Fishes

12 pages, 6995 KiB

Open AccessArticle

Matings Between Individuals with Similar Major Histocompatibility Complex (MHC) Improve Offspring Survival in the Rainbow Trout (Oncorhynchus mykiss)

by Cinzia Bergamino, Mattia Tomasoni, Silvia Colussi, Vittoria Montemurro, Ilhan Altinok, Marino Prearo, Charalampos Kotzamanidis, Pier Luigi Acutis, Ana Isabel Vela, Simona Sciuto, Giuseppe Esposito, Donatella Volpatti, Elena Bozzetta, Katia Parati, Lucia Aidos, Lucio Fariano and Benedetto Sicuro

Fishes 2024, 9(11), 436; https://doi.org/10.3390/fishes9110436 (registering DOI) - 27 Oct 2024

Abstract

The major histocompatibility complex (MHC) consists of genes involved in immune response and molecular discrimination between self and non-self. MHC genes are the most polymorphic in vertebrates. The origin and maintenance of polymorphism in MHC genes in populations is still unresolved. Mechanisms such [...] Read more.

The major histocompatibility complex (MHC) consists of genes involved in immune response and molecular discrimination between self and non-self. MHC genes are the most polymorphic in vertebrates. The origin and maintenance of polymorphism in MHC genes in populations is still unresolved. Mechanisms such as sexual selection and heterozygote advantage have been suggested as explanations for this high variability. In this study, a farmed population of rainbow trout (Oncorhynchus mykiss) characterized by the presence of specific MHC class IIB gene haplotypes at a frequency higher (30%) than that expected from random matings was investigated. Therefore, it was hypothesized that disassortative matings occur with an adaptive advantage for females, resulting in improved reproductive performance when mated with individuals with similar MHC haplotypes. Genetic analyses of the breeders were performed to define the MHC haplotypes and to perform specific matings. The effect of mating was evaluated by analyzing the survival rate of the offspring at various stages of incubation until swim-up. The reproductive performance of the offspring derived from specimens with similar haplotypes showed a better survival trend during the first life stages and reduced malformations. The results obtained are in contrast with the heterozygous advantage theory, therefore it was hypothesized, as for other salmonid species, the presence of a positive selection towards locally adapted MHC genes that promotes reproduction between genetically similar individuals. Full article

(This article belongs to the Special Issue Advances in Rainbow Trout)

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15 pages, 8253 KiB

Open AccessArticle

New Insights into Fish Diversity in the Yellow and Bohai Seas Based on Environmental DNA Technology

by Xiaolin Wang, Li Wang, Aiyong Wang and Linlin Zhao

Fishes 2024, 9(11), 435; https://doi.org/10.3390/fishes9110435 (registering DOI) - 26 Oct 2024

Abstract

Marine biodiversity is increasingly threatened by overfishing and marine pollution. A comprehensive understanding of the biodiversity in the Yellow and Bohai Seas is essential for resource conservation. This study conducted a large-scale survey of fishery resources in the Yellow and Bohai Seas to [...] Read more.

Marine biodiversity is increasingly threatened by overfishing and marine pollution. A comprehensive understanding of the biodiversity in the Yellow and Bohai Seas is essential for resource conservation. This study conducted a large-scale survey of fishery resources in the Yellow and Bohai Seas to investigate fish community structure and diversity using eDNA technology. The results showed that 57 and 65 fish species were recorded in spring and summer, respectively, with 46 species identified in both seasons. A total of nine dominant species were identified in spring, mainly belonging to Perciformes, while seven dominant species were identified in summer, primarily from Clupeiformes. In different regions, no significant differences in fish α diversity were observed between spring and summer. However, significant seasonal differences were found in both α and β diversity. At the spatial level, fish species in the Yellow and Bohai Seas occupied similar ecological niches. However, at the temporal level, there are certain differences in the ecological niches of fish communities between seasons. Phylogenetic diversity showed no significant differences at the spatial scale, yet notable seasonal variations were observed at the temporal scale, with spring (661.46) significantly exceeding summer (540.30). The Mantel test indicated that nitrate and salinity were key environmental factors influencing α diversity. RDA analysis revealed that the dominant species in spring were mainly influenced by chlorophyll-a and water temperature, while those in summer were mainly affected by water depth, nitrite, water temperature, and salinity. Full article

(This article belongs to the Special Issue Assessment and Management of Fishery Resources)

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17 pages, 1327 KiB

Open AccessArticle

Development of Low-Resistance Coastal Stow Net Using Numerical Analysis and Model Experiments

by Sua Park, Jihoon Lee, Minseo Park and Daeyeon Cho

Fishes 2024, 9(11), 434; https://doi.org/10.3390/fishes9110434 (registering DOI) - 26 Oct 2024

Abstract

In coastal stow net fishing, the heavy weight of a typical anchor (750–1000 kg) can increase the risk of capsizing the boat and crew member injury during hoisting operations. Thus, to prevent these accidents, a reduction in the anchor weight is required. One [...] Read more.

In coastal stow net fishing, the heavy weight of a typical anchor (750–1000 kg) can increase the risk of capsizing the boat and crew member injury during hoisting operations. Thus, to prevent these accidents, a reduction in the anchor weight is required. One strategy to achieve this is to reduce the resistance force of the fishing gear used, which would allow lighter anchors to be employed. This requires the accurate estimation of the resistance force for various gear designs. Therefore, the resistance force and shape during the operation of two representative types of coastal stow nets currently employed in the Korean coastal stow net fishing industry were investigated using simulations and modeling experiments. The modeled fishing gear was divided into four sections according to the mesh size. Based on the results, the twine thickness was reduced in order to target areas of the gear where the greatest resistance was observed, while the front part of the gear was redesigned to prevent the front of the net from being pushed back into a suboptimal shape. The proposed low-resistance fishing gear has the potential to improve occupational safety in the coastal stow net fishing industry. Full article

(This article belongs to the Special Issue New Technologies for Improving Fisheries and Aquaculture Production and Management)

24 pages, 2961 KiB

Open AccessArticle

Fishes Associated with a Vulnerable Marine Ecosystem Network in the Central Mediterranean Sea

by Angela Carluccio, Francesca Capezzuto, Porzia Maiorano, Letizia Sion and Gianfranco D’Onghia

Fishes 2024, 9(11), 433; https://doi.org/10.3390/fishes9110433 (registering DOI) - 26 Oct 2024

Abstract

In order to collect information on fishes and benthopelagic fauna of a deep-sea vulnerable marine ecosystem (VME) network along the Apulian margin (central Mediterranean Sea), two low-impact sampling tools were used in three VMEs characterized by cold-water corals (CWC), namely Bari Canyon (BC), [...] Read more.

In order to collect information on fishes and benthopelagic fauna of a deep-sea vulnerable marine ecosystem (VME) network along the Apulian margin (central Mediterranean Sea), two low-impact sampling tools were used in three VMEs characterized by cold-water corals (CWC), namely Bari Canyon (BC), off Monopoli (Mn), and off Santa Maria di Leuca (SML). Using an experimental longline, 53 deployments were carried out between a 314 and 650 m depth for a total of 217 fishing hours, whereas when using the baited lander MEMO (Marine Environment MOnitoring system), 31 deployments were carried out between 427 and 792 m, for a total of 223 h of video recordings. A total of 60 taxa were recorded, comprising 13 Chondrichthyes and 24 Osteichthyes, nine cephalopods, and 14 crustaceans. The similarities in species observed among the VMEs confirm the presence of a network of CWC-VMEs along the Apulian margin, whereas some differences detected are due to the different abundance of some species, such as Galeus melastomus, Helicolenus dactylopterus, and Phycis blennoides. The presence of commercial species, vulnerable/endangered cartilaginous fishes, and large and sexually mature individuals of G. melastomus, H. dactylopterus, and Pagellus bogaraveo in all the VMEs confirms that the network of CWC-VMEs along the Apulian margin can act as a network of refuge areas and an essential fish habitat (EFH) for species threatened by fishing activities. Full article

(This article belongs to the Special Issue Biology and Ecology of Coral Reef Fishes)

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16 pages, 650 KiB

Open AccessFeature PaperArticle

Occurrence of Multi-Drug-Resistant Bacteria in Rainbow Trout–Lettuce Bio-Integrated Culture Systems in Chile

by Christopher Concha, Luz Hurtado, Norma Pérez, German E. Merino and Claudio D. Miranda

Fishes 2024, 9(11), 432; https://doi.org/10.3390/fishes9110432 - 25 Oct 2024

Abstract

In an aquaponic system, fish and plants are cultivated together in a symbiotic environment where they mutually benefit, using significantly less water than traditional farming methods. The main aim of this study was to investigate the occurrence of antimicrobial resistance in two aquaponic [...] Read more.

In an aquaponic system, fish and plants are cultivated together in a symbiotic environment where they mutually benefit, using significantly less water than traditional farming methods. The main aim of this study was to investigate the occurrence of antimicrobial resistance in two aquaponic systems implemented in two Chilean high schools using rainbow trout and lettuce cultures. When water samples (fish tank, biofilter, and plant raft) were analyzed over a three-month period, no resistance to oxytetracycline was detected, whereas the occurrence of resistance to florfenicol was rather small, ranging from 0.01% to 3.1% of bacterial culturable counts. Eighteen isolates were recovered from various sources as representatives of the florfenicol-resistant population, and all of them belonged to the Pseudomonas genus, showing a multi-drug-resistance phenotype and exhibiting simultaneous resistance to 7–13 antimicrobials. All isolates exhibited resistance to amoxicillin, chloramphenicol, florfenicol, and furazolidone and susceptibility to meropenem, oxytetracycline, oxolinic acid, flumequine, ciprofloxacin, and enrofloxacin. Five and two isolates carried the amphenicol-resistance-encoding genes floR and cmlA, respectively, whereas no carriage of integrons or the fexA, fexB, pexA, optrA, and cfr genes encoding for florfenicol resistance was detected. Eleven isolates carried plasmids, but only two of them were able to transfer their plasmid content by conjugation. The knowledge of the microbiome associated with aquaponic systems is still scarce, and their role as potential reservoirs of antimicrobial-resistant bacteria and related genes of these systems must be elucidated. Full article

(This article belongs to the Special Issue Advances in Rainbow Trout)

39 pages, 109622 KiB

Open AccessReview

A Critical Assessment of the Process and Logic Behind Fish Production in Marine Recirculating Aquaculture Systems

by Uwe Waller

Fishes 2024, 9(11), 431; https://doi.org/10.3390/fishes9110431 - 25 Oct 2024

Abstract

A recirculating aquaculture system (RAS) represents a forward-looking form of aquaculture. A RAS consists of fish tanks and water treatment processes in a closed loop to sustain the environmental conditions for fish production. However, the rapid industrialization of the technology is fraught with [...] Read more.

A recirculating aquaculture system (RAS) represents a forward-looking form of aquaculture. A RAS consists of fish tanks and water treatment processes in a closed loop to sustain the environmental conditions for fish production. However, the rapid industrialization of the technology is fraught with transfer problems. This review justifies a RAS process chain based on fish biology. The underlying concept has been evaluated by the author in experimental and commercial RAS projects. The core idea is that the fish must be considered as a technical subcomponent in a RAS, determining the technology. Fish, when considered as small biological machines, are still a black box in many ways. However, their basic biology and physiology provide all the knowledge to implement them in a technical setting. The information required to understand this concept is presented and discussed based on current scientific knowledge. The conclusion is that the technology is available but needs to be rigorously implemented. If this were carried out, fish production in RASs would be ecologically sustainable, which is already claimed for RASs but is not always the reality in commercial applications. Full article

(This article belongs to the Special Issue Advances in Recirculating and Sustainable Aquaculture Systems)

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17 pages, 1611 KiB

Open AccessCommentary

Fishes in Warming Waters, the Gill-Oxygen Limitation Theory and the Debate Around Mechanistic Growth Models

by Johannes Müller and Daniel Pauly

Fishes 2024, 9(11), 430; https://doi.org/10.3390/fishes9110430 - 25 Oct 2024

Abstract

Mechanistic explanations of the impact of climate change on fish growth are currently under debate. However, critical assessments of even the most prominent theories are not always based on accurate interpretations of their underlying mechanistic models. This contribution addresses some of the major [...] Read more.

Mechanistic explanations of the impact of climate change on fish growth are currently under debate. However, critical assessments of even the most prominent theories are not always based on accurate interpretations of their underlying mechanistic models. This contribution addresses some of the major misunderstandings still causing the Gill-Oxygen Limitation Theory (GOLT) from being examined based on its actual structuring elements and assumptions, rather than erroneous perceptions. As we argue, recent critiques of the GOLT are based on implausible interpretations of respirometry data that are invoked to distinguish maintenance costs and overhead costs of growth. Discussing the current state of the debate, we emphasize the fact that fasting young and, thus, growing fish for short periods of time is not sufficient to suppress energy (i.e., oxygen) allocation to growth. In the process of dealing with these issues, several cases of apparent ‘counter-evidence’ are discussed. Highlighting the need to base critical discussions and examinations of the GOLT on its actual predictions, we recommend that testing the theory should focus on broad reviews or meta-analyses, e.g., on datasets of gill surface area and the relationship of these data to growth performance under different temperature regimes. Full article

(This article belongs to the Section Environment and Climate Change)

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20 pages, 811 KiB

Open AccessArticle

Consumers’ Attitudes Towards Prawn Consumption in Bangladesh: An Investigation on Perceived Value and Willingness-to-Pay

by Md Taj Uddin, Sima Roy and Aurup Ratan Dhar

Fishes 2024, 9(11), 429; https://doi.org/10.3390/fishes9110429 - 25 Oct 2024

Abstract

This study assessed consumer preferences and consumption patterns for prawns in Bangladesh, underscoring the economic and nutritional significance of prawns in the local diet. A total of 120 respondents were interviewed following a random sampling technique from four districts. The data analysis employed [...] Read more.

This study assessed consumer preferences and consumption patterns for prawns in Bangladesh, underscoring the economic and nutritional significance of prawns in the local diet. A total of 120 respondents were interviewed following a random sampling technique from four districts. The data analysis employed descriptive statistics alongside mathematical and statistical methods. The findings indicate a strong preference for fresh and large-sized prawns among the consumers. Income level substantially influenced the prawn purchases, with the high-income consumers more likely to buy premium prawn products, while the low-income consumers showed sensitivity to price changes. The primary concerns that significantly influenced the consumers’ purchasing decisions were found to be size, freshness, taste, price, market availability, and income. Additionally, the consumers’ perceived value and willingness-to-pay for prawns were significantly driven by size, freshness, environmental sustainability, and income levels. Policy recommendations include promoting sustainable prawn farming and improving accessibility for low-income consumers to enhance both nutritional intake and economic resilience. This research offers valuable insights for stakeholders in the prawn industry, facilitating the development of targeted marketing strategies and informed policymaking for sustainable industry growth. Full article

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14 pages, 1085 KiB

Open AccessArticle

Age, Growth, Sex Composition, and Diet of the Burbot, Lota lota, the Only Freshwater Species of the Family Lotidae in the Amur (Heilongjiang) River, Northeast China

by Lei Li, Huili Shao, Pavel B. Mikheev, Zepeng Zhang, Hongyu Jin and Wanqiao Lu

Fishes 2024, 9(11), 428; https://doi.org/10.3390/fishes9110428 - 24 Oct 2024

Abstract

Information about the population structure, including the age and sex composition, growth characteristics, and diet of fish, is essential for the conservation and sustainable exploitation of fish stock. The burbot, Lota lota, is the only freshwater species of the family Lotidae in [...] Read more.

Information about the population structure, including the age and sex composition, growth characteristics, and diet of fish, is essential for the conservation and sustainable exploitation of fish stock. The burbot, Lota lota, is the only freshwater species of the family Lotidae in the Amur (Heilongjiang) River catchment located in northeastern China. Information on the biological characteristics and data on the population structure of this fish from the Amur River are scarce. To study these factors in burbot, Lota lota, in the Amur River of China, 749 specimens from four sampling areas were taken and analyzed in October 2022, January 2023, and May 2023. The ages of the sampled fish ranged from 1+ to 7+ years. The female/male ratio was 1.04:1, and body length and mass varied from 175 to 595 mm and 73.5 to 1958.7 g, respectively. The length–weight regression parameter b value was estimated as 2.80. The parameters of the von Bertalanffy growth model were L_∞ = 596, K = 0.221, and t₀ = −0.771 for all sampled fish; L_∞ = 625, K = 0.208, and t₀ = −0.756 for females; and L_∞ = 584, K = 0.219, and t₀ = −0.980 for males. The analysis of the stomach contents showed fish to be the major source of nutrition across all areas and sampling periods. In January, the secondary prey of burbots in the Huma reach of the upper Amur River was aquatic insect larvae, while, in the Tongjiang and Fuyuan reaches of the middle Amur River, the secondary prey was shrimp. The mean stomach fullness index and rate of empty stomachs differed with the sampling area, with the greatest proportion of empty stomachs observed in the Luobei reach of the middle Amur River, and the lowest in the Tongjiang and Fuyuan reaches. The mean stomach fullness index showed the opposite trend. In the Huma reach, the contributions of fish to the diet and the mean stomach fullness index were significantly higher in May than in October and January. The study provides the first detailed information on the population age and sex structure, growth patterns, and feeding ecology of burbots from the Amur River, China. The results will aid in formulating management strategies and regulations for local populations of burbots in the Amur River, China. Full article

(This article belongs to the Section Biology and Ecology)

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13 pages, 8340 KiB

Open AccessArticle

Reducing Total Dissolved Gas and Gas Bubble Trauma in a Regulated River

by Paul C. Kusnierz

Fishes 2024, 9(11), 427; https://doi.org/10.3390/fishes9110427 (registering DOI) - 24 Oct 2024

Abstract

When water is spilled over dams, atmospheric gases can become entrained, resulting in supersaturated water. Total dissolved gas (TDG) > 110% saturation can cause gas bubble trauma (GBT) in fish. The negative effects of GBT include increased buoyancy, decreased swimming performance, and possible [...] Read more.

When water is spilled over dams, atmospheric gases can become entrained, resulting in supersaturated water. Total dissolved gas (TDG) > 110% saturation can cause gas bubble trauma (GBT) in fish. The negative effects of GBT include increased buoyancy, decreased swimming performance, and possible mortality. The lower Clark Fork River (LCFR) in Idaho frequently has TDG > 110% saturation due to the spill at Cabinet Gorge Dam as well as from upstream facilities. Spillway crests on Cabinet Gorge Dam were modified to reduce TDG production and the potential harm from GBT. To evaluate the effectiveness of spillway crest modifications, relationships between river discharge and measured TDG were developed pre- and post-modification and used to calculate the predicted TDG in the LCFR pre- and post-modification under two spill season discharge scenarios. The predicted TDG for the scenarios was used with an established TDG-GBT relationship for the LCFR to estimate the expected GBT incidence. Generally, TDG was lower post-modification, and the discharge at which 110% and 120% saturation were exceeded increased by about 198 m³/s. Modification also reduced the number of days with elevated TDG. The lower TDG post-modification resulted in significant (p < 0.05) reductions in the probability of observing GBT. The modification of Cabinet Gorge Dam spillway crests reduced TDG production over a range of discharges and has resulted in improved conditions for fish downstream of the dam. Full article

(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)

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18 pages, 360 KiB

Open AccessArticle

Factors Influencing Consumers’ Purchases of Snook (Centropomus viridis) and Red Snapper (Lutjanus peru) from Artisanal Aquaculture Cooperatives in Mexico

by Marco Antonio Almendarez-Hernández, Ismael Sánchez-Brito, René Arturo Kachok-Gavarain, Deneb Maldonado-García, Carolina Sánchez-Verdugo and Minerva Concepción Maldonado-García

Fishes 2024, 9(11), 426; https://doi.org/10.3390/fishes9110426 - 24 Oct 2024

Abstract

Aquaculture in developing countries, including Mexico, primarily consists of artisanal activities characterized by low-scale production. No studies in these regions has analyzed consumer preferences regarding aquaculture products, specifically for snook and red snapper. Consequently, to explore consumer preferences, the primary objective of this [...] Read more.

Aquaculture in developing countries, including Mexico, primarily consists of artisanal activities characterized by low-scale production. No studies in these regions has analyzed consumer preferences regarding aquaculture products, specifically for snook and red snapper. Consequently, to explore consumer preferences, the primary objective of this study is to estimate a measure of welfare in the form of willingness to pay (WTP) for fish cultivated under small-scale production conditions in floating cages. To examine the variables impacting WTP, we employed the random utility model (RUM) theoretical framework and a grouping of econometric models belonging to the discrete choice framework. The results strongly suggest that product attributes, such as presentation, purchasing location, consumption-related characteristics, and certain socioeconomic variables, significantly influence the decision to select farmed products. Developing productive aquaculture projects in Mexico and other developing countries can enhance community development by providing producers with accurate information for decision-making and by expanding the fish supply in response to the growing consumer demand. Full article

(This article belongs to the Section Sustainable Aquaculture)

13 pages, 2131 KiB

Open AccessArticle

Developmental Toxicity and Teratogenic Effects of Dicarboximide Fungicide Iprodione on Zebrafish (Danio rerio) Embryos

by Chang-Young Yoon, Kyongmi Chon, Bala Murali Krishna Vasamsetti, Sojeong Hwang, Kyeong-Hun Park and Kee Sung Kyung

Fishes 2024, 9(11), 425; https://doi.org/10.3390/fishes9110425 - 23 Oct 2024

Abstract

Iprodione (IDN) is a broad-spectrum fungicide used to treat various fungal infections in plants. Despite its extensive use, assessment of its toxicity in aquatic organisms remains incomplete. This study investigated the deleterious effects of IDN using zebrafish (ZF) as a model organism. ZF [...] Read more.

Iprodione (IDN) is a broad-spectrum fungicide used to treat various fungal infections in plants. Despite its extensive use, assessment of its toxicity in aquatic organisms remains incomplete. This study investigated the deleterious effects of IDN using zebrafish (ZF) as a model organism. ZF embryos, beginning at 2 h post-fertilization (hpf), were exposed to IDN (3.75–40 mg/L), and both mortality and deformities were assessed. The impact of IDN on mortality was concentration-dependent and significant from 14 mg/L. Importantly, IDN induced several deformities at sublethal concentrations, including abnormal somites, reduced retinal pigment accumulation, yolk sac edema, hatching failure, abnormal swim bladders, and spinal curvature. The EC₅₀ values for IDN-induced deformities were 3.44 ± 0.74 to 21.42 ± 6.00 mg/L. The calculated teratogenic index values for all deformities were above 1, indicating that IDN is teratogenic to ZF. IDN-exposed ZF also displayed abnormalities in touch-evoked escape responses. IDN significantly affected heart rate and blood flow, and induced pericardial edema and hyperemia in a concentration-dependent manner, suggesting its influence on cardiac development and the function of ZF. In conclusion, these results suggest that IDN exerts toxic effects on ZF embryos, affecting mortality, development, and behavior. Full article

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13 pages, 4441 KiB

Open AccessArticle

Acoustic Target Strength Measurement of Larmichthys crocea Based on the Kirchhoff-Ray Mode Model

by Junliang Meng, Yong Tang, Lizhi Sun, Longshan Lin, Yuan Li, Xing Miao, Shigang Liu and Puqing Song

Fishes 2024, 9(11), 424; https://doi.org/10.3390/fishes9110424 - 22 Oct 2024

Abstract

Larmichthys crocea (L. crocea) is an economically important fish species mainly distributed off the coast of China. In this study, 11 L. crocea samples of different body lengths were collected from aquaculture cages in the East China Sea to measure the [...] Read more.

Larmichthys crocea (L. crocea) is an economically important fish species mainly distributed off the coast of China. In this study, 11 L. crocea samples of different body lengths were collected from aquaculture cages in the East China Sea to measure the acoustic target strength (TS). Using the Kirchhoff-Ray mode (KRM) model, the directional TS of L. crocea was measured at frequencies of 70 kHz, 120 kHz, and 200 kHz. Furthermore, the relationships between TS and body length were determined using the least squares method and the standard b₂₀ equation. The results showed that the TS of L. crocea varied with tilt angle, frequency, and body length. For tilt angles ranging from (−5°, 15°), the equation for fitting TS and body length using the least squares method were TS = 32.99·log₁₀L − 87.36 (70 kHz), TS = 33.26·log₁₀L − 87.77 (120 kHz), and TS = 39.46·log₁₀L − 95.51 (200 kHz). They were expressed in the standard b₂₀ equation as TS = 20·log₁₀L − 71.16 (70 kHz), TS = 20·log₁₀L − 71.23 (120 kHz), and TS = 20·log₁₀L − 71.24 (200 kHz). For tilt angles ranging from (0°, 10°), the equation for fitting TS and body length using the least squares method is TS = 28.69·log₁₀L − 81.71 (70 kHz), TS = 32.30·log₁₀L − 86.44 (120 kHz), and TS = 45.87·log₁₀L − 103.73 (200 kHz). They were expressed in the standard b₂₀ equation as TS = 20·log₁₀L − 70.88 (70 kHz), TS = 20·log₁₀L − 71.10 (120 kHz), and TS = 20·log₁₀L − 71.48 (200 kHz). Moreover, the 18–300 kHz spectral curve showed a decreasing trend in the frequency range from 18 kHz to 30 kHz, while maintaining relatively stable fluctuations in the other frequency ranges. These findings offer a comprehensive understanding of the scattering characteristics of L. crocea and provide a reliable reference of TS for the fishery acoustic assessment of L. crocea. Full article

(This article belongs to the Special Issue Underwater Acoustic Technologies for Sustainable Fisheries)

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18 pages, 4241 KiB

Open AccessArticle

Sustainability Assessment of Brown Trout Populations in Serbia (Central Balkans) Using the Modified ESHIPPO Model

by Tijana Veličković, Saša Marić, David Stanković, Aleksandra Milošković, Milena Radenković, Radek Šanda, Jasna Vukić, Simona Đuretanović, Nataša Kojadinović, Marija Jakovljević and Vladica Simić

Fishes 2024, 9(11), 423; https://doi.org/10.3390/fishes9110423 - 22 Oct 2024

Abstract

In the inland waters of the Balkans, many brown trout populations have been severely depleted. Therefore, identifying potential threats to their continued survival and ranking populations based on their biological and evolutionary importance enables setting conservation priorities. To assess the sustainability of the [...] Read more.

In the inland waters of the Balkans, many brown trout populations have been severely depleted. Therefore, identifying potential threats to their continued survival and ranking populations based on their biological and evolutionary importance enables setting conservation priorities. To assess the sustainability of the brown trout populations in the territory of Serbia (central Balkans), a modification of the ESHIPPO model was performed. The main modification involves incorporating the investigated populations’ genetic structure into the model. Therefore, the new ESHIPPOsalmo model includes an analysis of biological parameters and the impact of multiple factors, including habitat alterations, invasive species, pollution, human population growth, and over-exploitation. In order to investigate individual levels of influence of the model’s analyzed parameters, a combination of supervised and unsupervised machine learning methods was used. The structure of the model is based on general and easily measurable indicators, which enables its application in any salmonid river in the world. By evaluating the parameters of the ESHIPPOsalmo model, we were able to establish that, of the analyzed populations from 46 localities, 37% have a moderate level of sustainability, 43% low, and 20% critically low. Full article

(This article belongs to the Special Issue The Roles of Fishery Biology and Fish Population Dynamics in Fisheries Management)

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15 pages, 295 KiB

Open AccessReview

Evaluation of Fish Biodiversity in Estuaries Through Environmental DNA Metabarcoding: A Comprehensive Review

by Asma Massad Alenzi

Fishes 2024, 9(11), 422; https://doi.org/10.3390/fishes9110422 - 22 Oct 2024

Abstract

Traditional methods face difficulties in capturing elusive species and navigating the complexities of estuarine environments. The adoption of eDNA metabarcoding has revolutionized biodiversity assessment, offering non-invasive and comprehensive sampling. Challenges specific to estuaries, such as sediment loads and salinity fluctuations, were initially addressed [...] Read more.

Traditional methods face difficulties in capturing elusive species and navigating the complexities of estuarine environments. The adoption of eDNA metabarcoding has revolutionized biodiversity assessment, offering non-invasive and comprehensive sampling. Challenges specific to estuaries, such as sediment loads and salinity fluctuations, were initially addressed through improved DNA extraction, optimized primers, and specialized bioinformatics tools. The integration of multiple genetic markers and quantitative eDNA approaches has enhanced resolution, enabling the detection of rare and cryptic species. Standardized sampling protocols and validation through traditional methods contribute to the reliability of eDNA metabarcoding. This technology holds promise for informing conservation and management strategies in estuarine ecosystems by providing timely and cost-effective biodiversity data. Full article

(This article belongs to the Section Fishery Facilities, Equipment, and Information Technology)

11 pages, 2122 KiB

Open AccessArticle

Species Composition of Fish Larvae and Juveniles in the Nanji Islands, China

by Xiaodong Wang, Dubin Zhao, Qiang Liu, Tianyu Lu, Junsheng Zhong, Wandong Chen, Shangwei Xie and Shun Chen

Fishes 2024, 9(11), 421; https://doi.org/10.3390/fishes9110421 - 22 Oct 2024

Abstract

To describe the species composition of fish larvae and juveniles in the Nanji Islands, monthly collection was conducted at 12 stations around the Nanji Islands from March 2023 to February 2024 by using horizontal tow at the surface layer. The fish larvae and [...] Read more.

To describe the species composition of fish larvae and juveniles in the Nanji Islands, monthly collection was conducted at 12 stations around the Nanji Islands from March 2023 to February 2024 by using horizontal tow at the surface layer. The fish larvae and juveniles were collected by a larva net (1.3 m mouth diameter, 0.5 mm mesh aperture). A total of 6446 fish larvae and juveniles were collected, belonging to 59 species and 54 genera in 11 families. Most of them were preflexion larvae (93.31%). Gobiidae, with eight species, was the most diverse family. Based on the index of relative importance (IRI) result, the dominant species was Sebastiscus marmoratus (Cuvier, 1829), accounting for 84.52% of the total number of samples collected. The common species were Stolephorus commersonii Lacepède, 1803; Omobranchus elegans (Steindachner, 1876); Nibea albiflora (Richardson, 1846); Parablennius yatabei (Jordan & Snyder, 1900); Lateolabrax maculatus (McClelland, 1844); and Odontamblyopus lacepediiand (Temminck & Schlegel, 1845). Other species were all rare species. The highest species number was in September (18 species), and the highest density was in December. Only one fish larva was collected in April. Pielou’s evenness index was highest in November, while Margalef’s richness index and Shannon–Wiener diversity were highest in September. The result of cluster analysis showed that the 11 months (except April) could be divided into four groups. The species number, density, and three diversity indexes showed no significant correlation with temperature and salinity. Full article

(This article belongs to the Special Issue Biodiversity and Spatial Distribution of Fishes)

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Fishes, Volume 9, Issue 11 (November 2024) – 16 articles

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