques. Overall, this study highlights the value of telemetry in supporting targeted, evidence-based management of invasive species.

Proceedings doi: 10.3390/proceedings2026146065

Authors: Margarida Vilaça Rosária Seabra Maria João Rocha Eduardo Rocha Célia Lopes

Introduction: The temperature of rivers in the Iberian Peninsula has increased due to global warming. In addition, these rivers are polluted by contaminants of emerging concern, such as polycyclic aromatic hydrocarbons (PAHs). Higher temperatures and pollution concurrently impose threats to the Iberian Peninsula’s endemic species, including the brown trout (Salmo trutta), a cold-water species widely used in ecotoxicological studies. Because the liver is the main biotransformation organ, and is particularly sensitive to both chemical and temperature changes, in vitro liver models may represent valuable alternatives for assessing combined stressor effects, complying with the 3Rs principle. Objective: In line with the above, the present study aimed to evaluate the combined effects of a 4 °C temperature increase and the model PAH benzo[k]fluoranthene (B[k]F) on fish liver cells using a primary brown trout hepatocyte culture as a model. Methodology: Primary hepatocytes were seeded in 6-well plates at a density of 1.0 × 106 cells/mL and exposed for 48 h to 1, 10, and 20 µM B[k]F at 18 °C (normothermia) and 22 °C (warming scenario). Cell viability was assessed using trypan blue, alamarBlue, and lactate dehydrogenase (LDH) assays. Cytochrome P450 (CYP)1A was evaluated in terms of its gene expression by RT-qPCR and its protein expression through immunocytochemistry (ICC). The immunostaining was quantified using a score system which considered five intensity staining levels. Results: Exposure to B[k]F and to the higher temperature increased LDH leakage without interaction effects. In contrast, the other viability assays did not show significant differences across conditions. Regarding CYP1A, both gene and protein expression increased with all B[k]F concentrations in relation to the controls, but were not influenced by temperature. Notably, the lowest B[k]F concentration (1 µM) elicited the highest CYP1A gene expression, suggesting a non-monotonic response. Conclusions: Overall, the model was responsive to both temperature (4 °C) increase and to B[k]F, validating its usefulness for assessing liver pollutant effects in the context of global warming. These findings support the application of fish primary hepatocyte models as relevant tools in ecotoxicology under environmentally realistic multi-stressor scenarios.

Proceedings doi: 10.3390/proceedings2026146062

Authors: Sabrina M. Rodrigues Francisco Lopes Cristina Marisa R. Almeida Sandra Ramos

Introduction: The early stages of fish represent a critical phase for survival and recruitment, as they are highly vulnerable to both biotic and abiotic factors, as well as anthropogenic pressures. To enhance survival, many marine species use estuaries as nursery areas. However, these ecosystems are increasingly exposed to contaminants such as microplastics (MPs; plastic particles < 5 mm) that can cause several direct or indirect negative impacts on fish larvae, namely impairing their development or survival. Objective: This study aimed to quantify and compare temporal changes in the ratio of microplastics (MPs) to fish larvae (FL) (MP:FL) in the Douro estuary (NW Portugal), assessing how exposure to MPs varies across years and seasons. Methodology: Seasonal sampling campaigns were conducted in the Douro estuary during 2021/2022 and 2025. Multiple stations along the estuary were sampled using plankton tows with a 0.5 mm mesh size. In the laboratory, fish larvae were sorted and identified, and the remaining material was processed to isolate and quantify MPs. The recovered MPs were subsequently characterized according to type, size, and color. Results: Data from 2022 indicated that Clupeidae, Gobiidae, and Gadidae were the most abundant fish families, while colorless and blue fibers between 2 and 3 mm were the dominant MP types. Data from 2025 showed that Gobiidae, Labridae, and Atherinidae were the most abundant families, with similar MP types observed in water in 2022. The ratio of MPs:FL in summer and autumn of 2021/2022 was 36 and 65 MPs:1 FL, respectively, whereas in 2025 it was 0.26 and 3.80 MPs:1 FL, respectively. Conclusions: These preliminary results indicate a decreasing trend in the ratio of MP:fish larvae over time. Although further data analysis is ongoing, the observed interannual differences highlight the importance of long-term monitoring of estuarine nursery areas to better understand contamination dynamics and their potential effects on early fish life stages.

Proceedings doi: 10.3390/proceedings2026146069

Authors: Sabrina M. Rodrigues Francisca Espincho Michael Elliott Cristina Marisa R. Almeida Sandra Ramos

Introduction: The physical characteristics of microplastics (MPs), particularly their size and color, closely resemble natural food prey for several marine organisms, leading to active or accidental ingestion by marine species, including fish larvae. Despite growing concern, the occurrence of MPs in wild fish during early developmental stages remains insufficiently documented, and laboratory studies report inconsistent results. Given their key ecological role in marine food webs and their economic relevance, the health and survival of fish larvae are critical for maintaining fish populations. Objective: This study aimed to investigate MPs’ presence throughout the larval developmental stages and assess whether MP contamination profiles (concentration, color, type, and size) differ between species. Methodology: MPs were analyzed in the larval stages of two fish species with distinct ecological niches: the European sardine (Sardina pilchardus), a marine migratory species, and the common goby (Pomatoschistus microps), an estuarine resident species. Samples were collected from the Douro Estuary (NW Portugal) over one year, covering different developmental stages. Results: MPs were detected in both species at all developmental stages observed, including the yolk-sac stage (where the feeding of larvae is endogenous), indicating contamination at a stage when the mouth is not yet functional. Sardina pilchardus showed a higher abundance of transparent nylon fibers of 0.5 mm, and Pomatoschistus microps transparent polypropylene fibers of size 0.4 mm. Moreover, MP contamination did not vary between species or throughout the developmental stages, showing similar levels and profiles of MPs contamination. Conclusions: These findings provide new evidence that MP contamination begins at the earliest developmental stages of the fish, from hatching onwards. The results further suggest that MP uptake in fish larvae is primarily driven by environmental availability rather than fish larvae’s preferences or ecological guild, physical characteristics, or even the ontogenetic developmental stage.

Proceedings doi: 10.3390/proceedings2026146070

Authors: Francisco José Oliva-Paterna Antonio Zamora-López Adrián Guerrero-Gómez Víctor Manuel Alvaréz-Navarro Antonio Andrés Herrero-Reyes Elena Parra-Espín José Manuel Zamora-Marín Mar Torralva

Introduction: Long-term ecological monitoring is essential to understand the responses of fish communities to global change in transitional ecosystems. Coastal lagoons are particularly vulnerable to eutrophication, which can trigger abrupt regime shifts, mass mortality events, and loss of ecological functions. The Mar Menor coastal lagoon (SE Spain) represents one of the most impacted Mediterranean systems, providing a unique opportunity to assess long-term ecological responses of fish assemblages to sustained anthropogenic pressure. Objetives: This study aims to synthesize long-term monitoring data to evaluate structural, functional, and population-level responses of fish assemblages to eutrophication processes, and to identify critical habitats and mechanisms supporting resilience. Methodology: We integrated multiple datasets derived from long-term monitoring programs (2002–2004 as and 2018–2025), including community structure, functional diversity, population dynamics of resident species, and habitat-based indicators. Analyses encompassed pre-impact, eutrophication, and post-disturbance phases, allowing for a multi-scale assessment of ecological responses. Results: Eutrophication-driven disturbances caused major shifts in fish assemblages, including declines in biomass and abundance, species-specific responses, and increased dominance of opportunistic trophic groups. Functional diversity analyses revealed strong homogenization processes and loss of specialist traits, indicating reduced ecosystem functionality. Population dynamics of resident species reflected habitat degradation, highlighting their value as ecological indicators. Despite these impacts, shallow coastal habitats acted as critical refuges, buffering hypoxic conditions and enabling partial persistence and recovery of fish communities. Conclusions: Our results demonstrate that long-term monitoring provides essential insights into the mechanisms driving fish community responses to eutrophication. The identification of functional changes and refuge habitats is key for adaptive management. Protecting and restoring critical habitats, particularly shallow areas, is crucial to enhance resilience and guide conservation strategies in Mediterranean coastal lagoons under global change.

Proceedings doi: 10.3390/proceedings2026146066

Authors: Sofia Esquível Rodrigo Alves Eduardo Rocha Tânia Vieira Madureira

Introduction: Glucagon-like peptide-1 receptor agonists (GLP-1 RAs), such as liraglutide (LIR), are widely used in humans to treat type 2 diabetes mellitus, obesity, and non-alcoholic fatty liver disease. In mammals, GLP-1 RAs have been shown to influence hepatic lipid metabolism, although the underlying mechanisms remain unclear. In fish, GLP-1 also plays an important role in regulating hepatic processes, including glycogenolysis, gluconeogenesis, and lipolysis. However, the effects of GLP-1 RAs on liver lipid metabolism in fish remain largely unexplored. Objective: This study aimed to evaluate the effects of LIR on lipid target genes using primary hepatocytes from brown trout as an in vitro model. Methodology: After 24 h, a hepatocyte monolayer culture was established, and cells were exposed for 24 and 48 h to supplemented L-15 medium (control), 0.1% dimethyl sulfoxide in supplemented L-15 medium (solvent control), and five single exposures to LIR at 1, 10, 100, 500, and 1000 nM. After 24 and 48 h, cell viability was assessed using the trypan blue exclusion assay. Gene expression was analysed by real-time qPCR, targeting genes involved in lipogenesis, lipid transport, and cholesterol efflux. Results: No concentration-dependent effects on cell viability were observed. Gene expression analysis showed that LIR exposure modulated the mRNA levels of lipid-related genes, including acetyl-CoA carboxylase (ACC), acyl-CoA long-chain synthetase 1 (Acsl1), and fatty acid synthase (FAS), with time being the main influencing factor. Overall, expression levels were higher at 48 h compared to 24 h. Additionally, dose-dependent effects were observed for ACC expression, with higher LIR concentrations showing significant differences compared to controls. Conclusions: These findings indicate that LIR modulates lipid-related gene expression in primary hepatocytes of brown trout without affecting cell viability. The results suggest that GLP-1 receptor activation may influence key pathways involved in hepatic lipid metabolism, with time-dependent effects playing a predominant role. Overall, this study supports the use of brown trout primary hepatocytes as a suitable in vitro model for investigating hepatic lipid responses to LIR and other GLP-1 receptor agonists, while providing initial insight into their potential effects in fish.

Proceedings doi: 10.3390/proceedings2026146059

Authors: Paloma Moreno-Rendón César Esteban Simón-Talero Guadalupe de la Cruz Ortiz César Fallola Sánchez-Herrera Miguel Angel Cotallo de Cáceres

European catfish, an invasive alien species (IAS) that inhabits the Tagus River in Extremadura, is a threat to freshwater biodiversity and the local economy. As a freshwater mega-predator, it eats all kinds of fish, impacting local ichthyofauna as well as sport-recreational angling, a major economic driver in Extremadura, with 100,000 angling licenses issued by the Extremadura local government and more than 1000 annual bank fishing competitions. The introduction of Silurus glanis into Tagus basin is recent, dating to the 20th century, but it has rapidly spread. Although this expansion is driven by anglers, boat anglers account for only two per thousand anglers in the region, and even among them European catfish anglers are scarce, as fishing for this species is prohibited in the region and local anglers and anglers associations are against European catfish expansion. Efforts to control catfish in Extremadura have been based on studies of selective capture methods, such as trammel nets, gill nets, long lines, fish traps, and electrofishing combined with nets in areas where barbel congregate during their spawning migration. The most effective and selective methods for European catfish, avoiding bycatch, are trammel nets and electrofishing. Therefore, a combination of these methods and collaboration between local government and anglers are proposed for its control in reservoirs. In cases of recent introductions into standing water, rapid actions have been taken, involving complete drainage of the water body, rescue of native fish and removal of European catfish. These measures are feasible in reservoirs up to 10 hectares and can be combined with sediment management to improve water quality. Deterrence and control measures have been implemented in response to the promotion of catfish angling in regional media and on social media. To control European catfish expansion, collaborative actions involving public agencies, local government, angler associations and public awareness are essential.

Proceedings doi: 10.3390/proceedings2026146060

Authors: Tiago Lourenço Maria João Rocha Eduardo Rocha Tânia Vieira Madureira

Introduction: Fish and humans share evolutionarily conserved pathways regulating lipid metabolism. However, the effects of pharmaceuticals on lipid homeostasis in fish remain poorly understood, particularly regarding mechanistic lipid dysregulation and its implications for fish physiology and environmental toxicology. While hypolipidemic drugs such as statins have been shown to modulate lipid metabolism in teleosts, other lipid-lowering agents, including cholesterol absorption inhibitors, remain largely unexplored. Additionally, synthetic hormones have been shown to interfere with lipid regulation, although their effects—particularly those of progestins—remain poorly characterized. Objective: This study aimed to explore the mechanistic lipid disruptions induced by potential hypo- and hyperlipidemic modulating pharmaceuticals in brown trout juveniles exposed to subchronic pharmacological conditions. Methodology: Juvenile brown trout were exposed via intramuscular injection every 72 h for 28 days and allocated into six experimental groups (n = 12 per group): control (C; 0.7% NaCl), solvent control (SC; 0.7% NaCl, 0.9% ethanol, 0.1% dimethyl sulfoxide), atorvastatin (ATV; 0.3 µg·g−1), ezetimibe (EZB; 0.3 µg·g−1), 17α-ethinylestradiol (EE2; 2 µg·g−1), and levonorgestrel (LNG; 0.1 µg·g−1). All concentrations represented pharmacological doses. On day 28, the fish were euthanized and sampled. Endpoints included biometric measurements, blood lipid profiling, serum biochemistry, and hepatic lipid accumulation. Results: ATV fish displayed greater body length, whereas EE2 increased liver weight and hepatosomatic index. EE2 reduced high-density lipoproteins and increased low-density lipoproteins, while atorvastatin reduced low-density lipoproteins. EE2 exposure also increased albumin levels and decreased glucose concentrations. Furthermore, EE2 significantly enhanced hepatic lipid deposition. Conclusions: The hyperlipidemic effects of EE2 were the most pronounced, whereas ATV produced the strongest hypolipidemic responses, consistent with its known effects in humans, and also influenced biometry. These findings provide a robust foundation for understanding how pharmaceuticals influence lipid metabolism and related physiological processes such as growth in fish, with relevance for both fish physiology research and environmental toxicology.

Proceedings doi: 10.3390/proceedings2026146057

Authors: Ondina Ribeiro Luís Félix Antonio De la Vieja Monica Torres-Ruiz João Soares Carrola

Introduction: Chemical pollution of water bodies constitutes a global problem with huge impacts on fish populations. Consequently, the assessment of the effects of contaminants, especially on the nervous system, has become essential. The zebrafish (Danio rerio) has emerged as a prominent vertebrate model in ecotoxicology and neuroscience, in large part owing to the availability of genetic resources, including a high level of genome sequencing and annotation, plus the similarity of its neuron types and neurotransmitters to other vertebrates, including humans, and its stereotyped behaviour. Objective: The main objective of this mini-review is to present a synthesis of the key behavioural assays used in zebrafish larvae to assess neurotoxicity, focusing on developmental neurotoxicity. Methodology: A literature review was conducted based on the ScienceDirect and PubMed databases, covering publications between 2000 and 2025, selecting relevant studies on larval (up to 120 hpf) behaviour and contaminant exposure. The methodology was based on the analysis of behavioural tests applied to larvae, which evaluate responses to various stimuli, including visual, acoustic, tactile, and social stimuli. Results: Established, commonly used key assays include the light/dark test and locomotor, touch, photomotor, acoustic, and social response tests. The literature results confirm that zebrafish larvae exhibit complex behavioural patterns comparable to those of higher vertebrates, making them suitable for neurobehavioural studies. Changes in locomotor behaviour, responses to stimuli, or social patterns are extremely sensitive indicators of early neurotoxic effects, often before morphological changes are observed. Furthermore, the developing nervous system is particularly sensitive to chemicals, with high potential for irreversible effects, even with short-term exposures. Conclusions: Overall, our findings demonstrate that behavioural assays in zebrafish larvae constitute an effective, sensitive, and economically viable tool for assessing the neurotoxicity of compounds, contributing to a better understanding of the mechanisms of action and advancing environmental protection and public health strategies, considering also the “one health” approach.

Proceedings doi: 10.3390/proceedings2026146061

Authors: Francisco Baldó Miguel Ángel Cortes-Pujol David Barros-García Juan Manuel Martínez-Vázquez Rafael Bañón

Introduction: Elasmobranchs are an important component of deep-water and slope ecosystems, playing a key role in benthic and demersal food webs. Many species inhabiting offshore banks of the northeastern Atlantic are characterized by low productivity and high sensitivity to fishing pressure, which makes fishery-independent assessments particularly relevant. The Porcupine Bank supports a diverse assemblage of deep-water sharks and skates, yet quantitative information derived from standardized trawl surveys remains essential to characterize community structure and support ecosystem-based management. This study aims to provide an updated overview of the composition, relative abundance, biomass, and occurrence of elasmobranch species on the Porcupine Bank. Methodology: Data were collected during the Porcupine bottom trawl survey carried out in September–October 2023. The survey used a stratified random sampling design by depth and comprised a total of 88 valid demersal trawl hauls. Results: A total of 23 elasmobranch species belonging to four orders (Carcharhiniformes, Squaliformes, Rajiformes, and Hexanchiformes) were recorded. The assemblage was dominated by deep-water sharks, particularly squaliforms and carcharhiniforms. Galeus melastomus was the most dominant species, showing the highest stratified mean biomass and abundance and occurring in the majority of hauls. Other abundant and recurrent species included Etmopterus spinax, Scyliorhinus canicula, and Deania calceus. Skates of the genera Dipturus and Leucoraja were less abundant but showed consistent occurrences across depth strata. Several deep-water species, such as Apristurus spp. and Rajella fyllae, were recorded only sporadically, with very low abundances and limited occurrence. Conclusions: The results highlight the predominance of small- to medium-sized deep-water sharks on the Porcupine Bank and the comparatively lower contribution of rajid skates. This study provides a robust description of elasmobranch assemblage structure based on standardized sampling and constitutes a valuable baseline for future monitoring and comparative assessments in offshore Atlantic ecosystems.

Proceedings doi: 10.3390/proceedings2026146056

Authors: António Tovar Faro João Manuel Oliveira Pedro Segurado Verónica Pinto Lia Barros Felisbina Quadrado Tamara Leite Gonçalo Duarte Paulo Branco Teresa Ferreira

Introduction: Despite more than two decades of implementation, the European Water Framework Directive (WFD) still faces major challenges in achieving good ecological status across European water bodies. Key limitations persist in connectivity restoration, transboundary harmonization, monitoring network design, and biological assessment of complex systems such as large rivers, reducing the Directive’s capacity to provide consistent ecological diagnoses and support effective river basin management. Objective: This work had four objectives: (I) incorporate ecological status into connectivity assessments; (II) evaluate harmonization in Iberian transboundary basins; (III) optimize the national fish monitoring network through co-creation; (IV) develop a fish-based multimetric index for Portuguese large rivers. Methodology: The work combined four approaches: (1) graph-based connectivity analysis integrating the probability of achieving good ecological status to evaluate functional connectivity across European river networks; (2) cross-border comparison of ecological classifications between Portugal and Spain in shared Iberian basins; (3) optimization of the Portuguese fish monitoring network through a co-creation approach involving the national authority; (4) development of a fish-based multimetric index designed for Portuguese large rivers. Results: Integrating ecological status into connectivity analyses reduced estimated connectivity and highlighted the combined effects of fragmentation and degradation. Cross-border comparisons showed that formal harmonization does not ensure consistent ecological classification. The optimized monitoring networks improved ecological representativeness without increasing sampling effort, while co-creation ensured operational feasibility. The new fish index for large rivers captures spatial variation in ecological quality and responds to pressure gradients, addressing a recognized methodological gap. Conclusions: Improving WFD implementation requires progress across multiple complementary components rather than isolated advances. More effective river management depends on integrating ecological processes, comparable assessment outputs, representative monitoring networks, and system-specific tools. These approaches provide transferable pathways for strengthening freshwater assessment and supporting more coherent river restoration and management across Europe.

Proceedings doi: 10.3390/proceedings2026142010

Authors: Shah Asim Azhar Malik Shafaq Mahmood Ayesha Iftikhar

Universities increasingly rely on digital self-service channels to manage high volumes of time-sensitive admissions enquiries. AI enabled chatbots represent a prominent solution because they can provide round-the-clock responses, standardize guidance, and potentially reduce uncertainty for applicants. Yet evidence on whether such chatbots meaningfully assist students and improve their satisfaction with admissions support remains limited in many developing higher education contexts. This quantitative study evaluates the perceived effectiveness of AI chatbots used for university admissions in Pakistan, with a focus on student assistance and satisfaction as key outcomes. Using a cross-sectional survey design, data were collected from students who had recently engaged with university admissions information services (e.g., website chat widgets, messaging-based virtual assistants, and admissions enquiry portals) across private universities in Pakistan. Admissions chatbot effectiveness was measured through established information systems and service quality constructs system quality (ease of use, responsiveness, accessibility), information quality (accuracy, clarity, completeness), and service quality and trust cues (assurance, privacy confidence, and appropriateness of conversational support). Student assistance captured the extent to which chatbot interactions helped participants complete admissions related tasks and navigate application procedures. Student satisfaction reflected overall evaluation of the admissions support experience. The results indicate a positive association between perceived chatbot quality and perceived student assistance, and a further positive association between student assistance and student satisfaction with admissions support. The overall pattern suggests that student assistance functions as a key mechanism through which chatbot effectiveness translates into satisfaction. At the same time, respondents highlighted limitations in resolving complex or exception based queries, emphasizing the importance of transparent escalation to human admissions staff. The study contributes context specific evidence from Pakistan and offers an empirically grounded framework that university administrators can use to evaluate and improve admissions chatbots. Practical implications emphasize maintaining accurate knowledge bases, designing clear handoff pathways, and implementing governance practices that strengthen students’ confidence in information reliability and data privacy.

Proceedings doi: 10.3390/proceedings2026146058

Authors: Diogo Ribeiro Christos Gkenas Diogo Dias Mafalda Moncada Beatriz Castro Rui Rivaes Filipe Ribeiro

Introduction: The colossal European catfish (Silurus glanis) is the largest invasive freshwater fish on the Iberian Peninsula, reaching up to 2.8 metres and 130 kg in weight. Its large size makes it a highly valued target for recreational anglers, leading to repeated illegal introductions across several Iberian watersheds. Despite its appeal to anglers, this species is recognised as a high-impact invasive predator with substantial ecological consequences for European freshwater ecosystems. Recently, large catfish aggregations have been reported by anglers and environmentalists in several areas of Portugal and Spain. These impressive aggregations are frequently documented on videos and posted on social media networks (Facebook, WhatsApp groups, etc) or shared directly with our team members. Objective: Such records provide a valuable source of information for identifying the habitats and seasonal periods associated with aggregation behaviours and may therefore support more efficient management and population control actions. Methodology: We compiled information on European catfish aggregation events in Southern Iberia, namely date and location. The catfish aggregations were mapped, and their general habitat characteristics were described. Results: We recorded 10 catfish aggregation events, most of which occurred between May and June. These were generally located in transitional areas between lentic and lotic habitats, especially in narrower river sections. Possible explanations include hydromorphological constraints, seasonal environmental conditions, and species-specific behavioural responses, although these mechanisms require further investigation. Conclusions: Within the LIFE PREDATOR project, which focuses on the management of European catfish in the Tagus watershed, knowledge of aggregation locations is important to direct population control efforts aimed at reducing the abundance of this invasive fish. Moreover, the identification of common habitat characteristics may help predict other potential aggregation sites and improve the planning of future management actions.

Proceedings doi: 10.3390/proceedings2026146055

Authors: João Oliveira Miguel Macário Vanda Andrade Paula Ruivo Maria Oliveira João Gago Filipe Ribeiro Abigail Lynch

Introduction: Inland fisheries in their diverse forms are an important activity in Portugal, currently involving about 100,000 fishers. Despite their relevance, there is still limited knowledge regarding the economic multiplier effect associated with this activity, including its contribution to local and regional economies, its broader socio-economic impacts, and its role in promoting nature-based tourism. Objective: The INFISHERIES.PT project aims to characterize the socio-economic value of inland fisheries in Portugal. Methodology: The three main fishing activities in Portugal (professional, sport, and recreational fisheries) were considered to assess inland fisheries’ economic value. Data on annual expenditures of competitive sport anglers were collected through an online questionnaire distributed by the Portuguese Federation of Sport Fishing, while data on recreational fishers were obtained through face-to-face surveys. The analysis of professional fisheries was based on official catch declarations submitted to the national licensing authority (ICNF) between 2012 and 2024. Interim Results: Results for sport fisheries indicate an estimated mean annual direct expenditure of €6.7 million, with fishing equipment accounting for the largest share, followed by travel, meals, and accommodation. Social interaction was identified as the main motivation for recreational fishing, followed by contact with nature, as well as motivations related to peace, relaxation, and entertainment. Respondents most frequently reported annual expenditures between €100 and €499 on fishing equipment, travel, and food during fishing trips. Regarding professional fisheries, results highlight the increasing importance of non-native species in total catches, particularly the red swamp crayfish, in recent years. Native migratory species, such as the European eel, sea lamprey, and allis shad, despite lower catch volumes, maintain high market value and make a significant contribution to total revenue. Conclusions: The results obtained to date in this project indicate that freshwater fishing in Portugal is a relevant activity, both in its commercial and non-commercial forms, and plays an important economic role at local and regional levels. Moreover, sport and recreational angling, in particular, also serve as drivers of nature-based tourism, potentially contributing to increased environmental awareness among the population and pressuring authorities to maintain freshwater ecosystems in good ecological condition.

Proceedings doi: 10.3390/proceedings2026146054

Authors: Roberto Rocha Tavares Rafael Gaio Kulzer Rodolfo Miguel Silva Régis Vinícius Souza Santos Alberto Teodorico Correia

Introduction: Understanding population structure is essential for fisheries management and stock identification. In marine species, spatial differentiation may arise from environmental conditions and biological factors, even when populations appear continuous. Otolith shape and body analyses have been widely used as effective tools to detect such differences, as they reflect both genetic and environmental influences. Objectives: The main objective of this study was to assess the population structure of Sarpa salpa in three fishing grounds in the Northeast Atlantic using two geometric morphometric approaches. Methodology: A total of 133 individuals collected between November 2025 and March 2026 from Santa Maria (n = 48), Peniche (n = 36), and Olhão (n = 49) were analyzed using two geometric morphometric approaches. The first involved otolith contour analysis using Elliptical Fourier Descriptors (EFD), with 12 descriptors explaining 90% of the cumulative variance. The second approach used truss network analysis based on 11 body landmarks, corresponding to 22 transformed distances (TD). Statistical analyses included multivariate analysis of variance (MANOVA), Hotelling’s T-square tests (HT2) for multiple comparisons, and linear discriminant function analysis (LDFA), with reclassification success assessed using a jackknifed (leave-one-out) classification matrix (JKM). Results: EFD analysis showed significant differences for MANOVA, with significant HT2 between all locations, but LDFA indicated considerable overlap, with a global JKM reclassification rate of 60%. In contrast, TD also showed significant MANOVA results, with significant HT2 across all comparisons. However, LDFA demonstrated clear separation among the three groups, achieving a JKM overall reclassification success of 98%. Conclusions: The results indicate that geometric morphometrics based on body landmarks provides greater discriminatory power than otolith contour analysis for identifying population structure. These results suggest the existence of distinct population units of Sarpa salpa in the Northeast Atlantic, highlighting the importance of spatially explicit approaches for fisheries assessment and management.

Proceedings doi: 10.3390/proceedings2026146052

Authors: Xavi Giménez-Borrás Carolina Ayelén Ángela Brotons Pilar Risueño Victor Gallego

Introduction: The fartet (Apricaphanius iberus) and the samaruc (Valencia hispanica) are two endemic fish species from the Valencian Community that have experienced significant population declines due to habitat degradation, competition with invasive species, and the impacts of climate change. Despite their critical conservation status, key aspects of their population dynamics and reproductive biology remain poorly understood. Objective: This study aimed to assess the resilience of their embryos to water stress through diapause-like mechanisms. Methodology: For studying the embryonic arrestment, eggs were collected from captive populations and subjected to different incubation periods (1, 3, 7, 10 and 14 days) on different substrates (commercial sand and filter paper). Hatching rates were analyzed in relation to the duration of exposure to stress water conditions and the type of substrate used. Results: The experiments conducted demonstrated that the embryos of both species were able to withstand water stress conditions (eggs out of the water). In the case of the samaruc, the results showed that eggs collected in both May and June could resist water-stress conditions for at least 10 days, exhibiting hatching rates of 100% during this period, which decreased to 50% by day 14. Regarding the fartet, embryos from eggs collected in May were able to survive up to 3 days under water-stress conditions, with hatching rates of 100%. In contrast, embryos from eggs collected in June showed greater resilience to water stress, with high hatching rates of 60–100% at days 7 and 10. Conclusions: These results suggest that, although a mechanism like embryonic diapause may be present in these species, its effectiveness as an adaptive strategy may depend on multiple environmental factors not controlled in this study, such as temperature, oxygen availability, and water salinity. The absence of hatching after prolonged incubation periods indicates that, if a diapause mechanism exists in these species, it may not be as efficient as in other annual cyprinodontiforms adapted to extremely fluctuating environments. These results highlight the importance of adaptive management measures to mitigate the effects of climate change and ensure the long-term persistence of both species.

Proceedings doi: 10.3390/proceedings2026146051

Authors: João Gago Miguel Macário Vanda Andrade Paula Ruivo Maria Oliveira João Oliveira Filipe Ribeiro Abigail Lynch

Introduction: Competitive sport angling is a specialized form of recreational fishing in which participants compete in tournaments throughout the year to obtain annual rankings. In Portugal, competitive anglers may exhibit high levels of engagement and expenditure, yet the economic relevance of this activity remains poorly documented. Objective: This study aimed to assess the economic value of inland competitive angling competitions in Portugal. Methodology: Data on anglers’ annual expenditures were collected through a web-based questionnaire distributed in April 2025 by the Portuguese Federation of Sport Angling to 1,230 registered federated anglers. A total of 193 valid responses were obtained, including information on socio-demographic characteristics, angling modalities, and fishing locations, as well as expenditures on fishing equipment, travel, meals, accommodation, and willingness to pay (WTP) to ensure fish availability during competitions. Results: Extrapolation of the results to the national federated inland angler population suggests an estimated annual direct expenditure of approximately €6.7 million, ranging from €4.2 million to €9.2 million. Fishing equipment (e.g., rods, reels, boats, kayaks, and paniers) accounted for the largest share of expenditures, followed by travel, meals, and accommodation. Expenditure patterns varied according to age, angling modality, years of competitive experience, and participation in both inland and marine competitions. Most respondents (62.7%) reported being unwilling to pay additional amounts to guarantee fish availability, arguing that this responsibility should fall on the state and competition organizers given the fees already paid. Conclusions: Inland competitive sport angling appears to make a relevant contribution to economic activity associated with tourism and leisure services in Portugal and should therefore be considered in the management of inland water resources.

Proceedings doi: 10.3390/proceedings2026146043

Authors: Cláudia A. Rocha Tânia Martins Patrícia Carneiro Luís M. Félix Sandra M. Monteiro Carlos Venâncio

Introduction: Aquatic ecosystems are major reservoirs for both legacy and emerging contaminants, facilitating their distribution throughout the environment and bioaccumulation across different trophic levels. As such, wildlife acts as a valuable tool for biomonitoring these contaminants and serves as a key indicator of environmental pollution within the One Health framework. Despite this, knowledge regarding the application of this framework alongside the assessment of aquatic contaminants using wildlife species remains fragmented. Objective: This study aims to synthesize current evidence on aquatic contaminants using wildlife as sentinels of environmental pollution and to explore how the One Health concept is applied in this field. Methodology: A systematic database search was conducted in SCOPUS, and the retrieved studies were screened according to predefined inclusion and exclusion criteria, as well as their relevance to the One Health concept. Results: Despite its timely relevance, only fourteen studies have adopted the One Health approach to assess contaminants in aquatic species. The selected studies focused mainly on plastic particles (53.33%), such as macro- and microplastics; heavy metals (26.67%), such as mercury (Hg), cadmium (Cd), Nickel (Ni), lead (Pb), and selenium (Se); persistent organic pollutants (13.33%), such as polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), per- and polyfluoroalkyl substances (PFAS), and dioxin/furans; and metalloid (6.67%) arsenic (As). These contaminants were evaluated across four different taxonomic groups: fishes (61.54%), waterbirds (23.08%), mollusks (7.69%) and crustaceans (7.69%). Most studies were conducted in Portugal (37.5%) and the United States of America (18.75%), whereas other countries, including Canada, Australia, Ecuador, Mexico, Indonesia, and Turkey, were mentioned in only one study each (6.25%). Conclusions: Monitoring levels of contaminants in wildlife is essential not only to understand the dynamics of environmental pollution, but also to preserve the integrity of ecosystems while safeguarding animal and human health. However, the limited number of studies adopting a One Health perspective results in an incomplete representation of contaminant classes and affected taxa. These findings highlight the urgent need to expand wildlife-based monitoring strategies within a One Health framework, aiming to improve environmental risk assessment and deepen our understanding of the impacts of pollution across ecosystems, animals and humans.

Proceedings doi: 10.3390/proceedings2026146032

Authors: Ricardo Estevens Telma Luís Samuel Ramos Pereira Vera M. Mendes Bruno Manadas Carolina Madeira Pedro M. Costa

Fish venom biology reaches far beyond addressing risks of human envenomation. The critical understanding of venom composition and the drivers that modulate it will enable scientists to deliver a span of novel bioresources with multiple potential biotechnological applications. The lesser weever fish (Echiichtys vipera), common in the surf of sandy beaches in Portugal, is a noteworthy case study due to frequent envenomation episodes during summer, albeit the lack of information regarding its venom system and the composition of its venom. We collected about one hundred animals from Costa da Caparica (W Portugal) as beach trawl (arte xávega) by-catch. Histology showed a similar essential microanatomical structure of glands in both venomous spines (dorsal and opercular) and no obvious gender differences. Transversal sections across the spines showed a T-shaped supportive bone structure that harbor masses of large, glandular cells that bear large sacculi. The structure is surrounded by a retractable layer of skin, thicker in the opercular spines comparatively to dorsal. The lack of muscular tissue near the glands and missing venom delivery ducts in the spines suggest that venom secretion in this species is holocrine, i.e., that venom is delivered through rupture of the skin and underlying glandular tissue upon mechanical pressure. Proteomics of the venomous spines (dorsal and opercular) showed a different proteomic signature between males and females, pointing to intersexual variation and suggesting that other biotic and abiotic factors might influence venom composition (maturation stage or geographic distribution). Additionally, protein homology matches performed against known toxins from marine venomous fishes indicated the presence of novel unexplored toxins in this species besides expected cytolysins. Our focus in the future is to identify, isolate and characterize the individual components of this venom. We anticipate new insights on the intraspecific adaptation of fish venom systems to specific ecological needs and advocate for sustainable bioprospecting for novel proteins with high biotechnological potential.

Proceedings doi: 10.3390/proceedings2026146041

Authors: Beatriz Castro Ivana Vejříková Filipe Ribeiro Diogo Dias Mafalda Moncada Diogo Ribeiro Rui Rivaes Jan Kubečka Mojmír Vašek Martin Čech Carlos Fernandez-Delgado Agustín P. Monteoliva Jaroslav Semerád Pietro Volta Lukáš Vejřík

Freshwater ecosystems in southern Europe are increasingly impacted by fish invasions from central and northern regions, often facilitated by warmer climates and reduced natural-enemy pressure. The European catfish (Silurus glanis), the largest freshwater fish in Europe, is now widely established across various southern European basins, where its high fecundity, ecological plasticity, and predatory behaviour pose significant risks to native communities. Despite its rapid spread, growth dynamics across native and non-native populations remains scatteredly described in studies with different approaches. Objective: This study compares growth rates between native populations in the Czech Republic and non-native populations in Portugal, Spain, and Italy, and assesses whether growth rates are influenced by introduction timelines, reflecting differences in population age and invasion stage. Methodology: Nine populations spanning the native range (central Europe) and non-native range (southern Europe) were analysed. A total of 427 different vertebrae were used to age the fish and growth was modelled using the von Bertalanffy growth function. Generalised linear models were used to identify environmental and demographic predictors of variation in the growth coefficient (K). Moreover, mark-recapture data from the native populatations was also analysed. Results: Preliminary results indicate substantial variation in growth among populations, with higher growth rates exhibited in non-native populations (Iberian), while native populations showed consistently lower growth rates. Growth was primarily associated with population age and minimum temperature, decreasing with increasing population age and increasing under warmer thermal conditions. These patterns suggest faster growth in recently established and warmer populations. Conclusions: Growth dynamics of European catfish vary markedly across native and non-native ranges, driven mainly by thermal conditions and invasion history. Faster growth in warmer and recently established populations may enhance invasion success by accelerating size-at-age and reproductive potential. This study highlights the importance of integrating environmental and demographic factors to improve predictions of invasion dynamics and ecological impacts in freshwater ecosystems.

Proceedings doi: 10.3390/proceedings2026145001

Authors: Ana M. Vernia-Carrasco

The Active Music Programme (MAP) is an interdisciplinary initiative designed to foster inclusion, communication, and emotional well-being through participatory music-making. Integrating active music education, guided improvisation, and creative interaction, MAP seeks to enhance quality of life for individuals with diverse abilities. This pilot project, implemented in a special education centre with adolescents and adults with Autism Spectrum Disorder (ASD), combines weekly collaborative sessions led by music and education professionals. Using a qualitative, participatory framework, the study aims to examine how musical engagement is expected to support shared attention, emotional regulation, and social connection, positioning MAP as a replicable model for inclusive education and community practice.

Proceedings doi: 10.3390/proceedings2026146036

Authors: Susana D. Amaral Ricardo Branca Ulisses Cabral João Pádua José M. Santos

Introduction: The Touvedo hydropower plant, located on the Lima River 47 km from its mouth, is equipped with a fish lift (2.14 m long × 1.29 m wide × 2.85 m high) on the left bank designed to facilitate fish migration past the dam. This mechanical system attracts fish by means of a guide current, traps them in a water-filled cage, and then lifts and releases them upstream, enabling passage over the dam. Within the framework of the Sustainability Policies from the EDP Group, particularly those related to Environment and Biodiversity, and under the Eel Management Plan, a long-term video-monitoring program has been implemented since 2011 to collect data on the species using the device and to evaluate its effectiveness. Objective: This study aims to present and analyze nine years of video-monitoring data collected across three programs—the “Action Plan for the Optimization of the Fish Lift at the Touvedo Hydroelectric Facility (2011/2014)”, which aimed to diagnose and assess the effectiveness of the fish lift and to define and implement measures needed to optimize its operation; “Video Monitoring of the Touvedo Fish Lift (2017/2020)”, that was carried out as a follow-up to the Action Plan; and more recently, a new video-monitoring project (2021–2024) which was implemented to expand the dataset and validate the patterns observed in the previous studies. Methodology: The fish lift was continuously monitored using an automatic video-recording system, which consists of a video camera installed at the top of the lift to capture images of the trapping cage during the final stage of its ascent, and a server for video storage. The trapping cage is lined with 20 cm × 20 cm white tiles to increase contrast and allow estimation of fish body length. Collected data included the timing of fish passage (day and hour), the number of fish per cycle, species-level identification and the estimated total length of each individual. Results: The European eel (Anguilla anguilla) has remained the dominant species using the lift, and, consistent with observations from Video-Monitoring 1, the Iberian barbel (Luciobarbus bocagei) has become the second most representative species, replacing the northern straight-mouth nase (Pseudochondrostoma duriense), whose proportion has declined. Brown trout (Salmo trutta) showed a slight but continued increase in Video-Monitoring 2, following the decrease recorded in Video-Monitoring 1 compared to the Action Plan. Conclusions: These results highlight the importance of continuing video monitoring of the Touvedo fish lift to assess its operability, confirm the observed passage patterns, determine the success of the implemented improvements, and evaluate the possible need for additional measures.

Proceedings doi: 10.3390/proceedings2026146038

Authors: Alejandra Cruz Raquel Merino-Aguirre Esther Lantero Belén Méndez-Cea Juan A. Ardura Josué García Yagüe Ana Clara Sampaio Franco Emili García-Berthou David H. Fletcher David Almeida

Habitat alteration and biological invasions are two main drivers of biodiversity loss at the global scale. Eutrophication and invasive fish greatly disturb freshwater native communities. This is of particular conservation concern in the Iberian Peninsula (Portugal and Spain), where fish fauna display a high level of endemism. For this eco-region, there is a dearth of information on the interactions among water quality, physical condition and parasites of invasive fishes. Consequently, the aim of this study was to assess the effect of nutrient enrichment on health status and parasitological traits in the invasive mosquitofish Gambusia holbrooki inhabiting an Iberian river. Water (n = 18 replicates, three per site) and fish (n = 400 individuals, 33–34 ind. per site and year) samples were collected in September 2024 and 2025 along the River Bullaque (central Spain). Sampling effort was standardised among sites, with the following parameters consistent: seine and pond nets were used, deployed by wading; 10:00 solar time; 1.5 h duration; personnel (the same seven trained researchers); and weather/environmental conditions; ensuring methodological consistency and data comparability. Laboratory procedures were carried out near the sampling sites to minimise both fish stress and distortions to parasite communities. Morphological and parasitological parameters were compared between mesotrophic and eutrophic reaches (six sampling sites, three per reach). Body condition and health assessment index* were greater under eutrophic conditions. Fluctuating asymmetry (a measure of developmental instability) was significantly higher for eye diameter in the mesotrophic reach. Parasite taxonomic composition differed between reaches, with more digeneans and cestodes in the mesotrophic sites, whereas ciliates and monogeneans were more abundant in mosquitofish from the eutrophic reach. Parasite prevalence, abundance and index of life-cycle complexity (heteroxenous species) were lower in the eutrophic reach. These results strongly suggest that eutrophication can facilitate mosquitofish invasiveness. This is reflected in a variety of morphological and parasitological traits, such as better body condition, health status, developmental stability, parasite resistance and tolerance. Overall, these parameters indicate that mosquitofish is taking advantage of anthropogenic impacts to improve their level of establishment and subsequent spread throughout Iberian fresh waters.

Proceedings doi: 10.3390/proceedings2026146046

Authors: Christos Gkenas Nicholas Koutsikos Katelyn Lawson Filipe Ribeiro Leonidas Vardakas

Introduction: Freshwater ecosystems are global biodiversity hotspots, yet they remain highly vulnerable to biological invasions. Non-native freshwater fish species (NNFS) have established self-sustaining populations across nearly all biogeographic realms, reshaping regional ichthyofaunas and driving community-level impacts through predation, competition, hybridisation and ecosystem disruption. Critically, both foreign introductions and within-country translocations (extralimital species) contribute to this process, yet the latter remain more weakly regulated and consistently under-studied in invasion risk frameworks. Objective: We developed a stage-structured profiling framework to jointly evaluate foreign and extralimital NNFS in Greece and predict three sequential invasion outcomes, establishment, spread and integration, with the goal of identifying the ecological traits and pathway variables that best explain invasion success at each stage and informing management policy. Methodology: We compiled a dataset of 63 NNFS recorded in Greek freshwaters (36 foreign, 27 extralimital), characterised by eleven ecological, biogeographic and anthropogenic attributes. Logistic and multiple regression models and classification and regression trees (CART) were fitted independently for each invasion stage, with cross-validated predictor screening to limit multicollinearity and a taxonomy-based covariate to account for phylogenetic non-independence. Results: All 27 extralimital translocations established successfully, compared with only 11 of 36 foreign introductions, underscoring the disproportionate establishment success of within-country movements. Establishment probability was positively associated with high physiological tolerance and proximity to the nearest native source, and negatively associated with maximum adult size; propagule pressure provided only weak additional support. Spread across drainage basins was driven primarily by introduction effort and physiological tolerance. Integration increased with introduction effort, while the CART identified distance from the nearest native source as the primary partition of widespread, high-abundance outcomes, with trophic level further structuring outcomes among extralimital taxa. Conclusions: Our results indicate that management frameworks focused solely on foreign NNFS substantially underestimate invasion risk from within-country translocations. A compact set of predictors, biogeographic proximity, physiological tolerance and introduction effort, offers a practical, pathway-inclusive screening tool to guide prevention, surveillance and early detection in Mediterranean river networks, addressing a recognised European policy gap where extralimital movements remain more weakly regulated than foreign introductions.

Proceedings doi: 10.3390/proceedings2026146053

Authors: Nuria Perez-Bielsa Lilith Weimer Helena Mas Sandra Heras Jose-Luis Garcia-Marin Alba Abras

Introduction: The Catalan chub (Squalius laietanus) is a freshwater cyprinid endemic to Catalonia, from the lower course of the Ebro River to the Tech, Tet, Agly, and Massane rivers in France. Classified as Vulnerable in the IUCN Red List (2024), its populations face significant threats due to anthropogenic pressures and the potential hybridization with the European chub (Squalius cephalus). Objective: This study aimed to characterize the genetic variation of the mitochondrial control region (CR) of S. laietanus across the main Catalan river basins to determine the population genetic structure of this species in the core of its distribution range. Methodology: A 789 bp fragment of the CR was sequenced in 334 chubs from 24 sampling sites collected by electrofishing between 2021 and 2025. The S. laietanus specific matrilineage of all these specimens had been previously detected by sequencing the Cytochrome c oxidase subunit I (COI) but this marker did not detect clear genetic structuring among basins. Results: In contrast to the low diversity within and among locations reported by COI, the CR showed a population structure distinguishing between northern (Muga, Fluvià, Daró, Ter, and Tordera rivers) and southern basins (Besòs, Llobregat, Gaià, Francolí, and Ebro rivers). In the southern rivers, a single haplotype, (H1), was present. This haplotype declined in abundance towards the north, being replaced with H2. In the Muga River, native Catalan chub populations showed the fixed H3 haplotype, suggesting strong isolation, while populations from the Daró River contained a private haplotype (H4). In contrast, the presence of a common and single haplotype in southern basins possibly resulted from genetic drift under strong summer droughts. Conclusions: Overall, these results reveal population structuring in S. laietanus and highlight the importance of considering regional differentiation in conservation and management strategies.

Proceedings doi: 10.3390/proceedings2026146048

Authors: Marina Paixão Gil Mario Vinicius Condini Maurício Hostim-Silva Felippe Alexandre Daros

Introduction: Estuaries are dynamic environments that structure fish populations and can be investigated through geochemical signatures recorded in otoliths throughout the lives of individuals. Objective: This study aimed to assess the spatial geochemical differentiation of Genidens genidens, Guri sea catfish, across estuaries in southeastern Brazil using otolith elemental ratios and both univariate and multivariate approaches. Methodology: A total of 68 individuals were sampled from three estuaries (Rio Doce, Ipiranga, and São Mateus), with a subset of 53 individuals (aged 3–5 years) used for ontogenetic comparisons. Otolith microchemistry was analyzed using LA-ICP-MS, generating elemental profiles along the growth axis. Core, edge, and full transect signatures were defined. Data were analyzed using univariate and multivariate approaches, including PERMANOVA and Random Forest for spatial discrimination. Results: Geochemical signatures revealed spatial differentiation among estuaries, with a distinct separation of Rio Doce from Ipiranga and São Mateus (PERMANOVA: Pseudo-F = 20.23; p = 0.001). For individuals aged 3–5 years, no spatial differentiation was detected in the core (p = 0.184), whereas the edge showed significant separation among estuaries (p = 0.001; R2 = 0.434). Random Forest achieved an overall classification accuracy of 82.35%, with the highest accuracy for Rio Doce (95.65%), and identified Ba:Ca as the most important variable (56.0%). Conclusions: The observed spatial differentiation indicates that otolith geochemical signatures reflect regional environmental contrasts among estuaries, with Ba:Ca acting as the main discriminant. The lack of differentiation in the core, in contrast to the edge, suggests that spatial signals are primarily associated with more recent life stages. The high classification performance further supports the ability of multi-elemental signatures to discriminate estuarine systems, although lower accuracy between Ipiranga and São Mateus highlights the influence of environmental similarity. Overall, otolith microchemistry proved effective in detecting spatial structure at a regional scale.

Proceedings doi: 10.3390/proceedings2026146049

Authors: Gabriel de la Hucha Felipe Morcillo Anabel Perdices

Our objective is to assess the potential of ichthyological material from scientific collections for contemporary trophic studies by determining whether stomach contents of freshwater fish preserved in museum collections are well conserved and therefore comparable to those of present-day specimens. Specifically, we examined whether stomach contents from four native species—Squalius alburnoides, Iberochondrostoma lemmingii, Pseudochondrostoma willkommii, and Anaecypris hispanica—housed in the Museo Nacional de Ciencias Naturales (MNCN, CSIC) are suitable for quantitative dietary analyses. Museum specimens were collected in the Guadiana and Guadalquivir basins during spring–summer prior to 1980. Contemporary specimens were captured by electrofishing during spring–summer 2025 in the Bembézar River (Guadalquivir basin). Stomach content from the anterior third of the stomach was identified under a stereomicroscope, and all prey items were categorized. To analyze diet composition and characterize interspecific trophic structure, we assessed multivariate homogeneity of dispersion (PERMDISP) and performed permutational multivariate analyses of variance (PERMANOVA) based on Bray–Curtis distances. SIMPER analyses were used to identify the dietary items contributing most to dissimilarities between historical and contemporary samples for each species. Potential preservation-related biases were further evaluated by comparing the frequency of larval prey categories in museum specimens versus contemporary specimens. Our results indicate: (i) the overall suitability of museum specimens for dietary studies in all species examined; (ii) no evidence of a systematic loss of larval prey items in collection material, suggesting the absence of a generalized degradation bias; (iii) significant dietary differences between contemporary (2025) specimens and historical specimens (pre-1980), which in P. willkommii and I. lemmingii may be attributable to data dispersion, whereas in S. alburnoides these differences may reflect changes in trophic ecology, potentially associated with the introduction of invasive exotic species; and (iv) no significant differences in diet between historical and contemporary specimens of Anaecypris hispanica.

Proceedings doi: 10.3390/proceedings2026146044

Authors: Filipe Ribeiro Rui Rivaes Diogo Ribeiro Mafalda Moncada Diogo Dias Beatriz Castro Christos Gkenas Bernardo Quintella Maria Filomena Magalhães Rui Rebelo Alexandra Marçal Cristina Catita José Lino Costa Martin Čech Lukáš Vejřík Stefano Brignone Pietro Volta

Introduction: The invasive European catfish (Silurus glanis) is actively spreading across Iberian freshwaters, with no effective management measures in place to control its growing abundance or prevent its establishment in new localities. It poses a severe threat to endemic and already endangered species, and is simultaneously a preferred target by few anglers who continuously promote its spread. The LIFE-PREDATOR project aims to stop the spread of European catfish in lentic systems in Portugal and Italy, particularly in protected areas. Objectives: This talk will present the mid-term results of the LIFE-PREDATOR in Portugal, and discuss the difficulties and future challenges to reduce the size of local populations of European catfish. Methodology: The LIFE-PREDATOR team developed several tasks in Portugal: (1) established the reference situation of fish communities in six reservoirs in the Tagus Basin, using scientific fishing, fish telemetry and eDNA-based tools; (2) determined the optimal protocols for sampling catfish; (3) implemented an early detection programme based on warning teams, data-mining and eDNA tools; (4) developed population control actions in four reservoirs; and (5) organised dissemination events for the general public, anglers, and students from kindergarten to university levels. Results: Overall, there is a grim view about recipient communities in the studied lentic systems, which tend to be dominated by invasive fish species, including common carp (Cyprinus carpio), gibel carp (Carassius gibelio), European catfish, pikeperch (Sander lucioperca), European perch (Perca fluviatilis) and largemouth bass (Micropterus nigricans). At least three new localities harbouring catfish were identified from online data-mining and warning teams. A total of 8 tons of catfish were removed by mid-June of 2025, mostly from the Natural Park of International Tagus. Outreach activities were conducted in nearly 60 schools, reaching more than 5000 students. Moreover, 67 general public events have reached more than 4500 people since the project started (September 2023). Conclusions: Despite its positive outcomes, the LIFE-PREDATOR team has encountered challenges in engaging key stakeholders such as anglers, involving local municipalities, and implementing catfish removal actions in remote areas. Difficulties and challenges in catfish management must therefore be debated in order to assure the after-LIFE implementation across Portuguese protected areas.

Proceedings doi: 10.3390/proceedings2026146050

Authors: Xavi Giménez-Borrás Hugo Expósito Roselló Ángela Brotons Eduardo Belda Pilar Risueño Victor Gallego

Introduction: The vulnerable status of endemic Iberian fish like A. iberus and V. hispanica, together with limited knowledge of their reproductive biology, makes understanding temperature effects on hatching essential for defining their thermal limits and guiding conservation in a warming climate. Objectives: The main goals of this study were (i) to describe the embryonic development from fertilization to hatching in both species, and (ii) to evaluate the effect of temperature (20, 25, and 30 °C) on the embryonic development of both species, analyzing their future viability in the face of future climate scenarios. Methodology: Eggs at the earliest embryonic stage were evenly distributed among Petri dishes under controlled laboratory conditions. All dishes contained pH-controlled water with methylene blue to reduce fungal development. The hatching success of A. iberus and V. hispanica eggs was assessed across three temperature treatments (T20, T25, T30). Results: At 20 °C and 25 °C, A. iberus embryos achieved 100% hatching, with no failed eclosions. At 30 °C, however, hatching success declined to 33%, largely due to embryo mortality associated with fungal growth favored by higher temperatures. V. hispanica showed an even stronger temperature-dependent response: hatching was 100% at 20 °C, decreasing to 50% at 25 °C, and only 14% at 30 °C. These results indicate that V. hispanica embryos exhibit lower thermal tolerance compared to A. iberus. Conclusion: The data obtained in this study have helped to improve the limited knowledge available on the reproductive biology of these species, complementing existing information on their reproductive cycle. The experiments conducted at different temperatures have also provided valuable insights into how future climate change scenarios may affect their early stages, particularly during sensitive developmental periods. This information is essential for predicting potential impacts of climate change and can be used to guide the development of new conservation and management measures aimed at reducing threats and improving the long-term conservation prospects of these species, especially in vulnerable or changing habitats.

Proceedings doi: 10.3390/proceedings2026146039

Authors: Xavi Giménez-Borrás Adrián Pérez Ángela Brotons Eduardo Belda Pilar Risueño Victor Gallego

Introduction: Studying the structure and dynamics of living communities is essential from both ecological and wildlife management perspectives. Objective: The main objective of this study was to analyze the fish community structure inhabiting different river sections across several basins in the Mediterranean area. The data collected here contributed to: (i) creating a regional and national reference inventory to assess ichthyological biodiversity; (ii) generating digital cartographic information on species distribution and potential habitats; and (iii) providing scientific data to update national legal protection for governments. Methodology: Fish assemblages were monitored using electrofishing, which ensures reproducible data and long-term comparability. The study period extended until autumn 2025, with intensive sampling at 30 sites across major water bodies in the Valencian Community and selected rivers in Mijares, Turia, Jucar and Palancia basins. Results: The results reveal notable ichthyological richness in the studied basins (Turia, Júcar, Palancia, Mijares), with 12 native species identified. Cyprinidae and Leuciscidae were the most representative families, both in species number and spatial distribution, consistent with their dominance in Mediterranean river systems. Areas with the highest species richness corresponded to the middle and lower river sections and to ecologically valuable coastal wetlands. However, the study also detected 10 invasive alien species, representing 45% of the total fish fauna recorded. This high proportion reflects the significant ecological alteration affecting rivers and wetlands in these basins and underscores the urgent need for management actions to limit the spread of invasive species and reduce their impact on native biodiversity. The most widespread IAS were the bleak (A. alburnus), mainly in the Júcar basin, and the mosquitofish (G. holbrooki), predominantly in coastal wetlands. Conclusions: This study contributes directly to updating the Atlas of Ichthyofauna of the Valencian Community, providing a robust and current information base to support environmental decision-making at regional and national levels. The findings highlight the importance of strengthening proactive conservation measures, particularly in areas where biodiversity is most vulnerable.

Proceedings doi: 10.3390/proceedings2026146045

Authors: Rafael Miranda Javier Oscoz Felipe Morcillo Frederic Casals Andrea Pino-del-Carpio Silvia Perea

The Iberian Peninsula hosts one of the world’s most endemic fish faunas. Its extensive evolutionary, palaeogeographic, and geological history has produced a distinctive freshwater fish fauna. Many of these species have very limited distributions, making them especially vulnerable to habitat disturbance. Past monitoring of this biodiversity has revealed alarming results, indicating that most native Spanish species are at risk. The causes of this serious situation are varied and reflect the ongoing deterioration of freshwater ecosystems. The main pressures faced by populations include pollution, loss of river connectivity caused by hydraulic infrastructure, regulation of watercourses, water extraction, fishing, and the presence of invasive species. Additionally, the effects of climate change worsen the risk of extinction for these populations, particularly through the increased frequency and intensity of droughts and heatwaves. It is evident that current planning models and investments are inadequate to conserve freshwater fish. To prevent the extinction of many populations in Spain, especially Iberian endemics, it is crucial to change the management of aquatic ecosystems and adopt integrated solutions that halt population declines and promote the sustainable use of aquatic resources. The IUCN Red Lists of Threatened Species are vital indicators of biodiversity health and are widely used to guide and structure conservation efforts. These lists, published in the Red Books, result from a thorough evaluation process that employs specific categories and criteria to assess the extinction risk of species, both globally and regionally. This report presents preliminary findings from a monitoring study on the current state of freshwater fish in Spain. The monitoring results reveal that, based on IUCN assessment criteria, two species are classified as extinct (EX), four as critically endangered (CR), eighteen as endangered (EN), and twenty-one as vulnerable (VU). Of fifty-seven species documented, 79% are considered threatened. The project’s final outcome is the development of the Atlas and Red Book of Freshwater Fish of Spain. This resource includes the main native and invasive freshwater and diadromous fish species, offers detailed information on their biological and ecological traits, and provides an up-to-date inventory of records along with an assessment of their conservation status.

Proceedings doi: 10.3390/proceedings2026146040

Authors: Matilde Moreira-Santos Laura Guimarães Cristiano V. M. Araújo

Introduction: The rationale of traditional toxicity assessments, such as fish lethality tests (e.g., OECD TG 203), is to use forced exposure tests to characterise the ecotoxicity of chemicals by deriving concentration–response relationships based on observed physiological effects to estimate environmental risks. This approach assumes that physiological mechanisms, such as detoxification, are the main means that organisms use to minimise contamination effects. However, non-forced exposure approaches, where organisms can freely move along a contamination gradient, show that mobile species like fish can avoid adverse contaminant levels and escape to favourable areas. As populations are exposed to disturbed habitats, direct ecosystem-level effects may occur through population downsizing, even in the absence of individual suffering. Contaminants may thus act as habitat disturbers, regulating fish dispersion patterns by provoking emigration from contaminated areas at concentrations well below lethal levels. Spatial avoidance responses therefore align with a key priority in environmental risk assessment (ERA): progressing beyond standard tests to gain ecological realism when assessing impacts on biodiversity, habitats, ecological processes and recovery. Objective: To increase ecological relevance in ERA while halting animal distress, pain and suffering. This study reviews existing data on fish avoidance tests, with the ultimate goal of discussing their value and fostering their implementation as an ecologically relevant and more humane alternative to fish lethal testing in chemical ERA. Methodology: This review analyses results from studies using two main non-forced multi-compartment exposure systems: linear systems and the bi-dimensional HeMHAS (Heterogeneous Multi-Habitat Assay System), compared with traditional forced exposure tests. Conclusions: Spatial avoidance is generally triggered after short exposure periods (5 min to 48 h) at concentrations causing no mortality. Fish populations may therefore become locally extinct before any deaths occur, as individuals promptly emigrate without physiological impairment. The simplicity of experimental design provides strong potential for standardisation and routine implementation in ERA. Fish avoidance tests represent a key ecologically relevant tool at ecosystem and landscape levels and support the 3Rs (replacement, reduction and refinement) as well as the new 3Rs (reproducibility, relevance and regulatory applicability), helping reduce uncertainty in chemical assessment, as urged by many EU legislations.

Proceedings doi: 10.3390/proceedings2026146037

Authors: Ana Hernández Felipe Martínez-Pastor Fátima Gil Carla Sousa-Santos Elsa Cabrita Victor Gallego

Introduction: Populations of freshwater fish species of the Iberian Peninsula have been declining since the mid-20th century, and several types of actions (from in situ to ex situ actions) have been applied over the past decades. However, limited knowledge about their reproductive biology makes it necessary to investigate different aspects of the reproductive cycle for improving breeding programs. Objective: The main objective of this work was to advance knowledge in the sperm biology of two endemic fish from Portugal rivers, trying to check whether breeding in captivity is a factor able to modulate sperm subpopulations. Methodology: Populations of different endangered leuciscid species (Iberochondrostoma lusitanicum, IL, and Achondrostoma occidentale, AO) were sampled during the spring of 2022 both in captive populations kept at Aquário Vasco da Gama (AVG) and in wild populations (WILD) from different Portuguese rivers. Sperm samples were collected, and sperm motion parameters were assessed by using a CASA system (VSL, VAP, STR, LIN, WOB, ALH and BCF). Results: The application of a two-step cluster analysis yielded four sperm subpopulations (SP1, SP2, SP3 and SP4) in both species. SP1 comprised fast, linear spermatozoa (high VCL, LIN, STR). SP2 contained slow linear cells (low VCL, high LIN, STR). SP3 included fast nonlinear spermatozoa (high VCL, low LIN, STR). SP4 represented slow nonlinear cells, with low values for all three kinematic parameters. Regarding the origin of fish (wild and captive), and for both species, WILD leuciscids showed higher values of linear and fast sperm subpopulation (SP1) than captive fish (AVG), which showed a higher percentage of non-linear subpopulations (SP3 and SP4). Conclusions: In this context, and given that fast and linear spermatozoa (SP1) have traditionally been correlated with high fertilization success in many fish species, these results may indicate that breeding in captivity over a long period of time may affect gamete quality, making it necessary to renew the broodstock from time to time to avoid reproductive problems (i.e., loss of sperm quality and cases of inbreeding).

Proceedings doi: 10.3390/proceedings2026146035

Authors: Mafalda Fernandes Nuno Gomes Carlos Antunes

Introduction: Estuaries are among the most productive ecosystems in the world, holding great ecological and economic importance. As transitional zones between rivers and the sea, they experience abrupt abiotic changes linked to the tidal cycle, as well as seasonal changes related to greater river discharge during periods of higher rainfall. Therefore, salinity and temperature are key factors in structuring communities. These estuarine areas are recognized as nursery grounds, offering an abundance of food and shelter from predators, which creates ideal conditions for juvenile growth. Objective: Intense heatwaves were recorded in northern Spain during 2021 and 2022. This study aimed to understand how environmental factors influence the daily and seasonal dynamics of epibenthic communities and to compare these results with those obtained 40 years ago. Methodology: The epibenthic community in the Minho River estuary was assessed between September 2021 and August 2022 during spring tides at both low tide and high tide. Five trawls were carried out at each tide using a 2-meter-wide beam trawl. Several physical and chemical parameters were evaluated during the sampling process. Results: A total of 10,527 demersal fish and epibenthic crustaceans belonging to 21 species were caught in the sampling area. The structure of epibenthic assemblages was heavily influenced by tidal regimes. Assemblages at low tide had a greater number of taxa. In contrast, high-tide assemblages exhibited significantly higher diversity and evenness. Significant differences were observed between the spring/summer and winter assemblages. A SIMPER analysis revealed that Carcinus maenas contributed most to assemblage dissimilarity, both seasonally and by tide. Furthermore, Echiichthys vipera and Platichthys flesus were the species that contributed most to assemblage dissimilarity in both 1982 and 2021–2022. Conclusions: Compared with historical data, the rise in temperature and salinity, coupled with reduced water flow, has caused a profound restructuring of benthopelagic communities. This is driven by a significant increase in the marine character of the habitat. Substantial taxonomic turnover is evident, characterized by reductions in abundance and increases in the number of taxa sampled, as well as in diversity and evenness.

Proceedings doi: 10.3390/proceedings2026146034

Authors: Miguel Macário João Gago Vanda Andrade Paula Ruivo Maria Oliveira João Oliveira Filipe Ribeiro Abigail Lynch

Introduction: Professional inland fisheries in Portugal remain poorly characterized despite their ecological, social, and territorial relevance. Objective: The objective of this study is to examine the evolution of the biomass catched by inland professional fisheries and determine its economic value. Methodology: This study examines the evolution of declared biomass between 2012 and 2024 and estimates the market relevance of this activity using official catch declarations submitted to the national licensing authority (ICNF). Records were harmonized by species and water body and subsequently aggregated at hydrographic basin level to identify long-term temporal and spatial patterns. Economic estimation was based on a gross production approach combining declared biomass with species-specific price information collected from retail channels and reports from professional fishermen. Changes in species composition were also analyzed to assess whether the observed trends reflect a broader restructuring of freshwater exploitation. Results: The results show a marked interannual variability and a strong spatial concentration of catches, with a limited number of basins (international rivers) accounting for most reported biomass. They also reveal the increasing prominence of non-native taxa in total catches; particularly, the red swamp crayfish, while native migratory species, although represented by lower volumes, maintain high unit prices and make a relevant contribution to total revenue. This contrast suggests that recent changes in freshwater catches are not merely quantitative, but also structural, with implications for ecological status, the growing dependence of the fishery on invasive species, and the territorial distribution of economic returns. Conclusions: By combining official catch declarations with market-based valuation, this study provides an updated overview of the recent evolution of professional freshwater exploitation in Portugal and offers a useful basis for fishery governance, monitoring programmes, and future discussions on conservation, licensing, and basin-scale management.

Proceedings doi: 10.3390/proceedings2026146031

Authors: Rafael Schroeder Esteban Avigliano Alejandra V. Volpedo Roberta Callico Fortunato Rodrigo Sant’Ana Martin C. Dias Felippe A. Daros Pedro M. Barrulas José A. Mirão Alberto T. Correia

Introduction: The Lebranche mullet (Mugil liza) is a commercially important fish species in southeastern and southern Brazil, which serves as the primary spawning ground for the Southern stock that supports the Brazilian industrial seine fleet. However, this stock’s distribution extends into Argentine waters (northern Patagonian shelf), and the connectivity between mullets caught in Brazil and their breeding areas across South America remains poorly understood. The authors hypothesized that adult mullets landed by the Brazilian fleet consist of two distinct groups: A local group originating in Brazilian waters (BR1) and a migratory group (BR2) that uses nursery areas in Argentina (AR). BR2 presumably returns to its original nursery grounds after spawning, to recover reproductive tissues, following a different migratory pattern than BR1. Objectives: To test this, the study analyzed the micro-chemical life history of 134 otoliths from mullets aged 0+ to 11 years using LA-ICP-MS. Methodology: Two elemental ratios (Ba/Ca and Sr/Ca) were measured from the otolith core to the edge and modelled using a generalized additive model for scale and shape (GAMLSS). Life history transitions were evaluated by pairwise comparisons of fitted values among ages. Results: GAMLSS showed that Ba/Ca ratios differed significantly among groups (AR ≠ BR1 ≠ BR2). In contrast, Sr/Ca ratios were similar between AR and BR2 during the first four years of life, significantly differing from those of BR1. Using empirically established thresholds for estuarine vs. marine habitats, the study determined that BR2 individuals leave nursery areas between ages 5 and 6, migrate back around age 8, and live there one last time after age 10 (the species’ maximum age). BR1 leaves nurseries after age 4 and returns between ages 5 and 6, exhibiting a shorter reproductive cycle. Importantly, the analysis of reproductive tissue mass showed that the weight after age 7 approximately matched the weight at age 3. After recovery, reproductive tissues doubled in weight before the second migration to spawn at sea. Conclusions: These findings provide crucial insights into M. liza’s life cycle, highlighting the need for shared stock management not only with neighboring nations (Argentina and Brazil) but also on a regional scale.

Proceedings doi: 10.3390/proceedings2026146029

Authors: Juan M. Molina Andreas Kunzmann Rita A. Costa Teresa Modesto Alexandra Alves Pedro M. Guerreiro

Introduction: Coastal fishes can adapt to water warming and hypoxia; however, acute tolerance does not necessarily predict longer-term performance and survival. This may be especially important in sedentary, site-faithful species with limited escape to escape increasingly unfavorable habitats. We assessed the climate-related stress responses of the Lusitanian toadfish, Halobatrachus didactylus, a benthic estuarine fish from the Northeast Atlantic, to water warming and hypoxia. Objectives: We aimed to determine the aerobic energy budget, thermal limits (CTmax), and critical oxygen tension (Pcrit), as well as blood indicators of metabolism, altered physiology and systemic stress, as proxies for whole-organism homeostatic state, thereby informing future ecophysiological assessments and bioindicator development in a context of environmental change. Methodology: We determined standard, routine, and maximum metabolic rates; aerobic scope; and critical thermal maximum (CTmax) and critical oxygen (Pcrit) thresholds on a set of 134 individuals ranging from 12 to 160 g in weight. On a different set of individuals (n = 48; 76.3 ± 2.6 g; 16.1 ± 0.18 cm), we simulated 30 days of seasonal scenarios combining low and high temperature with normoxia or hypoxia, followed by integrated metabolic, hematological, biochemical, and multivariate analyses. Results: Acute trials showed high short-term resilience: H. didactylus had an exceptionally low standard metabolic rate and routine metabolic rate, high CTmax (34.82 ± 0.66 °C), and strong hypoxia tolerance (Pcrit 0.59–1.97 mg O2 L−1), although smaller individuals were more sensitive. After 30 days, however, warming more than doubled standard and routine metabolic rates, while warm hypoxia reduced metabolic output relative to warm normoxia, consistent with metabolic depression under compounded stressors. This treatment also showed shifts in glucose, liver mass, red blood cell count, and hematocrit, identifying warm, oxygen-poor water as the most physiologically costly scenario for this species. Conclusions: Together, these results show that high acute tolerance does not guarantee resilience to climate change. In sedentary fishes, survival may depend less on surviving extremes than on maintaining energetic balance, oxygen transport capacity, and physiological homeostasis in increasingly warm, oxygen-poor coastal habitats.

Proceedings doi: 10.3390/proceedings2026146042

Authors: Renan Leite Filipe Romão Isabel Boavida José Maria Santos Paulo Branco Ana Quaresma

Introduction: Freshwater ecosystems are among the most threatened worldwide, with river fragmentation, primarily caused by dams and weirs, identified as a major driver of biodiversity loss. This issue is particularly acute in Europe, where more than one million instream barriers disrupt longitudinal connectivity and compromise the movement of migratory fish. Fishways are widely implemented to mitigate these impacts, yet attraction efficiency at fishway entrances remains poorly understood, especially for Iberian potamodromous cyprinids, a group facing severe conservation pressures. Objective: This study aims to investigate how hydraulic conditions and social context influence the attraction and passage behavior of Luciobarbus bocagei, a rheophilic potamodromous cyprinid endemic to the Iberian Peninsula, in an experimental Vertical slot fishway (VSF) entrance. Methodology: Experiments were conducted in a controlled flume equipped with a VSF entrance design. Two hydraulic scenarios were tested, a Low Head Drop (LD) and a High Head Drop (HD), under a constant discharge of 34 L/s. A computational fluid dynamics (CFD) model was used to characterize and compare the flow field hydrodynamics. Fish were tested individually and in groups of three to assess the role of social dynamics. The metrics collected included time to first approach, first attempt, time to first successful passage, attraction efficiency, and passage efficiency. Cox proportional hazards models were applied to evaluate treatment effects. Results: Preliminary results showed that social context influenced fish attraction behavior. In the two hydraulic scenarios, individuals tested alone tend to exhibit lower likelihoods of approaching, attempting, and successfully negotiating the fishway compared to fish in schools. Delays were also evident for attempts and successful passages, with LD_Ind performing the worst. Conclusions: These findings highlight the importance of hydraulic conditions and social behavior in shaping attraction efficiency. They underscore the need to integrate species-specific behavioral ecology into fishway design, operation, and attraction assessment, acknowledging that fish attractivity is influenced by environmental and ecological factors beyond fishway structure, particularly in Mediterranean river systems where fragmentation pressures are high and potamodromous cyprinids are at risk.

Proceedings doi: 10.3390/proceedings2026146027

Authors: Sandra Barca Rufino Vieira-Lanero Fernando Cobo Carlos M. Alexandre Pedro R. Almeida Esmeralda Pereira Silvia Pedro Gonçalo Rodrigues Luís Macedo Luís Silveirinha Gonçalo Brás Beatriz Mendes Célia Laranjeira Luísa Sousa Pedro Marques Isabel Pragana

LIFE REVIVE aims to restore ecological status and ecosystem services in the Lima and Vouga river basins (NW Iberian Peninsula), where hydromorphological alteration and hydropower-driven flow regulation are major causes of water bodies failing to reach Good Ecological Status under the EU WFD. The project targets key pressures such as longitudinal fragmentation by weirs and dams, artificial flow regimes, degradation of spawning substrates, and the spread of invasive aquatic plants, which strongly affect fish communities, including sea lamprey, salmonids, and other diadromous species. Technically, the project combines barrier removal or eco-adaptation, nature-like fish passes, and spawning-habitat renaturalisation with optimized environmental flow regimes (EFR) downstream of important hydropower systems, explicitly accounting for present and future hydroclimatic scenarios. Multi-scale ecohydrological modelling (species distribution models, habitat suitability models, GLM/GAM approaches) will quantify fish–flow–habitat relationships and support the definition of operational EFR guidelines that balance ecological requirements with hydropower and agricultural constraints through joint work with the main Portuguese hydropower operator, EDP. Impact evaluation is structured around a rigorous BACI monitoring design in intervention and control tributaries, using standard WFD biological indices for fish and aquatic/riparian vegetation, hydromorphological indices (HQA, HMS, RHS), and project-specific Key Performance Indicators for water quality, biodiversity, and habitat. Expected outcomes include the restoration of at least 51 km of rivers towards free-flowing conditions, reduced hydromorphological pressure in more than 20 km of heavily modified river stretches, and measurable increases in the distribution and abundance of fish species and native vegetation. A strong communication and capacity-building programme underpins public engagement, while a decision matrix for barrier prioritization, technical workshops, and pilot replications in additional basins (e.g., Alva, Mouro, Deva, and Tea in Galicia) are designed to maximize transferability, policy uptake, and long-term sustainability of the solutions beyond the project lifetime.

Proceedings doi: 10.3390/proceedings2026146047

Authors: Felippe A. Daros Kauan F. Xavier Estella R. S. Santos Priscila Capizani Arthur Q. Diniz Wanilton P. Batista Marina Paixão Gil Julia P. Altafin

Introduction: The Cananéia–Iguape Lagoon Complex, part of the Lagamar Mosaic of Conservation Units, comprises interconnected ecosystems that facilitate the dispersal and exchange of larvae, juveniles, and adults across habitats. This connectivity is a vital ecological process, driving the demographic linkage of local populations. Due to its commercial importance and abundance, the fat snook (Centropomus parallelus) serves as an ideal model for connectivity studies in this region. This study evaluated the otolith fingerprints of fat snook nursery areas within an estuarine complex using elemental chemical signatures. Methodology: Otoliths from 24 juveniles (n = 6 per site) were sampled across four nurseries: Ariri (AR), Itapanhapima (IT), Subauma (SU), and Iguape (IG). Multi-elemental signatures (Na, Mg, P, K, Ca, Mn, Sr, Ba, and Pb) at the otolith edge were measured via Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS). Results: Multivariate analysis (PERMANOVA, p < 0.05) revealed significant chemical differences between nurseries, corroborated by pairwise tests. Canonical Analysis of Principal Coordinates (CAP) with leave-one-out cross-validation successfully assigned individuals to their collection sites with accuracies of 55% (AR), 72% (IT), 94% (SU), and 88% (IG), achieving a 78% global reclassification rate. CAP results distinguished two primary groups: the southern nurseries (AR/IT) and northern nurseries (SU/IG). This spatial separation was primarily driven by Sr:Ca and Ba:Ca ratios, reflecting the higher marine influence in the south versus freshwater input from the Ribeira de Iguape River in the north. Conclusions: These findings provide critical data to support public policies for the conservation of coastal ecosystems and the management of associated fish stocks.

Proceedings doi: 10.3390/proceedings2026146022

Authors: Paulo Branco Pedro Segurado José Maria Santos Maria Teresa Ferreira Daniel Mameri Tamara Leite António Tovar Faro Gonçalo Duarte

Introduction: Freshwater systems are increasingly being impacted by a plethora of pressures. Freshwater fish are thus periled, urging the need to investigate the drivers of population decrease to better counteract them, in order to provide some conservation relief to these pressured species. Methodology: To facilitate freshwater research, the Dammed Fish Project developed a series of free tools that simplify procedures and facilitate the access of correct data. Results: RivTool+ is a free software that evolved from RivTool (used in over 75 countries) and that integrates new functions and acts as a tool hub to host additional software apps. The computing engine of RivTool, that allows along the river network calculations and summarizations, is now able to be used by new tools. RivConnect—River network connectivity app that allows graph-based quantification of structural and functional connectivity, using several metrics and understanding network directionality. RivFish—App that contains the corrected, spatially and taxonomically, occurrence, at the basin and sub-basin level, of more than 600 native freshwater fish species of Europe. RivOpt—Optimization tool that allows for river network connectivity restoration optimization. RivOpt accounts for conflicting multiple objectives and is able to deal with different restoration actions for each barrier (removal, partial removal, fishway construction and retrofitting or no action). Conclusions: Dammed Fish tools facilitate research procedures and access to verified data, improving the information baseline, increasing the accuracy of results and accelerating research. Thus, it contributes to an improved understanding of the mechanisms controlling species vulnerability and contributes to their conservation.

Proceedings doi: 10.3390/proceedings2026146028

Authors: Filipe Romão Ana L. Quaresma Susana D. Amaral Renan Leite Isabel Boavida Francisco J. Bravo-Córdoba Francisco J. Sanz-Ronda António Pinheiro José M. Santos

Introduction: The restoration of river connectivity through fishways is essential for the conservation of native freshwater fish, yet it may inadvertently facilitate the upstream spread of non-native invasive species. This trade-off is particularly relevant in Iberian river systems, where invasive cyprinids pose a growing ecological threat. Objective: In this study, we evaluated the potential for selective fish passage in a full-scale vertical slot fishway (VSF), aiming to promote native species movement while limiting invasive taxa. Methodology: Experimental trials were conducted with the common carp (Cyprinus carpio), a widespread invasive species, and the results were compared with those of the native Iberian barbel (Luciobarbus bocagei). Two fishway configurations were tested, both with high slope (15.2%) and high turbulence (volumetric power dissipation >150 W m−3), differing in water depth (0.55 m and 0.80 m). Fish passage performance was assessed through behavioural metrics, including motivation to attempt passage, ascent success, and transit time, using a time-to-event framework. Hydrodynamic conditions were characterised through computational fluid dynamics modelling. Results: The results revealed marked interspecific differences. Common carp exhibited significantly lower motivation to initiate passage and extremely limited success: no individuals ascended the shallower configuration, and only one ascended the deeper configuration. In contrast, Iberian barbel demonstrated high motivation and passage success under both configurations, particularly in more turbulent conditions. Conclusions: These findings suggest that manipulating key hydraulic parameters can create selective passage conditions that favour rheophilic native species while hindering limnophilic invasive taxa. This ecohydraulic approach offers a promising strategy to reconcile the restoration of longitudinal connectivity with the control of biological invasions. Nevertheless, further research under field conditions and across a broader range of species is required to validate and generalise these findings.

Proceedings doi: 10.3390/proceedings2026146021

Authors: Ana Quaresma Susana D. Amaral Rui Rivaes Diogo Dias Diogo Ribeiro Filipe Ribeiro Isabel Boavida Filipe Romão

Introduction: Freshwater ecosystems are increasingly threatened by river fragmentation caused by the accumulation of small barriers such as weirs. These structures disrupt longitudinal connectivity and hinder fish movements, restricting access to essential habitats (e.g., spawning) and affecting biodiversity and ecological river functions. Though many of these structures are obsolete and their removal is increasingly promoted as a river restoration measure under the EU Biodiversity Strategy and the Nature Restoration Law, the ecological implications of barrier removal are not totally positive. One of the most pressing concerns is the unintended spread of Invasive Alien Species (IAS), which may expand upstream once a barrier is eliminated. In this context, selective barriers are gaining attention as a promising management tool to balance ecological restoration goals with IAS control. By carefully designing or adjusting hydraulic features such as head drops, it may be possible to allow passage for native species while restricting the movement of invasive fish. However, despite its potential, selective barrier design remains underexplored. Objective: This research aims to address this gap by testing how head drops influence the upstream movement of Iberian straight-mouth nase (Pseudochondrostoma polylepis), a native leuciscid, and the European perch (Perca fluviatilis), an IAS rapidly expanding across the Iberian Peninsula. Methodology: Laboratory experiments were conducted in an indoor ecohydraulic flume (6.5 × 0.7 × 0.7 m) at the Hydraulics Laboratory of IST. A single weir structure whose downstream water level was adjusted to create three distinct head drops—11, 18, and 25 cm (configurations A, B, and C, respectively)—was tested. Tests were performed using one specimen of each species that were allowed 15 min acclimation to the flume conditions followed by a 60 min trial. The number of approaches, attempts and successful upstream passages were recorded. Additionally, the flow-field characterization was performed using an Acoustic Doppler Velocimeter (ADV; Nortek-AS Vectrino 10 MHz). Results: Preliminary results indicate a strong capability of the native nase to overcome two of the tested head drops, with four and two successful passages recorded for configurations A and B, respectively. In contrast, the invasive species showed no successful passages under these conditions. For configuration C, no successful passages were observed for either species. Conclusions: These results highlight the potential of selective weir designs to promote river connectivity for native species while helping prevent the upstream expansion of invasive fish.

Proceedings doi: 10.3390/proceedings2026146033

Authors: Emanuel Santos Sílvia F. Gregório Rita A. Costa Juan M. Molina Pedro M. Guerreiro

Introduction: Climate warming and drought are intensifying thermal stress in Mediterranean freshwater systems, potentially favoring invasive fish with broad physiological tolerance. Extended environmental tolerance and increased aerobic scope are indicative of the potential to sustain, perform and disseminate in challenging conditions. Objective: We aimed to determine the thermal scope of the invasive Australoheros facetus inhabiting southern Portuguese drainages using an array of physiological proxies. Methodology: We evaluated the thermal biology of the species across a wide temperature gradient to test how warming affects metabolic performance, thermal tolerance, and biochemical status. Fish collected from Algarve watercourses were exposed to 5, 10, 15, 20, 25 and 35 °C (n = 15 per condition, 10–60 g) for at least a week, and intermittent respirometry was used to determine standard metabolic rate (SMR), maximum metabolic rate (MMR) and aerobic scope (AS). Group Q10 was derived from metabolic rates. Plasma and tissue biomarkers of energy metabolism and oxidative stress were analyzed. Critical thermal maximum (CTmax) was assessed in fish acclimated for a week at 10, 20 and 30 °C (n = 10) using a 1 °C/min thermal ramp. Results: Intermediate temperatures (15–25 °C) supported the best overall physiological performance, combining stronger aerobic capacity with higher antioxidant protection. In contrast, 30–35 °C imposed clear physiological costs: maintenance metabolism increased disproportionately, aerobic scope declined, and cellular protection weakened, indicating the onset of heat stress. Despite this, A. facetus showed marked thermal plasticity, with CTmax increasing significantly with acclimation temperature. Fish acclimated to 30 °C had higher CTmax than fish acclimated to 20 °C and 10 °C, although the thermal safety margin decreased progressively as the acclimation temperature rose. Liver antioxidant activity also peaked at intermediate temperatures and declined at the warmest treatments, reinforcing the mismatch between acute tolerance and sustained performance. Conclusions: These results show that A. facetus is highly heat tolerant but that tolerance comes with energetic and cellular trade-offs near upper thermal limits. Despite this limitation at extreme conditions, the combination of broad tolerance and functional performance under warm intermediate conditions may help to explain its invasion success and stand as a competitive advantage in increasingly hot low-flow Iberian freshwater ecosystems.

Proceedings doi: 10.3390/proceedings2026146020

Authors: Cristina Igartua Francisco Baldó Ignacio Ruiz-Jarabo

Introduction: Sharks are key species in marine ecosystems, and their conservation is a priority across European waters. However, several fisheries unintentionally capture sharks as bycatch, raising concerns about their post-capture survival. In the Gulf of Cadiz, demersal trawl fisheries frequently capture the catsharks Galeus atlanticus and G. melastomus. Objective: This study aimed to assess the short-term survival rates of these two species following trawl capture and to identify potential blood biochemical markers predictive of survival. Methodology: Fieldwork was conducted aboard an oceanographic research vessel over two spring seasons. Standarized demersal trawl hauls of 1-h duration were performed. Immediately after capture, individuals were transferred to onboard seawater tanks, where their recovery was monitored for 24 h. Blood samples were collected at two time points: immediately after capture and after the 24-h recovery period. Biochemical parameters associated with secondary stress responses were analyzed. Results: Survival rates were high for both species, reaching 88 ± 8% for G. atlanticus and 90 ± 4% for G. melastomus. Blood analyses indicated a clear physiological recovery in all surviving individuals after 24 h, evidenced by the normalization of stress-related parameters. Notably, interspecific differences were observed in certain biochemical markers after capture, including amino acids and lactate concentrations, suggesting species-specific responses to capture stress. Conclusions: These findings provide valuable insights into the resilience of demersal catsharks to trawl-induced stress and highlight the potential of blood biomarkers as a tool for predicting post-capture survival. The results support the development of evidence-based onboard handling protocols aimed at maximizing the survival of incidentally captured sharks. Such measures can contribute to more sustainable fisheries management and the conservation of vulnerable elasmobranch species in European waters.

Proceedings doi: 10.3390/proceedings2026146030

Authors: Luís Pereira Ulisses M. Azeiteiro Carlos Antunes

Introduction: A diverse ichthyofauna is supported by the Lima River in northern Portugal. Despite its ecological significance, Ramsar-protected wetlands status and Natura 2000 site, the system remains among the least studied in the Iberian Peninsula. Objective: This study characterises the fish assemblage of the Lima River and some of its tributaries. It examines the composition and abundance of species, as well as key biological parameters, across the river’s freshwater and estuarine sections. Particular attention is given to the balance between native and exotic taxa, and to the threats facing the native ichthyofauna. Methodology: Between 2021 and 2023, 3242 individuals belonging to 15 species were sampled using fyke nets, trammel nets, and electrofishing at 13 sites along the river system. Results: Native species accounted for 51.1% of the total catch. This comprised resident freshwater taxa, such as Pseudochondrostoma duriense, Achondrostoma oligolepis, Luciobarbus bocagei, Squalius carolitertii, Cobitis atlantica, Gasterosteus aculeatus, and resident Salmo trutta, alongside diadromous species, namely Chelon ramada, Petromyzon marinus, Alosa spp., migrant Salmo trutta and Anguilla anguilla. Exotic species accounted for 48.9% of the total catch, with four non-native taxa being recorded: Lepomis gibbosus, Micropterus salmoides, Carassius auratus and Gobio lozanoi. This reflects the extent of the biological invasion pressure on this system. Analysis of the stomach contents of Salmo trutta revealed active predation of non-native species. Plastic debris was detected in 1.1% of Salmo trutta stomachs, which evidences that anthropogenic pollution has reached freshwater feeding habitats. The first recorded instance of the invasive nematode Anguillicola crassus in the Lima River, where 84.8% of the eels sampled exhibited moderate-to-severe swim bladder damage, highlights the vulnerability of native species to biological invasions. Conclusions: Biometric analyses and condition factors suggest that the fish community is under cumulative anthropogenic stress, caused by factors including river fragmentation due to three dams and traditional fishing weirs. The near-equal representation of native and exotic species in catches indicates that the freshwater fish community is under significant invasion pressure, which has direct consequences for the conservation of the native ichthyofauna. These findings establish a crucial baseline for the evidence-based management of an Iberian river system that is ecologically important but data-poor.

Proceedings doi: 10.3390/proceedings2026146025

Authors: Juan Carlos Arronte Ana Antolínez Rafael Bañón Francisco Velasco

Introduction: Records of rare, deep-water, and non-indigenous fish species are of growing interest in marine biodiversity research because they refine regional inventories, improve taxonomic knowledge, and provide valuable evidence of ecological change. In regions supported by long-term monitoring programs, such findings are especially relevant, as they help detect unusual occurrences and document changes in species composition over time. Objective: The aim of this communication is to present recent records of fish species new to science and new to Spanish waters, together with a non-indigenous species, all from Galician and Cantabrian waters (northern Spain), while emphasizing the importance of scientific surveys and complementary local observations in their detection. Methodology: The material examined was collected during the annual demersal trawl surveys conducted by the Instituto Español de Oceanografía (IEO-CSIC) on the northern Spanish continental shelf (DEMERSALES), as well as during two multidisciplinary surveys carried out on the Galicia Bank in 2010 and 2011. An additional specimen was obtained from a local recreational fisher off Asturias. In all cases, species identification was based on an integrative taxonomic approach combining morphological examination and molecular analyses (COI barcoding). Results: Three species new to science were identified: Gaidropsarus gallaeciae (Gadiformes: Gaidropsaridae), Notacanthus arrontei (Notacanthiformes: Notacanthidae), and Neoscopelus serranoi (Myctophiformes: Neoscopelidae). In addition, Lyconus brachicolus (Gadiformes: Lyconidae) and Lipogenys hyalovelanum (Notacanthiformes: Notacanthidae) were recorded for the first time in Spanish waters. A specimen of Diapterus brevirostris (Perciformes: Gerreidae), native to the tropical and subtropical Pacific coast of America, was also identified off Asturias. Owing to its small size and to the proximity of the commercial port of Gijón, ballast water is considered the most plausible vector for its introduction into the Cantabrian Sea. Conclusions: These records illustrate the value of long-term oceanographic surveys for detecting rare and deep-water fishes and confirm the usefulness of integrative taxonomy for robust species identification. They also highlight the complementary role of fishers and citizen observers in documenting biodiversity change and detecting non-indigenous species in Spanish waters.

Proceedings doi: 10.3390/proceedings2026146014

Authors: Telma Esteves Fernanda Malhão Célia Lopes Eduardo Rocha

Introduction: The 3 Rs principle advocates developing alternative, biologically relevant models. Thus, 3D fish liver in vitro models have been increasingly used for ecotoxicological studies. We previously optimized spheroids from the rainbow trout non-tumoral liver cell line RTL-W1 and employed them to assess the effects of aquatic pollutants. Although they demonstrated potential for assessing ecotoxicological effects, further optimization is warranted to enhance their physiological relevance. Incorporating an extracellular matrix (ECM), such as collagen, has been shown to be a promising strategy to improve spheroids’ structural organization and functionality. Objective: This study aimed to optimize 3D culturing conditions of RTL-W1 spheroids by evaluating the effects of collagen supplementation on viability, morphology, and functional response. Methodology: Spheroids from the RTL-W1 cell line (60,000 cells per well) were cultured in 96-well ultra-low attachment (ULA) plates at 18 °C. After spheroids’ formation, rat tail collagen was supplemented at concentrations of 15 (C15), 30 (C30), and 60 (C60) µg/mL at culture days 7, 8, and 9. Spheroids were collected at two sampling days (10 and 14). Viability was assessed using alamarBlue and lactate dehydrogenase (LDH) assays, while morphology was assessed by optical microscopy. Collagen penetration was evaluated using Masson’s trichrome staining technique. Protein expression of cytochrome P450(CYP)1A was assessed by quantifying immunocytochemistry staining using an anti-CYP1A antibody. Results: On day 10, LDH leakage decreased in C15 and C60, compared with the control, whilst C15 spheroids showed lower absorbance levels in the alamarBlue assay. On day 14, LDH showed no significant differences; however, C30 and C60 had higher alamarBlue absorbance, indicating greater metabolic capacity. Spheroid morphology appeared intact in all conditions. Masson trichrome revealed collagen fibrils at the periphery of the spheroids, especially in C30 and C60, indicating that spheroids incorporated collagen. CYP1A immunostain was present in all conditions, localized in the spheroids’ border, and tended to be higher when supplementation occurred in earlier days. Conclusions: Our results suggest that RTL-W1 spheroids interacted with the collagen matrix and appeared to functionally improve. Data suggest that incorporating ECM may increase the complexity and physiological relevance of RTL-W1 spheroids, thereby better supporting mechanistic and ecotoxicological applications.

Proceedings doi: 10.3390/proceedings2026146024

Authors: Javier Martín-Gallardo Patrick Reis-Santos César Megina Bronwyn May Gillanders José Carlos García-Gómez Juan Miguel Miró

Introduction: Otoliths have been widely used in recent years as tracers of fish life history, ranging from visual aging to chemical analyses that reconstruct environmental conditions, migration patterns, and metabolic changes. Yet, Iberian endemic or endangered species are understudied. This study focuses on Andalusian barbel (Luciobarbus sclateri), endemic to the southern half of the Iberian Peninsula. Objective: The aim was to evaluate whether otolith chemical profiles can simultaneously support age estimation and reveal the impact of environmental variations, particularly hypoxia. Methodology: Fish were caught in two sites with different environmental properties, including strong hypoxia: the Guadalquivir estuary and the dock of Seville (which is isolated from the main river channel by a ship lock and could, therefore, be used as a control). Otolith chemical composition was analyzed from core-to-edge transects with a laser-inductively coupled plasma mass spectrometer (LA ICP-MS). Results: Patterns of variation in Mg and Mn in relation to hypoxia and environmental conditions are discussed. We visually counted growth rings in the sections, and we found a strong correlation (R2 = 0.904) in Mg:Ca peaks with growth rings. Body condition, assessed using Fulton’s condition factor (K), differed between sites, with fish from the estuary exhibiting a lower condition than those from the dock. Conclusions: The strong correlation between counter growth rings and Mg:Ca peaks suggests that chemical analysis could be used as a valid method for supporting aging. The pattern of lower condition in fish from the estuary is consistent with persistent hypoxic events documented in the estuary but not within the dock environment. This whole approach provides a powerful framework to assess habitat quality and support conservation of L. sclateri in the Guadalquivir estuary.

Proceedings doi: 10.3390/proceedings2026146026

Authors: Alexandra Bento Tânia Cordeiro João Soares Carrola Carla Gonçalves

Introduction: Portugal is, historically, one of the countries with the highest fish consumption worldwide, reflecting strong cultural and dietary traditions. However, shifts in food systems, economic conditions, and globalization may have altered its availability and nutritional contribution to population’s dietary intake over the time. Understanding these long-term dynamics is essential to inform public health and food policy strategies. This work aims to analyze temporal trends and identify structural changes in fish availability in Portugal between 1961 and 2023. Methodology: Data were obtained from FAOSTAT Food Balance Sheets for the period 1961–2023. Fish availability was expressed in grams per capita per day, alongside energy and macronutrient contributions. Descriptive statistics were calculated. Temporal trends were assessed using segmented linear regression models, considering structural breakpoints in 1975, 1986, 2001, and 2014. Model significance was evaluated using ANOVA. Results: Mean fish availability was 147.36 g/capita/day (SD = 26.58), ranging from 67.53 to 195.84 g/capita/day. Fish contributed on average 77.28 kcal/day, 13.25 g/day of protein, and 2.48 g/day of fat. The segmented regression model was statistically significant (p = 0.029), explaining 16.7% of the variability. Significant changes in trends were observed after 1975 (β = −2.185; p = 0.043), indicating a decrease, followed by a significant increase after 1986 (β = 5.164; p = 0.007), and a subsequent decline after 2001 (β = −4.163; p = 0.033). No significant changes were identified after 2014 (p = 0.684). Conclusions: Fish availability in Portugal shows marked structural changes over time, associated with probability, socio-economic and political transitions. Despite fluctuations, fish remains a nutritionally relevant component of the Portuguese diet. These findings highlight the importance of considering long-term trends in food availability when designing nutrition and sustainability policies.

Proceedings doi: 10.3390/proceedings2026146023

Authors: Paulo Branco Pedro Segurado José Maria Santos Maria Teresa Ferreira Daniel Mameri Tamara Leite António Faro Gonçalo Duarte

Introduction: Fragmentation is potentially the most significant pressure affecting European rivers. With the projected number of barriers exceeding 1 million for the EU alone, the quantification of river network connectivity is of extreme practical importance. The Nature Restoration Regulation aims to restore connectivity by increasing the length of free-flowing rivers by 25,000 km across Europe. In this work, we quantify connectivity for European river basins, quantify connectivity affectations and account for ecological status while projecting potential restoration outcomes. Methodology: We used RivTool and RivConnect to manage data across European river basins and to quantify connectivity using graph-based metrics. For this, we validated natural and artificial barrier position and used European-wide datasets for navigation routes, railways and highways to account for additional connectivity impacts. Results: River connectivity in Europe is severely impaired by barrier placement and infrastructure development. The integration of ecological status shows a generalized decrease in potential connectivity. Conclusions: River connectivity quantification needs to be an integrative process and must account for natural and artificial connectivity as well as habitat quality and quantity. It is clear that single-use measures are ineffective. If we enhance connectivity without improving ecological status, the outcomes will lack effectiveness, as will the reverse solution. Basin-wide, data-diverse approaches to connectivity enhancement planning should be the norm and not the exception. Nevertheless, this is, to our knowledge, the first integrated assessment of river network connectivity of European river basins that integrates natural and artificial barriers, additional connectivity affections and ecological quality.

Proceedings doi: 10.3390/proceedings2026146017

Authors: Juan de María-Arnaiz Francisco Javier Bravo-Córdoba Ana García-Vega Juan Francisco Fuentes-Pérez Francisco Javier Sanz-Ronda

Introduction: The upper Arlanza River (Duero Basin, Burgos, Spain) hosts a genetically distinct local lineage of brown trout (Salmo trutta fario), the “Arlanza strain”, largely free from hatchery-derived introgression, alongside other native cyprinids of conservation concern, including the Iberian chub (Achondrostoma arcasii, Vulnerable—IUCN). The river also supports the Iberian desman (Galemys pyrenaicus, Endangered—IUCN) and Eurasian otter (Lutra lutra). Despite these values, the study reach presents multiple transverse obstacles limiting longitudinal connectivity and degraded riparian cover in critical sections due to livestock erosion, compromising habitat quality for all species. Objective: This study aimed to design engineering interventions to improve fluvial and riparian habitat in a 4 km reach of the upper Arlanza River, restoring longitudinal connectivity and thermal refuge availability while strictly preserving the genetic integrity of the native Arlanza trout strain. Methodology: The reach was characterised through electrofishing surveys, riparian quality assessment (modified RQI index), hydraulic refuge evaluation (IR index), and hydrological analysis based on a 30-year flow record. Brown trout population dynamics were modelled using dimP 1.0 software, with a comparative analysis between upstream (Quintanar de la Sierra village) and downstream (Vilviestre del Pinar village) sampling points to identify connectivity bottlenecks. Engineering works were scheduled to avoid reproductive periods of all target species. Results: The upstream population showed a rejuvenated age structure (density: ~1.40 ind/m; mean length: 12.0 cm), consistent with good spawning conditions but limited growth capacity due to cold temperatures and low summer flows. The downstream point exhibited a severely reduced population (~0.10 ind/m), indicating marked loss of connectivity and habitat degradation. Priority intervention zones were identified in the Camping and lower Prado Mayor sub-reaches. Proposed measures included weir notching to restore fish passage, livestock watering points to reduce bank erosion, and riparian restoration by planting native species (Populus tremula, Betula alba, Salix spp.) protected with fences. Conclusions: Restoring longitudinal connectivity and riparian cover in the upper Arlanza River are essential to protect the genetically valuable Arlanza trout strain, the endangered G. pyrenaicus, and other native fish species, providing a transferable framework for headwater fluvial restoration that jointly addresses biodiversity conservation and genetic resource protection.

Proceedings doi: 10.3390/proceedings2026135004

Authors: Kjell Hausken

The 1st International Electronic Conference on Games (IECGA 2025) was held virtually from 15 to 16 October 2025 [...]

Proceedings doi: 10.3390/proceedings2026146016

Authors: António Martinho Simone Varandas

This study presents the revision of the Rabaçal River Recreational Fishing Area Management Plan (ZPL), implemented in 2020, aiming to evaluate its effectiveness and identify the need for adjustments after five years. The study area includes part of Montesinho Natural Park, covering water bodies upstream of the Vale de Armeiro Reservoir (RH3—Douro Basin), excluding the Assureira River sub-basin. The methodology followed the initial study design, with electrofishing conducted at ten stations (30 surveys). Hydromorphological and riparian conditions were assessed using the River Habitat Survey (RHS), enabling the calculation of the Riparian Quality Index (RQI), Habitat Modification Score (HMS), and Habitat Quality Assessemt (HQA). Results indicate high habitat diversity and overall good-to-excellent hydromorphological quality, although they are locally affected by human pressures and global change. Brown trout (Salmo trutta) was recorded at all sites, showing wide spatial distribution. Population structure was dominated by young individuals (≤2 years; 70%), indicating high recruitment rates. However, growth patterns and reduced body condition suggest that habitat features, particularly flow regime and riparian quality, are influencing population dynamics, highlighting the need to explicitly integrate habitat–population relationships into management measures. A notable expansion of the invasive signal crayfish (Pacifastacus leniusculus) was also observed (now present at stations T3, T4, and T5), reinforcing the need for targeted monitoring and control actions. Overall, the results support the continuation of the current management model, aligned with the conservation objectives defined in the initial plan and in project POSEUR-03-2215-FC-000096, while emphasizing the importance of habitat conservation to ensure the long-term sustainability of trout populations and aquatic ecosystems.

Proceedings doi: 10.3390/proceedings2026146010

Authors: David J. McKenzie

Introduction: The Atlantic bluefin tuna Thunnus thynnus (ABFT) is a large pelagic apex predator with adaptations for a life of ceaseless swimming during long-distance oceanic migrations. The environmental physiology and energetics of tunas have interested researchers for many decades, but they are notoriously challenging to study because they are so difficult to keep in captivity. Adult ABFT are, however, now fattened in cages at various sites in the Mediterranean, while juveniles are reared from hatching every year at the Unique Scientific and Technological Infrastructure for ABFT aquaculture (ICAR-IEO), near Cartagena in Spain. These facilities provide access to animals, but the fish remain very problematic to study because of their highly active but physiologically delicate nature and, for adults, their very large sizes. Objective: To study the in vivo physiology and behaviour of ABFT. Methodology: We used heart rate biologging and high residency acoustic tracking to follow cardiac and swimming activity over a year in n = 24 adult ABFT (mass range 25 to 200 kg) held in a cage off the coast of Malta (Malta Fish Farming). We then performed swim tunnel respirometry on young of the year juveniles (500g) at ICRA-IEO, but subsequently took a ‘hands-off’ approach, using video analyses and group respirometry on free-swimming animals. Results: The descriptive approach on the caged adults provided understanding of how seasonal water temperatures (15 to 28 °C) affect tuna physiology and behaviour. The swimming respirometry on juveniles revealed that their performance was constrained by confinement in the tunnel, compared to when they were swimming at their spontaneous preferred speed in their rearing tank. Video analyses provided insights into the effects of size (25 to 200 cm bodylength) on spontaneous swimming speeds and coupled with tank respirometry, revealed how progressive hypoxia affects the metabolic rate and schooling behaviour of juveniles. Conclusions: These opportunistic and disparate pieces of information are nonetheless valuable for such a fascinating but data-deficient species, and can be useful in mechanistic models for management of an extremely valuable fishery in a context of global change.

Proceedings doi: 10.3390/proceedings2026146008

Authors: Rafael Gaio Kulzer Claúdia Moreira Margarida Hermida Aurélia Saraiva Alberto Teodorico Correia

Introduction: Fish stock identification and delineation are fundamental requirements for preventing local depletion and promoting the sustainable exploitation of marine resources. The blackspot seabream, Pagellus bogaraveo, is the most commercially valuable sparid species across the Northeast Atlantic and the Mediterranean Sea. To effectively discriminate fish stocks, researchers increasingly rely on the use of natural tags, which reflect both environmental and genetic influences, providing critical information regarding fish movements and population structure. Objective: To broaden the understanding of P. bogaraveo stock structure, samples originally obtained for a parasite-based discrimination study were used to provide complementary insights through otolith shape and geochemical signatures. Methodology: A subset of 150 individuals (30 per location) collected across five Portuguese locations (Portugal mainland: Matosinhos, Figueira da Foz, and Sagres; and Archipelagos: Azores and Madeira) was selected for otolith analyses. Otolith contour phenotypic variation was quantified through Elliptical Fourier Descriptors (EFDs) and Shape Indices (SIs), while elemental signatures (element: Ca) were analyzed using solution-based inductively coupled plasma mass spectrometry (SB-ICP-MS). Statistical analyses involved both univariate (one-way ANOVA, followed by Tukey tests, if needed) and multivariate approaches (MANOVA and LDFA), considering both individual and combined datasets. Results: EFDs + SIs yielded the lowest discriminatory power, with an overall reclassification accuracy of 38%. In contrast, Ca signatures provided the highest discrimination at 79%. The combination of both markers resulted in a slightly lower overall accuracy of 75%, likely due to the higher variance associated with the morphological data. Conclusions: In agreement with the previous parasite assessment, these otolith-based approaches confirm that the Macaronesian archipelagos consist of distinct stocks, separate from the Portuguese continental shelf. Furthermore, significant differences in otolith geochemical signatures between Sagres and Figueira da Foz point to a further subdivision of stocks. These findings are consistent with recent genetic data identifying three distinct stocks along the western and southern Iberian Peninsula, reinforcing the need for localized management of P. bogaraveo populations to ensure long-term fishery sustainability.

Proceedings doi: 10.3390/proceedings2026146006

Authors: João Carlos Almeida Ana Rita Lopes Laura Ribeiro Pedro Pousão-Ferreira Ana Margarida Faria

Increasing ocean temperatures are expected to increase the energy needs of marine organisms, therefore increasing food demand to sustain their metabolism. However, food is limited in the aquatic environment and reduced availability may be intensified by the advance of climate change. Despite the importance of these interacting factors, few studies have explored their combined effects, particularly in early stages of the fish. To address this gap, we investigated how increased temperatures and reduced food availability influence agonistic behaviors, risk-taking, exploratory activity, social preference, and shoal structure in the early stages of Sparus aurata (55 dph). Fish were exposed for two weeks to a cross-experimental design involving two temperature conditions (24 °C and 28 °C) and two levels of food availability (9% and 4.5% of body weight). Our findings revealed that temperature and food restriction significantly reduced aggressiveness. Fish subjected to low food availability, regardless of temperature, exhibited bolder behavior, took greater risks, and engaged in more exploration. Higher temperatures independently increased exploratory activity but did not affect risk-taking. Fish from the four treatment conditions demonstrated a preference to associate with shoals. However, under food restriction, fish were more likely to abandon their shoals, and the low food availability in the high temperature treatment led to looser shoal formations. Overall, our results suggest that food availability has a higher impact than temperature. Fish on low food availability reduced energy expenditure on aggressive behaviors, but engaged in riskier behaviors and increased exploration, probably in an effort to locate food resources.

Proceedings doi: 10.3390/proceedings2026146009

Authors: Francisco Baldó Miguel Coján Ignacio Ruiz-Jarabo

Introduction: Elasmobranchs are key components of marine ecosystems but are particularly vulnerable to fishing pressure due to their life-history traits, including slow growth, late maturity, and low fecundity. The Gulf of Cádiz supports a diverse assemblage of coastal and deep-water elasmobranch species, many of which are subject to incidental capture in demersal fisheries. Reliable fishery-independent information on their distribution, relative abundance, and biomass is essential to assess population status and to inform ecosystem-based fisheries management in the northeastern Atlantic. This study aims to provide an updated overview of the composition, relative abundance, biomass, and occurrence of elasmobranch species in the Gulf of Cádiz, contributing baseline information for monitoring and conservation purposes. Methodology: Data were obtained from the ARSA bottom trawl survey carried out in March 2026 using a stratified random sampling design by depth. A total of 45 valid hauls were performed. Results: A total of 29 elasmobranch species belonging to Rajiformes, Carcharhiniformes, Squaliformes, Myliobatiformes, Hexanchiformes, and Torpediniformes were identified. Small demersal sharks and skates dominated the assemblage. Scyliorhinus canicula was the most frequent and abundant species, occurring in 37 hauls and showing the highest mean abundance and biomass. Other recurrent taxa included Torpedo marmorata, Etmopterus spinax, Leucoraja naevus, and Raja clavata. Several species of conservation concern, such as Rostroraja alba, Centrophorus uyato, and Galeorhinus galeus, were recorded at low frequencies and abundances, highlighting their rarity in survey catches. The assemblage reflected a clear dominance of shelf and upper-slope species with occasional captures of deep-water taxa. Conclusions: The ARSA survey provides a valuable snapshot of the current elasmobranch community in the Gulf of Cádiz, confirming the prevalence of small-bodied, benthic species and the low occurrence of large or vulnerable taxa. These results underscore the importance of continued standardized surveys to detect temporal trends and support management strategies aimed at the conservation of elasmobranch diversity in the gulf.

Proceedings doi: 10.3390/proceedings2026146012

Authors: Fernando Cobo Rufino Vieira-Lanero Sandra Barca Pedro Domínguez-García Miguel Cobo-Golpe Gabriela Castro Isaac Rodríguez

Emerging contaminants constitute a growing pressure on river ecosystems due to their persistence, chemical diversity, and ecotoxicological effects. The objective of this study was to analyze the presence of these compounds in muscle tissue across a range of aquatic species, including benthic fish (Gobio lozanoi, Cobitis sp.), nektonic species (Salmo trutta, Lepomis gibbosus), diadromous species (Anguilla anguilla, Petromyzon marinus, in the larval stage), generalist species (Pseudochondrostoma duriense), and crustaceans (Procambarus clarkii). Concentrations were determined using LC-MS/MS, grouping the compounds into different chemical families (e.g., pharmaceuticals, personal care products, industrial compounds, and other emerging contaminants). The results showed significant differences both among species and among compound families. At the interspecific level, Petromyzon marinus (larvae) exhibited the highest total concentrations, followed by Salmo trutta and benthic species such as Gobio lozanoi and Cobitis sp. Intermediate values were observed in Pseudochondrostoma duriense and Lepomis gibbosus, while Anguilla anguilla showed moderate levels. Procambarus clarkii displayed notable accumulation, especially of sediment-associated compounds. Analysis by compound families revealed distinct patterns: pharmaceutical and personal care compounds showed a relatively homogeneous distribution among species, whereas more hydrophobic and industrial compounds tended to accumulate in species with higher lipid content or greater benthic exposure. In particular, benthic species (lamprey larvae, gudgeon, spined loach, and crayfish) showed higher accumulation of sediment-associated compounds, confirming their role as contaminant reservoirs. Lamprey larvae, which exhibit filter-feeding behavior and remain buried in fine sediments for several years, showed high accumulation of multiple contaminant families, highlighting the importance of this life stage as an indicator of environmental contamination. The results demonstrate the coexistence of different accumulation mechanisms: (i) direct exposure to sediment, (ii) trophic biomagnification, and (iii) accumulation linked to the physicochemical properties of the compounds. This combined approach by species and contaminant families allows for a more comprehensive assessment of the ecological status of the system. Finally, the relevance of including multiple taxonomic groups and life cycle stages in monitoring programs is emphasized, especially in vulnerable species such as Petromyzon marinus.

Proceedings doi: 10.3390/proceedings2026146004

Authors: José María Valle-Artaza Enrique Valverde Verónica Maneiro Elias Prieto Ángel Fernández-González Alejandro González-Ibáñez Pedro García-Rovés

Introduction: The sea lamprey (Petromyzon marinus) is an anadromous jawless fish that migrates between marine and freshwater environments, spawning once in rivers before dying. It is distributed along both coasts of the North Atlantic. In Asturias (northern Spain), P. marinus is classified as Vulnerable, and a conservation plan is currently under development. In the present study, Critical Conservation Areas (CCAs) are defined as river reaches requiring urgent protection due to their high ecological value for the species. Objective: This study aimed to identify key reproductive and larval habitats (spawning grounds and silt–sand banks) to support the designation of CCAs for the conservation of the sea lamprey in Asturias. Methodology: Fieldwork was conducted in the main salmonid rivers of Asturias (Deva, Nalón, Narcea, Navia, Eo, and Sella basins). During spring 2025 and 2026, habitats were characterized and spawning sites identified using transects. In autumn 2025, larvae were sampled by electrofishing within defined areas (10–30 m2), measured and weighed, and densities were extrapolated using an inverse distance weighting (IDW) model. Basin use and critical areas were assessed based on species distribution and habitat quality. Results: A total of 1886 larvae were recorded across 27 river sections, of which 1366 were measured. Sea lamprey was present in 74.1% of sections, whereas brook lamprey (Lampetra planeri) was detected only in the Deva basin. Mean larval size was 9.5 ± 3.7 cm and 2.3 ± 2.19 g, with marked spatial variability. The highest larval densities occurred in the Eo (21.5 ind/m2) and Narcea rivers (15.1 ind/m2). Additionally, 94 spawning records were identified, and 65% of the 83 assessed sections were classified as good or very good habitat. Conclusions: A total of 31 CCAs (~300 km) were proposed, including 97 km classified as “of interest”, 21 km as “important”, and 180 km as “highly important”. Habitat use was greatest in sinuous middle river reaches with riffles, pools, and fine sediment deposits. Transversal barriers, dredging, and channel simplification were identified as the main drivers of habitat loss. These findings provide a robust scientific basis for conservation planning and management of the species in Asturias.

Proceedings doi: 10.3390/proceedings2026146018

Authors: Diego Deville Kentaro Kawai Tetsuya Umino Minoru Ikeda

The genus Sebastes comprises around 110 species of marine fish. In Japan, the Sebastes inermis complex includes three sympatric species (S. cheni, S. inermis, and S. ventricosus), and morphotypes that cannot be assigned to any of these three species. We focused on two morphotypes: (1) the ‘big red’, which is predominantly found in the Kii and Izu peninsulas and are traditionally believed to be large, older specimens of S. inermis; and (2) the ‘red white’, which is found in the Seto Inland Sea and Kagoshima and includes putative hybrids of S. cheni and S. inermis. We assessed the biological identity of both morphotypes by comparing their morphological and genetic variations with those of the three species. The meristic traits of both morphotypes overlapped with those of the three species. The ‘big red’ morphotype showed significant differences in body proportions and otolith structure, whereas the ‘red white’ morphotype differed mainly in otolith features. Phylogenetic analyses of mitochondrial and nuclear genes did not separate these morphotypes into distinct lineages. However, the ‘big red’ morphotype exhibited unique mutations at the rhodopsin gene. Analyses of microsatellite loci indicated that the divergence of both morphotypes is as large as the divergence observed between sister species within the genus. Phylogenetic analyses of genomic data placed the ‘big red’ morphotype in a basal position in relation to the three species and supported the separation of the ‘red white’ morphotype from S. cheni and S. inermis. Genomic scan analyses comparing the ‘big red’ and ‘red white’ morphotypes with S. inermis and S. cheni, respectively, indicate that genes involved in fertilization, egg hatching, immunity, and thermal resilience are under divergent selection. Overall, the results suggest that both morphotypes could represent previously undescribed cryptic species, warranting further investigation to confirm their status as independent taxa.

Proceedings doi: 10.3390/proceedings2026146013

Authors: Miguel Vieira de Melo Neto Eduardo Bessa Pereira da Silva Marcos Alexandre Bolson Ézio Sargentini Júnior Luiz Fabrício Zara

Introduction: The entry and accumulation of fish inside the suction tubes of hydroelectric power plants can pose risks to these animals. To protect ichthyofauna, repulsion systems employing diverse methodologies have been developed. Objective: The main objective of this study was to investigate the dissuasive effectiveness of a bubble and light barrier on ichthyofauna. Methodology: The experiment consisted of video recording in three stages, performed in triplicate: before activating the barrier, while the barrier was active, and after deactivating it. The movement of five juvenile Amazonian species (Cichlasoma amazonarum, Dianema urostriatum, Pimelodus blochii, Brycon spp., and Colossoma macropomum) was analyzed across the three stages by counting individuals in specific sectors every 15 s. A total of 30 specimens of each species were used, with 10 individuals allocated to each aquarium. Results: Barrier activation induced repulsion in Pimelodus blochii, Brycon spp., and Colossoma macropomum, but attraction in Cichlasoma amazonarum and Dianema urostriatum. The study reveals that the tested species respond dissimilarly to stimuli from the behavioral barrier. Conclusions: These findings address a research gap regarding native species′ responses to behavioral barriers. They underscore the importance of understanding regional ichthyofauna behavior for designing optimized bubble and light barrier systems to enhance method efficacy. The observed effectiveness highlights the potential of this robust, low-cost technology for ichthyofauna protection in hydroelectric plants.

Proceedings doi: 10.3390/proceedings2026135005

Authors: Kjell Hausken

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Proceedings doi: 10.3390/proceedings2026146005

Authors: Diogo Dias Rui Rivaes Diogo Ribeiro Sofia Nogueira Miguel Rodrigues Beatriz Castro Maria Filomena Magalhães Martin Čech Filipe Ribeiro

Biological invasions and freshwater biodiversity loss are two of the most pressing global conservation challenges yet their interaction during the earliest stages of invasion remains poorly understood. Iberian freshwaters rank among Europe’s most biodiverse ecosystems, harbouring a remarkable assemblage of endemic fish species. This irreplaceable heritage is increasingly threatened by non-native piscivorous predators, to which endemic species often lack innate antipredator responses. The invasive European perch (Perca fluviatilis) was first detected in the Meimoa reservoir, within the Malcata Natural Reserve (Central Portugal), in 2023, and has since expanded exponentially in abundance while dispersing into adjacent stream networks. This emerging invasion provided a unique opportunity to assess the predation impacts of a novel piscivorous predator during the early stages of establishment and dispersion, across both lentic and lotic habitats. From 2022 to 2025, European perch were sampled in the invaded reservoir using gillnetting and in connected streams with electrofishing. Diet was assessed through stomach content analysis, and prey composition was analyzed in relation to site, season, year and ontogeny. European perch exhibited a clear ontogenetic diet shift as expected, from zooplankton and invertebrates to crayfish and fish, with minor variation in prey composition between systems. In the Meimoa reservoir, body size was the strongest driver of diet composition (PERMANOVA: R2 = 0.134, p < 0.001), with 50% of the stomachs from individuals above 35 cm containing fish, with the Iberian nase, Pseudochondrostoma polylepis, being the dominant prey. Diet composition remained stable across years (R2 = 0.007; p = 0.188), despite a 74% decline in nase catch per unit effort (CPUE) between 2022 and 2025. In streams, despite the absence of large perch, piscivory was recorded earlier and encompassing a broader range of native taxa. The sustained predation pressure on P. polylepis, a formerly dominant and culturally significant species, despite its steep population decline, suggests that European perch holds the potential to locally deplete native fish stocks. The advance of this predator into lotic habitats demands urgent conservation action, as it may critically threaten the long-term persistence of one of Portugal’s most vulnerable freshwater taxonomic groups.

Proceedings doi: 10.3390/proceedings2026146019

Authors: Fabrício de Lima Freitas Natan Silva Pereira Patrícia Barros Pinheiro Rodolfo Miguel Silva Ana Méndez Vicente Jorge Pisonero Castro Alberto Teodorico Correia

The South American silver croaker, Plagioscion squamosissimus, holds significant importance for the artisanal fisheries operating in the sub-middle and lower courses of the São Francisco River, located in northeastern Brazil. Its complex horizontal movement patterns and habitat-use preferences are not fully understood in the waters of hydroelectric dam reservoirs, raising important questions for the rational and sustainable management of this species. This study aimed to identify the habitat use of P. squamosissimus individuals captured in three fishers’ associations (Olho D’água do Casado, Petrolândia and Rodelas). Individuals were collected between September 2023 and March 2024. A selection of 25 individuals per location from the same age group (+2 years) was used, following annual age estimation based on existing growth curves. Element-to-calcium (element/Ca) ratios in the otolith cores and edges were determined using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). The data were analyzed using univariate and multivariate statistics to assess the degree of separation between individuals in relation to natal origin (otolith cores) and time of capture (otolith edges) from the three sampling sites. Significant differences in element/Ca ratios between core and edges of the otolith were observed for Ba/Ca, Mg/Ca, Mn/Ca and Sr/Ca ratios. These results indicate an ontogenetic change in the habitat use, in which similarity in core signatures suggests a common natal origin, likely influenced by shared environmental conditions of the individuals investigated in this study.

Proceedings doi: 10.3390/proceedings2026146007

Authors: Filipa Inês Pitacas António Moitinho Rodrigues Manuel Blasco José António López Rocío Casquete María José Benito

Introduction: Fish consumption in Portugal (53.61 kg/year) and Spain (40.68 kg/year) remains the highest in the European Union, highlighting the nutritional and economic relevance of small pelagic species. However, fish composition is highly dynamic and influenced by biological and environmental factors, including reproductive cycle, seasonality, and feeding patterns. European anchovy (Engraulis encrasicolus, EE) and European sardine (Sardina pilchardus, SP) exhibit complementary spawning periods, summer and winter breeders, respectively, making them ideal models to study seasonal nutritional variability. A systematic evaluation of their proximate composition is essential not only for quality control but also to support sustainable fisheries management and nutritional recommendations. Objective: This study aimed to comparatively assess the seasonal variation in proximate composition of EE and SP fillets in early autumn and early spring, identifying species-specific nutritional advantages linked to their reproductive cycles. Methodology: Twelve composite samples (six per season) were analysed, each comprising multiple specimens of the same species (EE or SP). Standard proximate analyses were performed to determine moisture, ash, protein, and lipid content, and energy values were calculated. Statistical comparisons were conducted using SPSS (Version 21) to evaluate seasonal and interspecific differences. Results: Sardines showed higher ash, lipid, and energy values, whereas anchovies exhibited higher protein overall. Marked seasonal differences (p < 0.05) were observed: sardine (SP)—autumn: higher lipid (10.00 g/100 g) and energy (176.22 kcal/100 g); spring: higher protein (21.69 g/100 g) and ash (1.96 g/100 g); and anchovy (EE)—spring: higher protein (23.18 g/100 g), lipid (2.44 g/100 g), and energy (117.68 kcal/100 g). Notably, in early spring, anchovies surpassed sardines in protein, lipid, and energy content, highlighting a seasonal inversion of nutritional value between species. Conclusions: Results demonstrate a clear seasonal complementarity in the nutritional value of anchovies and sardines, directly linked to their reproductive cycles. Sardine reaches its peak nutritional quality in autumn, while anchovy becomes nutritionally superior in spring. The alternating pattern suggests that seasonally targeted consumption and fisheries management strategies could optimise both nutritional intake and resource sustainability. These findings provide a strong basis for developing evidence-based recommendations for consumers, industry, and policymakers. Future research should expand this approach by incorporating fatty acid profiles, micronutrients (vitamin D, selenium), and contaminants (e.g., mercury), enabling a more comprehensive evaluation of nutritional quality and food safety.

Proceedings doi: 10.3390/proceedings2026146015

Authors: Beatriz Castro Bernardo Quintella Gil Santos Rita Almeida Diogo Dias Diogo Ribeiro Rui Rivaes Filipe Ribeiro

Introduction: Biological invasions are a major driver of biodiversity loss, particularly in freshwater ecosystems. The Iberian Peninsula, a hotspot of endemic diversity, is increasingly threatened by invasive predatory fish, which may exert higher predatory rates under warmer environmental conditions, disrupting/endangering native fish communities. One such species is the European catfish (Silurus glanis), a large and voracious apex predator. Despite growing research, most telemetry studies have focused on lentic systems, limiting our understanding of its behaviour in lotic environments. Moreover, high-resolution biologging approaches remain largely unexplored. Objective: This study aims to characterize the habitat use and activity patterns of European catfish in a non-native lotic section of the lower Tagus River, and to identify key environmental drivers shaping its predatory behaviour. Methodology: Adult individuals were tagged with radio telemetry transmitters equipped with temperature, pressure (depth), and 3D-accelerometer archival sensors. A preliminary controlled experiment established activity thresholds to classify behaviours. Ten adult fish were then actively tracked over one year, combining spatial data with high-resolution biologging. Habitat use and activity patterns were analyzed across seasonal and circadian scales. Generalized Additive Models (GAMs) were used to assess the effects of environmental variables on activity levels and depth use, while Hurdle models were applied to identify the environmental drivers influencing the occurrence and frequency of burst activity events (predatory behaviour proxies). Results: Fish displayed strong site fidelity, frequently using structured habitats near riverbanks. European catfish also showed clear seasonal and circadian patterns in habitat use and activity, occupying deeper habitats in winter and shallower areas in warmer seasons. Activity occurred year-round, increasing in spring and summer and peaking at dusk, being influenced by temperature, river flow, season, and time of day. Burst activity occurred more often in spring and at dusk. Conclusions: This study unveils insights on European catfish behaviour in invaded lotic systems, highlighting consistent patterns linked to environmental conditions. These findings can support more targeted and effective management strategies for controlling this invasive species.

Proceedings doi: 10.3390/proceedings2026146011

Authors: Gonçalo Duarte Daniel Mameri Pedro Segurado José Maria Santos Rui Figueira Maria Teresa Ferreira Paulo Branco

Introduction: Fish species represent 25% of all vertebrates across the globe and are one of the most threatened animal groups. At least 40% of the fish fauna occurs in rivers for part of their life cycle. European rivers are home to more than 600 fish species, while also being some of the most impaired and altered ecosystems. Objective: The objective was to assess the vulnerability of freshwater fish communities in European river basins. Methodology: Using RivTool and the CCM2 database, we developed the River Restoration Units (R2Us), a set of spatial units that takes into account river network functioning and allows a higher spatial discretisation than river basins. We developed RivFish, a database about the presence of native freshwater-dependent fish in 1556 Europeans river basins. For this, we collected data from 77 references and validated synonyms and scientific names for 667 species. We used the latest International Union for Conservation of Nature (IUCN) Red List assessment to define species distributions in European rivers. After intersecting with the R2U layer, we curated and validated species names and spatial occurrence using RivFish. To map the vulnerability of freshwater fish communities, we used the Habitats Directive (HD) and the IUCN datasets. These consider a distinct number of species and assess conservation status differently: the HD evaluated 165 species, while the IUCN evaluated 516 species. The HD data allowed calculating the composite indicator of Conservation Status, whereas the IUCN data enabled calculating the vulnerability index. Results: Both ana-lyses show higher richness in central Europe, particularly in the Danube basin. Spatially, both highlight southern Europe as the area where fish communities have the highest vulnerability. However, the HD analysis also indicates the Danube and the western Atlantic basins as having high vulnerability. The IUCN analysis shows the Anatolian and Mediterranean biogeographical regions as those with the highest vulnerability values. Conclusions: Southern Europe’s higher vulnerability is likely associated with restricted distribution ranges and high levels of endemicity in Mediterranean fish communities. Overall, these findings improve current knowledge and show that input data may be key to effort allocation towards the management and conservation of European freshwater fish communities.

Proceedings doi: 10.3390/proceedings2026146003

Authors: Rui Rivaes Christos Gkenas Diogo Dias Beatriz Castro Mafalda Moncada Diogo Ribeiro Filomena Magalhães Filipe Ribeiro

Introduction: The most common method for controlling invasive fishes is mechanical removal, although it is time-consuming and operationally demanding. In Portugal, commercial inland fisheries are permitted, but the extent to which they could represent a complementary tool for invasive species control remains unknown. Objective: We compared fish assemblages in two sections of a branch of the Cedillo Reservoir where commercial fishing is allowed (i.e., downstream the Lentiscais bridge) and where it is prohibited under the regulations of the International Tagus Natural Park (i.e., upstream). Methodology: Fish were sampled in 2023 and 2024, using a total of 116 gillnets: 72 downstream and 44 upstream. The proportion of blank nets between sections was compared using Fisher’s exact test. Variations in community composition were assessed using NMDS and PERMANOVA, while homogeneity of multivariate dispersion was evaluated with PERMDISP. Total CPUE was compared between sections using Mann–Whitney tests. At the species level, CPUE were assessed using permutation-based Mann–Whitney U tests adjusted for multiple comparisons using the FDR procedure. The direction and magnitude of between-section differences were quantified using the rank-biserial correlation, and 95% confidence intervals were estimated by section-stratified bootstrap resampling. Results: In total, 20 gillnets yielded no fish, and there was no significant difference in their proportions between sections. Total CPUE per gillnet was significantly higher upstream than in the commercially fished section. Fish assemblage composition differed significantly between sections, and there were no dissimilarities in multivariate dispersion, indicating a genuine, although partial, separation between assemblages. The species contributing most to the dissimilarity between the two sections were Silurus glanis, Cyprinus carpio, Sander lucioperca, and Luciobarbus bocagei, which are also among the main target species for national inland commercial fisheries. Among these species, L. bocagei and S. glanis showed significantly lower CPUE in the commercially fished section, while S. lucioperca showed higher CPUE. Variations in C. carpio CPUE were barely significant. Conclusions: These results suggest that commercial fishing may at least partially influence fish catches and assemblage structure in this reservoir branch. Future studies should partition the influence of commercial fishing from other drivers of assemblage variation to further evaluate whether it may represent a complementary tool for managing fish invasions under specific management strategies.

Proceedings doi: 10.3390/proceedings2026146002

Authors: Christos Gkenas Vera Sequeira Diogo Ribeiro João Gago Diogo Dias Chandani R. Verma Pradeep Kumkar Filipe Ribeiro

Introduction: The European catfish (Silurus glanis) has expanded rapidly across Europe, significantly impacting native freshwater biodiversity. Despite its well-documented ecological and economic effects as a top predator, reproductive biology data from non-native populations remain scarce, limiting the development of effective management strategies. Objective: This study examines key reproductive traits, sex ratio, size at first maturity, spawning period, fecundity, and oocyte diameter, of an invasive European catfish population in the Lower Tagus River (LTR), Portugal, approximately 15 years after its establishment. Methodology: A total of 674 individuals were collected monthly from January 2022 to November 2023 using electrofishing, gill nets, baited hook-lines, and catches from professional fishermen. Sex and reproductive stage were assessed via gonadal analysis. Size at first maturity was estimated using logistic regression. Fecundity was determined by the gravimetric method, and oocyte stage and diameter were assessed histologically. The gonadosomatic index (GSI) was used to characterise the reproductive cycle. Results: The sex ratio was significantly female-biased (1.4:1). Size at first maturity (TL50) was 72.9 cm TL for females and 68.8 cm TL for males. The spawning season extended from February to June, coinciding with water temperatures of 11–23 °C, with the highest GSI values reported to date for this species (GSI max = 22.5%). Histological analysis confirmed asynchronous oocyte development. Absolute fecundity ranged from 8364 to 319,000 oocytes per female and was positively correlated with total length and body weight. Mean mature oocyte diameter ranged from 1.50 to 3.21 mm. Conclusions: The European catfish in the LTR exhibits high reproductive plasticity, early maturity, a prolonged spawning season, and elevated fecundity, likely facilitated by warm water temperatures and abundant prey resources. Crucially, these parameters reveal earlier maturation and greater reproductive investment relative to native populations, demonstrating an extreme phenotypic plasticity characteristic of successful invasions in southern European aquatic ecosystems. These findings provide essential biological parameters for targeted management, including selective removal of large females, intensified fishing effort during the spawning season, and population monitoring to prevent compensatory reproductive responses.

Proceedings doi: 10.3390/proceedings2026146001

Authors: Sofía Tíscar-Pearce Ilaria Meo Lourdes Encina Amadora Rodríguez-Ruiz Carlos Granado-Lorencio Juan Ramón Cid-Quintero Carlos Orduna

Introduction: Sediment flushing is widely used to recover storage capacity and maintain outlet functionality in Mediterranean reservoirs, but it can also generate short downstream pulses of suspended sediment, oxygen depletion, and ammonia that may threaten fish and fish habitats. Despite this, operation-specific environmental criteria explicitly oriented to reducing acute fish risk during flushing remain poorly defined. Objective: This study aimed to develop and validate a practical operational protocol for sediment flushing in southern Spain, with emphasis on reducing acute downstream risk to fish through field-applicable thresholds, decision rules, and stop criteria. We also evaluated whether water density could serve as a rapid surrogate for total suspended matter (TSM) during operations. Methodology: The protocol was applied to 14 flushing events conducted at seven reservoirs and weirs in Andalusia, southern Spain. Monitoring included upstream and downstream stations, pre-operation baseline surveys, 15-minute measurements during flushing, and post-operation recovery checks. Operational control was based on pre-alert and alert thresholds for dissolved oxygen, ammonium/ammonia, conductivity, suspended matter, and a density-based surrogate for TSM. Protocol validation considered operational safety during flushing, the relationship between field density and laboratory-measured TSM, and before–after multivariate changes in downstream environmental conditions. Results: Threshold exceedances occurred in 5 of the 14 events, comprising 4 pre-alerts and 1 alert. Pre-alerts were mainly driven by ammonium/ammonia or dissolved oxygen, and exceedance durations were generally short (30–120 min). The only alert-level event combined severe oxygen depletion with high sediment concentrations and triggered suspension of the operation, showing the usefulness of the stop rule. Density was significantly related to laboratory TSM in all reservoirs retained for calibration (R2 = 0.365–0.934), supporting its use as a rapid field proxy when calibrated at the reservoir scale. Before–after multivariate analysis detected no consistent overall downstream shift, although event-level responses were heterogeneous. Conclusions: The protocol proved operationally feasible as a science-based framework for managing sediment flushing while reducing acute risk to downstream fish in Mediterranean reservoirs. Its combination of fish-relevant thresholds, real-time monitoring, site-specific density calibration, and explicit stop rules can support safer operations, improve transparency, and strengthen environmental permitting.

Proceedings doi: 10.3390/proceedings2026143016

Authors: Kim Tilbe Gustavo Ybazeta

Canada has the highest incidence of IBD in the Western world [...]

Proceedings doi: 10.3390/proceedings2026143014

Authors: Sathish Gopalakrishnan Lacey Pitre Guy Desmarais Geordie Linford Abhenil Mittal Jeffrey Emack Jordan Herst Prashant Jani

Introduction: [...]

Proceedings doi: 10.3390/proceedings2026143015

Authors: Meagan Noble Armin Farahvash Azadeh Mofid

Purpose: Diabetes prevalence in Northwestern Ontario (NWO) exceeds the national average, with disproportionately high rates of diabetic ketoacidosis (DKA) and hyperosmolar hyperglycemic state (HHS) [...]

Proceedings doi: 10.3390/proceedings2026142009

Authors: Christoforos Ar. Pasialakos

This paper examines the transformation of traditional aircraft maintenance into an AI-driven, digitized process through the evolution of the Onboard Maintenance System (OMS). It conceptualizes the OMS as an “airborne e-hangar,” where embedded artificial intelligence functions operate as virtual engineering teams performing continuous monitoring, diagnostics, and predictive maintenance during flight. Using the literature review synthesis of aviation regulations, technical manuals, and industry practices, the study outlines how OMS integrates subsystems, such as condition monitoring, central maintenance, and electronic logbooks, to enable real-time data processing and fault isolation. Findings highlight that AI-enhanced OMS improves maintenance efficiency, reduces human error, and supports proactive decision-making by converting operational data into actionable insights. The system facilitates seamless data exchange between aircraft and ground operations, enhancing troubleshooting, maintenance planning, and airworthiness compliance. Furthermore, the continuous feedback loop among manufacturers, maintenance organizations, and regulatory authorities contributes to improved aircraft reliability and design optimization. The study underscores the role of AI in minimizing downtime, optimizing maintenance schedules, and enhancing flight safety while maintaining human oversight through advanced interfaces. The originality lies in framing OMS as a fully digitized, intelligent maintenance ecosystem that redefines aircraft maintenance practices and supports safer, more efficient aviation operations.

Proceedings doi: 10.3390/proceedings2026143013

Authors: Florence Morriello Christopher Rosso Matteo Barbosa Meghan Forestell Liam Hopkins

Background and Purpose: Timely hospital discharge is essential to delivering high-quality, patient-centered care and optimizing patient outcomes [...]

Proceedings doi: 10.3390/proceedings2026143012

Authors: Minghan Shi Birubi Biman Yoko Schreiber

Background: Pulmonary blastomycosis is a lung infection caused by thermally dimorphic fungi Blastomyces spp [...]

Proceedings doi: 10.3390/proceedings2026140004

Authors: Jorge Alberto Romero-Hidalgo Ricardo Alberto Rodríguez-Ojeda Paula Concepción Isiordia-Lachica Ricardo Alberto Rodríguez-Carvajal

Agricultural public policy analysis in Mexico is hampered by data fragmentation across 32 decentralized state agencies. This study presents the Mexican Agricultural Policy Observatory (MAPO), a digital governance tool developed using R-Shiny to centralize and visualize policy information. Through a systematic audit and functional classification adapted from World Bank frameworks, 429 were analyzed. Results indicate a significant concentration in financing (42%) and a critical gap in commercialization support. MAPO enhances transparency and enables evidence-based policymaking by cross-referencing policy data with production metrics, facilitating the identification of regional priorities and strategic opportunities for integrated agricultural development.

Proceedings doi: 10.3390/proceedings2026142008

Authors: Sapheya Aftimos Randa Diab-Bahman

Employees are often encouraged to use artificial intelligence (AI) in the workplace, and industry experts tend to promote the idea that AI is here to stay. Extravagant events are consistently held to showcase the magic of AI, yet companies seem to have limited policies and mixed signals concerning AI’s adoption. This is creating a conflicting narrative, as the practical applications of such evolving technologies remain fragmented—particularly, the synergies of the numerous variables at play, which are often explored in isolation or underexplored altogether. As such, this research uses a three-construct approach, which includes ‘Institutional Policies’ and ‘Stakeholder Sentiments’, to explore their individual and collective implications on ‘AI Usage’ in Kuwait from a multi-stakeholder point of view. This is the first research to use a triple-lens framework, stemming from Institutional Theory, Technology Acceptance Model, and Human Capital Theory, to argue that AI usage cannot be assessed from one perspective due to its subjectivity. The methodology includes a quantitative assessment administered to 153 participants (n = 153) using a closed survey. The findings confirm that higher positive views of AI usage are connected to higher Stakeholder Sentiments as well as ‘Institutional Policies’. Also, a moderate relationship was found between ‘Stakeholder Sentiments’ and ‘Institutional Policies’, meaning that better policies are connected to better stakeholder sentiments. The research contributes to the broader literature on AI usage from a practical perspective with a multi-lens framework which takes several constructs into consideration collectively rather than in isolation.

Proceedings doi: 10.3390/proceedings2026143011

Authors: Akos Kazinczi Minghan Shi Azadeh Mofid

Background: Hospital readmission rates for chronic obstructive pulmonary disease (COPD) secondary to exacerbation are associated with a significant risk of death in patients and impose a substantial financial burden on healthcare systems globally [...]

Proceedings doi: 10.3390/proceedings2026142007

Authors: Mohamad Atyeh Steven Telford Dana Yamout May Khafash

This study provides an empirical investigation into the impact of corporate sustainability practices on financial performance in Boursa Kuwait over the period 2015 to 2025. While existing literature has largely focused on firm-level analyses of ESG practices, limited attention has been given to their aggregated effect on market-level outcomes, particularly in emerging markets such as Kuwait. Moving beyond these gaps, the research conceptualizes sustainability as a potential systemic determinant of market behavior, examining its influence on the All Share, Main Market, and Premier Market indices. The study evaluates how variations in environmental performance, governance quality, and transparency of sustainability disclosures are transmitted into various market outcomes, including index returns, volatility, and market capitalization. Employing a combination of regression analysis and time-series modeling, the framework captures both short-term fluctuations and long-term structural dynamics, enabling a nuanced understanding of the complex interplay between ESG practices and market performance. Anticipated findings suggest that improvements in governance mechanisms and sustainability disclosure standards are likely to stabilize market dynamics, mitigate volatility, and support consistent index performance in the longer term, while short term expectations are more difficult to speculate upon. Additionally, the adoption of ESG practices is hypothesized exert positive influence on investor confidence and market participation, as it’s considered to reflect a gradual alignment of Kuwait’s capital market with global sustainability norms.

Proceedings doi: 10.3390/proceedings2026143010

Authors: Arshea Amer Evan Sawula Armin Farahvash Azadeh Mofid

Background: Rates of diabetes are increasing globally and there are concerns regarding increased hospital admissions due to diabetic ketoacidosis (DKA), which can lead to poor health outcomes and increased healthcare costs [...]

Proceedings doi: 10.3390/proceedings2026142006

Authors: Rawa Al Wadani Mirna Safi

In a time of pandemic interruptions, work arrangements and flexible work environments are becoming more and more crucial in service firms. While this issue is central to the ethics and effectiveness of human–AI interaction, it has received limited focused attention in both research and practice. As businesses increasingly deploy AI to enhance productivity and efficiency, concerns are emerging about its potential impact on employee well-being resulting specifically in work–life conflict. This study investigates how AI implementation can simultaneously drive performance and contribute to burnout, drawing on an empirical framework. Using a quantitative research design, data will be collected from employees at a university in Kuwait actively integrating AI technologies into their workflows. Guided by the IMPACT model and grounded in the Conservation of Resources (COR) theory and the Social Cognitive Theory (SCT), this study explores how organizational investment in AI influences employees’ experiences of work–life conflict. The findings will highlight AI’s dual role as a productivity enhancer and a potential stressor within a Kuwaiti institution. The study underscores the importance of balanced digital strategies—aligning technological advancement with leadership empathy, robust support systems, and employee well-being initiatives. By contextualizing global research within Kuwait’s evolving digital landscape, this study contributes region-specific insights and practical recommendations for fostering human-centered, sustainable AI integration. Ultimately, it aims to guide organizations in designing AI policies that enhance productivity without compromising employee health, advancing the responsible and ethical management of AI in the workplace.

Proceedings doi: 10.3390/proceedings2026142004

Authors: Meshari A. Al-Ebrahim Sami Asaad Mostafa Abdrabboh Abdalrahman Alajmi Amro A. Nour

Economic diversification across the Gulf region, including Kuwait Vision 2035, positions smart manufacturing as a key enabler of sustainable growth. Yet, industrial datasets in the region are typically small, heterogeneous, and incomplete, limiting the performance and trustworthiness of conventional AI models. This paper introduces a Scalable Random Forest (SRF) framework enhanced with a Decision Path Search (DPS) mechanism to address these challenges through both technical robustness and practical interpretability. The SRF pipeline incorporates leakage-safe preprocessing, mixed-type imputation, and small-data augmentation to improve prediction stability under real industrial constraints, while DPS transforms model internals into actionable operational causal knowledge identifying optimal and avoidance parameter ranges. Case studies, including investment casting, demonstrate that SRF + DPS not only outperforms established baselines such as Random Forest (RF), XGBoost, LightGBM, and CatBoost but also deliver transparent insights that engineers can directly apply to reduce defects and enhance process control. The findings highlight how interpretable AI frameworks can accelerate industrial modernization, strengthen regional manufacturing competitiveness, and support national economic diversification strategies.

Proceedings doi: 10.3390/proceedings2026142005

Authors: Sarah (Sa’arah) Alhouti Alan R. Wagner

This research proposal examines how the use of generative artificial intelligence (AI) in corporate social responsibility (CSR) communication shapes perceptions of authenticity and political–cultural polarization. Although AI is increasingly embedded in marketing and communication functions, CSR represents a uniquely sensitive domain in which sincerity, moral intent, and ethical deliberation are essential for effectiveness. Prior research suggests that AI-generated prosocial messages may influence perceived authenticity, particularly when social or ethical causes are politically charged. Building on this tension, the proposed research advances a three-study program to examine when and why AI-mediated CSR communication becomes polarizing and how such polarization shapes stakeholder perceptions. Study 1 develops a large-scale Instagram-based dataset of firm-generated CSR messages to identify message characteristics and issue domains associated with heightened stakeholder polarization. Study 2 evaluates whether generative AI can function as an ex ante diagnostic tool by forecasting polarization risk based solely on message content prior to publication. Study 3 experimentally compares AI-generated and human-generated CSR messages across low- and high-polarization causes to assess differences in perceived authenticity, trust, and anticipated stakeholder conflict.

Proceedings doi: 10.3390/proceedings2026140003

Authors: Eriona Shtëmbari

Digital transformation is a must to remain competitive in today’s advanced technological environment. This study examines how digitalization influences the performance of SMEs in Albania, focusing on digital adoption, skills, training, and institutional support. Using survey data from SMEs in Tirana, based on the Technology–Organization–Environment (TOE) framework and Dynamic Capability Theory, the study aims to investigate the extent of digital service adoption by these organizations. The findings show a positive association between the degree of digital adoption by SMEs and various performance indicators. However, SMEs mainly adopt digital tools and processes without undertaking a complete digital transformation. Multiple barriers prevent SMEs from adopting digital technologies. Despite the digital training offered to SME employees, there is no correlation between the training and the adoption of these digital technologies. The study makes various contributions to the literature on the digital transformation of SMEs and has implications for policy making in the context of the transition economies.

Proceedings doi: 10.3390/proceedings2026142003

Authors: Zekeriya Emre Erkal Bora Yıldız

While higher education institutions strive for academic excellence, they also bear the responsibility of caring for and ensuring the sustainable well-being of their students. After the COVID-19 pandemic, these institutions have transitioned to hybrid and digital education models and have begun to experience the opportunities and threats of digital learning ecosystems. With the introduction of AI technology, this transformation has taken on a new dimension: while students benefit from the flexibility, instant feedback, and personalized learning offered by AI tools, they have also begun to experience new challenges, including cognitive overload, digital fatigue, and social isolation. In this context, the aim of this research is to assess students’ overall psychological well-being and to provide a support system that promotes sustainable well-being by anticipating potential psychological strain and recommending necessary precautions. Accordingly, the purpose of this study, drawing on Self-Determination Theory and Conservation of Resources Theory, is to examine the direct effects of an AI-enabled student support system on sustainable well-being and academic engagement, as well as its indirect effects through self-efficacy and academic resilience. Data will be collected from undergraduate students from a public university in Istanbul. Data will be analyzed in the R statistical environment. We expect that academic resilience, and self-efficacy will mediate the relationship between an AI-enabled student support system and sustainable well-being. At the end of the study, we propose a conceptual model that can be tested empirically by further research. Managerial and further research directions, as well as limitations, are also discussed.

Proceedings doi: 10.3390/proceedings2026142002

Authors: Rola Mourdaa

The Gulf Cooperation Council (GCC) countries, heavily reliant on oil revenues, have long aimed to diversify their economies to mitigate the volatility of global oil prices and foster sustainable growth. Two countries, Saudi Arabia, representing the biggest economy, and Kuwait, the third biggest economy in the GCC, were chosen based on their promising economic visions, while being considered as the more historically conservative countries. Both countries represent case studies to reflect on the effectiveness of their diversification measures on GDP/capita as one of the main macroeconomic indicators for prosperity. The paper aims to use time series data over the period 2000–2024 for both countries to reflect the diversification efforts on GDP per capita. A straightforward multivariate regression model is employed, utilizing the value-added contributions of the three primary sectors—industry, agriculture, and services—to examine whether recent economic transformations and policy reforms have influenced GDP per capita and to identify in which country reforms exerted the greatest impact. Findings are expected to reflect a bigger impact of diversification aims on GDP/capita in Saudi Arabia due to the pace of reforms that have been implemented. This research shall provide valuable insights for policymakers, highlighting the need to promote policy reforms to foster sustainable economic growth. The outcome of this study will provide hydrocarbon-dependent GCC economies with an updated, replicable methodological framework to support a better formulation of policy and strategy connecting digital transformation and sustainability agendas in line with efforts related to the Saudi Vision 2030 and Kuwait Vision 2035, which shall present a benchmark that can be applicable for the other GCC economies.