Search Results (101)

Oceanic tuna fisheries are a major contributor to the economic health of Pacific Island countries (PICs), with coastal fisheries underpinning the livelihoods of locals, providing food security, significant employment, culture, and human welfare. Livelihood development across various PICs is hindered by the inability to harness the maximum potential of coastal fishery resources, particularly through the lack of identifying targeted development needs. Development of coastal value chains facilitates resilience by reducing local reliance on tuna fisheries and associated vulnerability to tuna industry dynamics to support socio-economic development throughout the PICs while maintaining food security. The aim of this paper is to identify priority opportunities for developing coastal resource value chains in PICs, targeting increased local economic resilience and food security. A methodology developed by the World Bank was used to assist stakeholders and policymakers to coalesce around common strategies for the value chains. Six value chains were identified: beche-de-mer; ornamental black pearls and Trochus shell; fresh fish for the domestic market; reef fish exports; export of live lobsters; and export of aquarium fish products. Porter’s Five Forces framework was used for value chain analysis, and strategic repositioning considerations and areas for investment support within high-priority value chains were identified. Fisheries data collection, community-based sustainable management and aquaculture restocking programmes, habitat restoration, development of the cold chain, air freight logistics for export, and facilitating international market connections and market access were identified for external investment support. Full article

This study assessed the effects of thymol and yeast Saccharomyces cerevisiae on the growth performance, antioxidant capacity and immunological responses and gut immunological transcripts in rainbow trout, Oncorhynchus mykiss. Two hundred and seventy fish (6.62 ± 0.18 g) were distributed in 18 aquaria (15 fish per aquarium) as a 2 × 3 factorial design. The fish were fed on diets containing 0 and 1 × 10⁸ cfu/g of yeast and 0, 250 and 500 mg/kg of thymol for 60 days. The results showed that dietary yeast supplementation led to significantly improved fish weight gain and feed efficiency (p < 0.05). Thymol and yeast supplementation affected the hepatic antioxidant status, leading to lower lipid peroxidation and higher glutathione reserves (p < 0.05). Thymol and yeast supplementation led to significantly lowered plasma aspartate aminotransferase levels (p < 0.05). Dietary yeast supplementation led to significantly elevated plasma and mucus lysozyme, plasma alternative complement, immunoglobulin and mucus alkaline phosphatase levels. In contrast, thymol supplementation led to significantly increased plasma lysozyme and mucus alkaline phosphatase levels (p < 0.05), whereas it had no significant effects on other immunological parameters. The mucus bactericidal activities were improved by dietary yeast but both supplements enhanced the plasma bactericidal activity (p < 0.05). Thymol and yeast supplementation significantly up-regulated the expression of tumor necrosis factor-alpha, interleukin-1 beta, transforming growth factor-beta, beta-defensin and heat shock protein-70 in the hindgut (p < 0.05). In conclusion, dietary yeast supplementation was particularly effective in enhancing fish growth performance and non-specific immunity, while thymol supplementation primarily led to improved antioxidant capacity. Notably, a dietary dose of 250 mg/kg of thymol alone failed to affect the gut transcription as much as 500 mg/kg; however, the co-supplementation of 250 mg/kg of thymol and yeast led to comparable results. Full article

Two Indian Ocean surgeon fish Paracanthurus hepatus individuals were observed near Saint-Raphaël (Provence, France, north-western Mediterranean Sea) in the late summer of 2024 in Posidonia oceanica seagrass and reef habitats. This species is very popular among aquarium hobbyists in Europe, and a growing number of mega-yachts, such as those which moor in the Saint-Raphaël marina, have seawater aquariums on board. Accidental or deliberate release from one such aquarium is the most probable origin of these individuals. The first individual was speared and the second one was no longer sighted after a September storm. Their establishment is unlikely; however, in the future, with the warming of Mediterranean waters and the rapid increase in the number of mega-yachts, this could change. Yacht owners and their staff should be informed of the risk posed by aquarium discharges. Full article

Nitrification plays a crucial role in aquatic ecosystems and in the biofilters used in fish farms. Despite their importance, the role of canonical nitrifiers, comammox bacteria, and archaea has not yet been sufficiently investigated. The aim of this study was to characterize the microbiome of the external canister biofilter in a freshwater fish aquarium, with particular focus on the role of comammox Nitrospira and their competition with other nitrifiers. To achieve this, a comprehensive approach combining metagenome sequencing and co-occurrence network analysis was used to study the interactions between microorganisms in portable biofilter. The fish were subjected to a changing feeding regime that affected the ecological relationships and abundance of different microbial taxa. The results showed the presence of two types of nitrifiers in the biofilter: comammox Nitrospira and ammonia-oxidizing archaea (AOA). Five comammox Nitrospira genomes were reconstructed, with comammox clade B being the most abundant with an average abundance of 7.8 ± 0.4%. In addition, two families of archaea were identified: Nitrosopumilaceae and Nitrososphaeraceae, with an average abundance of 4.3 ± 0.4%. Heterotrophs were also abundant in the bacterial community, particularly in the genera Actinomycetota, Planctomycetota, and Pseudomonadota. Network analysis indicated competitive interactions between comammox and heterotrophs, whereas no competition was observed between comammox and AOA. The predominance of comammox Nitrospira, and AOA over canonical nitrifiers emphasizes their better adaptation to oligotrophic environments. This study highlights the importance of competition within the biofilter microbiome and the role of ecological interaction networks, which can contribute to the optimization of water purification systems in RASs. Full article

Aluminum (Al) can cause endocrine disruption in aquatic animals, but assessments of animal social behavior in neotropical teleost fish species with importance for Brazilian aquaculture have still not been addressed so far, which can further complete this ecotoxicological knowledge. In order to evaluate the social behavior and plasma cortisol concentration of fish exposed to Al, we performed a 1 h acute exposure with Astyanax lacustris couples in three different experimental groups: control in neutral pH (CTL/n group), acid pH (pH/ac group), and aluminum in acid pH (Al/ac group; 2.0 mg L⁻¹). An ethogram of social interactions between males and females and swimming activities were performed. Furthermore, the cortisol plasma concentration was measured by enzyme-linked immunosorbent, and the gonadal maturation stage of the animals was evaluated by histology. Adult and mature females in the CTL/n and pH/ac groups were more aggressive and active than mature males, including several attacks on the male. Moreover, males did not present attack behavior in these groups at any time, but did show submission behavior and constant avoidance of female attacks. In the Al/ac, females did not attack males, couple decreased swimming activity, a repetitive movement toward the aquarium surface, and high mucus production were observed, making the water cloudy. Regarding cortisol plasma concentration, males had higher cortisol plasma concentrations than females in the CTL/n and pH/ac groups, which was not observed in the Al/ac group. Therefore, Al in addition to being described in the literature as an endocrine disruptor, it can be considered as behavioral disrupter in A. lacustris in this important freshwater species cultivated in South America. Full article

Organically modified clinoptilolite (member of the zeolite family of minerals; MinazelPlus^®) feed additive, with an average weight of 30 ± 2 g, was used to prevent mycotoxicosis in Nile tilapia (Oreochromis niloticus) through its supplementation for 42 days to the diet contaminated with multiple mycotoxins: aflatoxin B1 (40 µg/kg), fumonisin B1 and B2 (600 µg/kg), zearalenone (50 µg/kg), and deoxynivalenol (150 µg/kg). The fish were divided randomly into four experimental groups (basal diet control—C; fed 2 g/kg MinazelPlus^®—MZ; fed multiple mycotoxins—MT; and fed a combination of MinazelPlus^® and multiple mycotoxins—MZ + MT). Each group consisted of triplicate aquarium setups, with six fish in each replicate. Sampling was performed in weeks 2, 4, and 6. The lymphocyte count was significantly higher in the MZ group compared with the MT group and the MT + MZ group in week 6. An overall decrease in the neutrophil count was observed in the experimental groups. Histopathological analysis was performed in weeks 2 and 6, revealing significant changes in the liver, intestines, kidney, and spleen of fish from the MT group, while the MT + MZ and MZ groups were similar to the control. The addition of 2 g/kg MinazelPlus^® has the ability to prevent and reduce the adverse effects of chronic exposure to low concentrations of multiple mycotoxins in juvenile Nile tilapia. Full article

This study highlights the potential of aquariums as research platforms for bioacoustic research. Aquariums provide access to a wide variety of fish species, offering unique opportunities to characterize their acoustic features in controlled settings. In particular, we present a preliminary description of the acoustic characteristics of Myripristis jacobus, a soniferous species in the Holocentridae family, within a controlled environment at a zoological facility in the Canary Islands, Spain. Using two HydroMoth 1.0 hydrophones, we recorded vocalizations of the blackbar soldierfish in a glass tank, revealing a pulsed sound type with a peak frequency around 355 Hz (DS 64), offering a more precise characterization than previously available. The vocalizations exhibit two distinct patterns: short sequences with long pulse intervals and fast pulse trains with short inter-pulse intervals. Despite some limitations, this experimental setup highlights the efficacy of cost-effective methodologies in public aquariums for initial bioacoustic research. These findings contribute to the early stages of acoustic characterization of coastal fishes in the western central Atlantic, emphasizing the value of passive acoustic monitoring for ecological assessments and conservation efforts. Moreover, this study opens new avenues for considering the acoustic environment as a crucial factor in the welfare of captive fish, an aspect that has largely been overlooked in aquarium management. Full article

This study aimed to evaluate the effect of dietary orange peel fragments (OPFs) enriched with vitamins C (C) and E (E), as well as zinc (Zn) on the growth performance, hematological profile, immunological parameters, antioxidant capacity, and fillet lipid peroxidation of Nile tilapia subjected to heat/dissolved oxygen-induced stress (HDOIS), transport-induced stress (TIS), and Aeromonas hydrophila infection (BC). A group of 500 male Nile tilapia (2.7 ± 0.03 g) was randomly distributed in twenty-five 250 L aquaria (20 fish/aquarium) and fed diets containing OPFs (6 g kg⁻¹), OPFs/C (6 g kg⁻¹/1.8 g kg⁻¹), OPFs/E (6 g kg⁻¹/0.4 g kg⁻¹), OPFs/Zn (6 g kg⁻¹/0.21 g kg⁻¹), or OPFs/C/E/Zn (6 g kg⁻¹/1.8 g kg⁻¹/0.4 g kg⁻¹/0.21 g kg⁻¹) for 100 days. The diets were formulated to contain 30% crude protein and 17 MJ kg⁻¹ gross energy. After the feeding period, three groups of fish were independently subjected to a different type of stress: HDOIS (34 °C) for two days; TIS for four hours, or BC for 15 days. The hematological profile, antioxidant capacity, and fillet lipid peroxidation were determined before and after all the stress treatments, along with immunological parameters, which were investigated only for the fish subjected to bacterial infection. In summary, the results showed that growth was not affected by the OPFs, nor by the OPFs enriched with C, E, and Zn; bacterial infection determined anemia for the fish fed any of the experimental diets; the OPFs did not prevent lipid peroxidation under TIS and BC; on the other hand, when enriched with C/E/Zn, lipid peroxidation decreased under HDOIS and TIS. In conclusion, the OPFs enriched with C/E/Zn showed a synergistic effect that promoted an increase in antioxidant enzyme activity, a decrease in lipid peroxidation, and the maintenance of the hematological profile under HDOIS and TIS, but they were not able to maintain the health status under BC. Full article

The participation of animals during complementary therapy for humans is a developing area. Dogs and horses are the most frequent partner species in animal-assisted services, but several unconventional species have also been involved, although there is a lack of information about the stress they experience caused by AAS. We conducted a comprehensive literature search, analyzing 135 articles with the purpose of investigating the effects of AAS on unconventional species such as guinea pigs, rabbits, farm animals, alpacas, donkeys, reptiles, aquarium fishes, and dolphins. We found that the relevant articles emphasize investigating the impact of animal-assisted interventions on humans, and they generally report positive outcomes. Limited data is available concerning the potential consequences the interventions may have on the animals. Therefore, it is our conclusion that more extensive studies should be conducted to get adequate information on stress experienced by animals during AAS, such as the measurement of biochemical parameters such as cortisol. Hence, meeting animal welfare considerations in addition to human interests could serve as a basis for the recommended methodology for therapies. Full article

Environmental enrichment can provide captive animals with stimuli that increase physical and mental activity. We investigated the extent to which a novel enrichment item, defined as enrichment that individuals have never experienced prior to the study, engages captive cownose stingrays (Rhinoptera bonasus). We hypothesized that stingray interactions with the enrichment item are associated with the novelty of the enrichment item (i.e., time since presentation of the enrichment item, number of weeks exposed to the enrichment), the presence of food, and the number of human visitors at the stingray exhibit. The novelty of the enrichment item and the presence of food were most strongly associated with stingray interactions with the enrichment item. Although stingrays engaged with the enrichment throughout a 5-week period, interactions decreased as the amount of time the enrichment item remained in the water increased during a 60 min period and interactions decreased as the weeks progressed. Furthermore, stingrays had increased interactions when food was present inside the enrichment item. The number of human visitors had a weaker association with stingray interactions with the enrichment item, but during the food-based trials, there were increased interactions with the enrichment when more visitors were present. Our findings suggest that variation in enrichment routines (to maintain novelty) and variation in an enrichment item’s use of food may help continue engagement with enrichment items. Full article

With the development of smart aquaculture, the demand for accuracy for underwater target detection has increased. However, traditional target detection methods have proven to be inefficient and imprecise due to the complexity of underwater environments and the obfuscation of biological features against the underwater environmental background. To address these issues, we proposed a novel algorithm for underwater multi-target detection based on the YOLOv8 architecture, named SQnet. A Dynamic Snake Convolution Network (DSConvNet) module was introduced for tackling the overlap between target organisms and the underwater environmental background. To reduce computational complexity and parameter overhead while maintaining precision, we employed a lightweight context-guided semantic segmentation network (CGNet) model. Furthermore, the information loss and degradation issues arising from indirect interactions between non-adjacent layers were handled by integrating an Asymptotic Feature Pyramid Network (AFPN) model. Experimental results demonstrate that SQnet achieves an mAP@0.5 of 83.3% and 98.9% on the public datasets URPC2020, Aquarium, and the self-compiled dataset ZytLn, respectively. Additionally, its mAP@0.5–0.95 reaches 49.1%, 85.4%, and 84.6%, respectively, surpassing other classical algorithms such as YOLOv7-tiny, YOLOv5s, and YOLOv3-tiny. Compared to the original YOLOv8 model, SQnet boasts a PARM of 2.25 M and consistent GFLOPs of 6.4 G. This article presents a novel approach for the real-time monitoring of fish using mobile devices, paving the way for the further development of intelligent aquaculture in the domain of fisheries. Full article

In recent decades, interest has been aroused worldwide in the use of silicon in nutrition; however, information on its effect on nutrition and metabolism of fish is limited. The objective of the research was to evaluate the effect of dietary supplementation with organic silicon on the growth performance, blood biochemistry, digestive enzymes, morphohistology and intestinal microbiota and stress resistance in hybrid Tilapia (Oreochromis mossambicus × Oreochromis niloticus). Methodologically, six levels of organic silicon (DOS) [control (0), 10, 20, 30, 40 and 50 mg·kg⁻¹] were used to feed juvenile fish (initial weight 7.51 ± 0.25 g) grown for eight weeks in 18 aquariums (15 fish/aquarium). The results indicated that growth performance showed differences (p < 0.05) for specific growth rate, feed conversion and survival. Triglycerides, cholesterol and glucose, transaminases and digestive enzymes were significantly influenced by DOS levels. The histological study confirmed that the administered diets did not cause damage and induced significant morphological changes in the proximal intestine. The 16S rRNA gene sequencing analysis of the gut microbiota showed a high diversity and richness of OTU/Chao-1, with Fusobacteria, Proteobacteria, Bacteroidetes and Acidobacteria predominating in the DOS treatments compared to the control (p < 0.05). Induction of hypoxia stress after the feeding period showed a significant relative survival rate of 83.33% in fish fed 50 mg·kg⁻¹. It is concluded that the DOS treatments performed better than the control treatment in most of the variables analysed. DOS had no negative effects on the fish. The results showed that up to 50 mg·kg⁻¹ DOS improved digestive, metabolic and growth performance in hybrid Tilapia. Full article

Live fish transportation is crucial for managing aquaculture but can pose health risks to fish due to stressors encountered during transportation. Gamma-aminobutyric acid (GABA) is an inhibitory neurotransmitter that plays a crucial role in the central nervous system and is considered to exhibit anti-stress effects. This study aims to investigate the effects of GABA on the transport water quality, plasma biochemical indices, energy metabolism, and antioxidant capacity of tawny puffer (Takifugu flavidus) under transport stress. Tawny puffer were pretreated by immersing in aquariums containing GABA (final concentrations at 0, 5, 50, and 150 mg/L) seawater for 3 days; then, simulated transport was conducted using oxygen-filled polyethylene bags containing the same concentration of GABA seawater as the pretreatment period. Water samples, plasma, and liver were collected after 0, 6, and 12 h of transport. The results revealed that with the prolongation of transportation time, the control group’s water quality deteriorated, stress-related plasma biochemical indices increased, glycolytic substrate contents decreased, glycolytic enzyme activities and product contents increased, and aerobic metabolic enzyme activities exhibited initial increases followed by declines, ATPase activities decreased, antioxidant enzyme activities decreased, and the lipid peroxidation marker contents increased. It is noteworthy that GABA treatment could avoid water quality deterioration during transportation, inhibit an elevation in stress-related biochemical indicators, regulate energy metabolism, and reduce oxidative damage in tawny puffer, especially at 50 and 150 mg/L concentrations. In summary, GABA treatment can effectively alleviate the transport stress of tawny puffer. Full article

The cownose ray (Rhinoptera bonasus) faces vulnerability primarily due to unregulated fishing, resource overexploitation, and habitat degradation. Consequently, individuals maintained under human care play a pivotal role in species conservation, particularly when their welfare is prioritized. Achieving optimal welfare in aquarium settings relies heavily on effective management practices, notably environmental enrichment. However, research on the efficacy of such techniques for cownose rays remains limited. Thus, this study sought to evaluate the impact of various food enrichment items on the behavior of four individuals at the São Paulo Aquarium in Brazil. The project encompassed three phases: baseline, enrichment, and post-enrichment. Enrichment items, designed to mimic the species’ natural foraging behavior, included an ice block containing food, food hidden in vegetables fixed to structures at the bottom of the tank, a tray with substrate and food, and a perforated plastic container with food inside. Behavioral observations utilized focal sampling with instantaneous recording every minute. Results showed increased foraging activity in the post-enrichment phase, whereas swimming increased and following behaviors decreased during the enrichment phase. Additionally, foraging behaviors predominantly occurred near the aquarium bottom. Overall, findings suggest that enrichment items effectively stimulated natural behaviors in cownose rays and were very attractive to the fish, advocating for their integration into species management protocols to enhance welfare. Full article

Wild-caught fish from coral reefs, one of the most threatened ecosystems on the planet, continue to supply the marine aquarium trade. Despite customs and veterinary checks during imports, comprehensive data on this global industry remain scarce. This study provides consolidated data on the largest import market by value, the European Union (EU): a 24-million-euro annual trade value, detailing the main exporting and importing countries, as well as the species and families of the 26 million specimens imported between 2014 and 2021. A watchlist alert system based on the number of specimens traded, import trends, and vulnerability index according to FishBase and the IUCN Red List conservation status is presented, providing key information on which species should require closer scrutiny by authorities. While the European TRAde Control and Expert System (TRACES) electronically monitors the movement of live animals to respond quickly to biosecurity risks, one-third of marine ornamental fish imported lack species-level information. With minor adjustments, TRACES holds the potential to significantly enhance data granularity and the monitoring of wildlife trade, with marine ornamental fish being an interesting case study to validate this approach. Full article