Fishes

13 pages, 3270 KB

Open AccessEditor’s ChoiceArticle

Secondary Production and Biomass Dynamics of Mediterranean Brown Trout (Salmo trutta Complex) in Pyrenean Headwater Streams

by Enric Aparicio, Rafel Rocaspana and Carles Alcaraz

Fishes 2025, 10(10), 476; https://doi.org/10.3390/fishes10100476 - 23 Sep 2025

Cited by 4 | Viewed by 1017

Abstract

Fish secondary production integrates multiple demographic parameters, including population density, growth, mortality, and recruitment, and thereby provides a comprehensive measure of ecological performance. It is also a valuable tool for assessing the ecological integrity of stream ecosystems and the responses of fish populations [...] Read more.

Fish secondary production integrates multiple demographic parameters, including population density, growth, mortality, and recruitment, and thereby provides a comprehensive measure of ecological performance. It is also a valuable tool for assessing the ecological integrity of stream ecosystems and the responses of fish populations to habitat alteration, climatic variability, and anthropogenic pressures. Despite its relevance, empirical estimates of fish production remain limited due to methodological constraints. In this study, we quantified secondary production and production-to-biomass (P/B) ratios for Mediterranean brown trout (Salmo trutta complex) across six headwater stream reaches in the northeastern Iberian Peninsula, characterized by contrasting hydrological regimes, channel morphology, and water chemistry. Field sampling was conducted over two consecutive annual cycles (2008/2009 and 2009/2010) at all sites, with extended monitoring at two reaches until 2017 to assess long-term variability. Annual trout production, over the two consecutive annual cycles, ranged from 30.9 to 167.8 kg ha⁻¹ year⁻¹ (mean = 82.2 kg ha⁻¹ year⁻¹), and mean P/B ratios ranged from 0.61 to 1.13 (mean = 0.80). These values fall within the intermediate range reported for brown trout globally and reflect the constrained energy dynamics of Mediterranean streams. Higher production was generally associated with strong age-1 recruitment, elevated standing biomass, and greater water alkalinity. Long-term analyses revealed that interannual variation in trout production was significantly correlated with discharge variability, with higher production occurring under more stable flow conditions. However, in addition to flow variability other factors, such as habitat complexity, may modulate local productivity. Consequently, interannual fluctuations at the long-term sites revealed substantial demographic variability influenced by site-specific environmental conditions. These findings offer reference baselines for Mediterranean trout populations and contribute to the ecological basis for their conservation and management. 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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25 pages, 11592 KB

Open AccessEditor’s ChoiceArticle

Pascua marecoralliensis, a New Species of Goby (Gobiiformes, Gobiidae) from the Central Coral Sea with Validation of the Genus Pascua

by Christopher H. R. Goatley, Andrea I. Varela, Javier Sellanes and Luke Tornabene

Fishes 2025, 10(9), 449; https://doi.org/10.3390/fishes10090449 - 4 Sep 2025

Cited by 1 | Viewed by 3447

Abstract

In this paper, we use molecular phylogenetics, micro-CT scanning, and morphological analyses to describe a new species of goby, Pascua marecoralliensis, and demonstrate that the genus Pascua is distinct from Hetereleotris, as supported by five diagnostic characters, including modified basicaudal scales [...] Read more.

In this paper, we use molecular phylogenetics, micro-CT scanning, and morphological analyses to describe a new species of goby, Pascua marecoralliensis, and demonstrate that the genus Pascua is distinct from Hetereleotris, as supported by five diagnostic characters, including modified basicaudal scales and reduced sensory papillae patterns. Phylogenetic analysis places Pascua as sister to the Gobiodon group, while Hetereleotris forms a separate clade. The new species, P. marecoralliensis, differs from congeners in fin ray counts, cephalic pore patterns, and head morphology and exhibits unique live colouration. Additionally, we reclassify Hetereleotris readerae and H. sticta as Pascua readerae and P. sticta based on shared genus-specific traits. The distribution of Pascua spans the southern Pacific, suggesting a relict lineage or undiscovered diversity in the genus. This work underscores the importance of integrative taxonomic approaches for resolving cryptic diversity in gobioid fishes and highlights the need for further sampling in understudied regions. Full article

(This article belongs to the Section Taxonomy, Evolution, and Biogeography)

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14 pages, 813 KB

Open AccessEditor’s ChoiceArticle

The Influence of Different Feeding Time Management on the Growth and Stress Response of the African Catfish Clarias gariepinuns (Burchel, 1822) Under Farming Conditions

by Marc-C. Hildebrand, David Runge, Björn Bassmann and Harry W. Palm

Fishes 2025, 10(8), 414; https://doi.org/10.3390/fishes10080414 - 18 Aug 2025

Cited by 2 | Viewed by 3202

Abstract

In this study, the growth and welfare of the African catfish (Clarias gariepinus, Burchell 1822) were investigated under industrial farming conditions. For this purpose, the growing success (cm, g) and typical stress related parameters (glucose-, lactate-, cortisol-concentrations, growth hormone, HSI-liver index) [...] Read more.

In this study, the growth and welfare of the African catfish (Clarias gariepinus, Burchell 1822) were investigated under industrial farming conditions. For this purpose, the growing success (cm, g) and typical stress related parameters (glucose-, lactate-, cortisol-concentrations, growth hormone, HSI-liver index) were investigated on the African catfish (102–841 g) in relation to an external stressor (working light and noise) and different feeding regimes (day, night, and day and night feeding) over 83 days. As no significant effects were found among the experimental feeding treatments in relation to the growth performance and investigated stress parameters, the time of feeding seems to have less impact to the production success and stress reactions as suggested before. Regarding our results, the effect of feeding conditioning could have played a strong factor likewise the ageing process of the reared fish species which is known to be rather photophobic. Therefore, the factor of conditioning and its influence to the time shift in feeding regimes and the impact of noise and light stressors during feeding should be investigated separately in future experiments to obtain further results in this context and clarify the validity of the best feeding conditions for African catfish. Full article

(This article belongs to the Special Issue Physiological Response Mechanisms of Aquatic Animals to Stress)

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23 pages, 676 KB

Open AccessFeature PaperEditor’s ChoiceReview

Stunted Versus Normally Growing Fish: Adapted to Different Niches

by Bror Jonsson

Fishes 2025, 10(8), 376; https://doi.org/10.3390/fishes10080376 - 4 Aug 2025

Cited by 4 | Viewed by 4104

Abstract

This literature-based review draws on studies of thirty-four fish species; most are from northern temperate regions. Fish have flexible and indeterminate growth, and often they do not reach their growth and size potential. They may become stunted with impaired growth and early maturity, [...] Read more.

This literature-based review draws on studies of thirty-four fish species; most are from northern temperate regions. Fish have flexible and indeterminate growth, and often they do not reach their growth and size potential. They may become stunted with impaired growth and early maturity, chiefly as a phenotypically plastic reaction. The main causes of stunted growth are negatively density-dependent food availability and keen intraspecific competition leading to environmental stress. Typically, their growth levels off early in life as energy consumptions approach energy costs of maintenance. Females typically attain maturity soon after the energy surplus from feeding starts to decrease. Males are often more variable in size at maturity owing to alternative mating strategies, and their size at maturity depends on both species-specific mating behaviours and environmental opportunities. In polyphenic/polymorphic populations, one phenotype may be stunted and the other phenotype non-stunted; stunted individuals do not perform the required ontogenetic niche shift needed to grow larger. The adult morphology of stunted fish is typically like the morphology of juveniles. Their secondary sexual characters are less pronounced, and they phenotypically retain adaptation to their early feeding niche, which is different from that of large-growing individuals. There are open questions regarding to what extent genetics and epigenetics regulate the life histories of stunted phenotypes. Full article

(This article belongs to the Special Issue Habitat as a Template for Life Histories of Fish)

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21 pages, 1379 KB

Open AccessEditor’s ChoiceArticle

Stream Temperature, Density Dependence, Catchment Size, and Physical Habitat: Understanding Salmonid Size Variation Across Small Streams

by Kyle D. Martens and Warren D. Devine

Fishes 2025, 10(8), 368; https://doi.org/10.3390/fishes10080368 - 1 Aug 2025

Cited by 1 | Viewed by 1861

Abstract

The average body size (fork length) of juvenile salmonids in small streams varies across landscapes and can be influenced by stream temperature, density dependence, catchment size, and physical habitat. In this study, we compared sets of 16 mixed-effects linear models representing these four [...] Read more.

The average body size (fork length) of juvenile salmonids in small streams varies across landscapes and can be influenced by stream temperature, density dependence, catchment size, and physical habitat. In this study, we compared sets of 16 mixed-effects linear models representing these four potentially influencing indicators for three species/age classes to assess the relative importance of their influences on body size. The global model containing all indicators was the most parsimonious model for juvenile coho salmon (Oncorhynchus kisutch; R²m = 0.4581, R²c = 0.5859), age-0 trout (R²m = 0.4117, R²c = 0.5968), and age-1 or older coastal cutthroat trout (O. clarkii; R²m = 0.2407, R²c = 0.5188). Contrary to expectations, salmonid density, catchment size, and physical habitat metrics contributed more to the top models for both coho salmon and age-1 or older cutthroat trout than stream temperature metrics. However, a stream temperature metric, accumulated degree days, had the only significant relationship (positive) of the indicators with body size in age-0 trout (95% CI 1.58 to 23.04). Our analysis identifies complex relationships between salmonid body size and environmental influences, such as the importance of physical habitat such as pool size and boulders. However, management or restoration actions aimed at improving or preventing anticipated declines in physical habitat such as adding instream wood or actions that may lead to increasing pool area have potential to ensure a natural range of salmonid body sizes across watersheds. Full article

(This article belongs to the Special Issue Habitat as a Template for Life Histories of Fish)

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27 pages, 1569 KB

Open AccessEditor’s ChoiceReview

Bisphenols: Endocrine Disruptors and Their Impact on Fish: A Review

by Nikola Peskova and Jana Blahova

Fishes 2025, 10(8), 365; https://doi.org/10.3390/fishes10080365 - 29 Jul 2025

Cited by 10 | Viewed by 6325

Abstract

Bisphenols (BPs), particularly bisphenol A (BPA) and its structural analogues, are synthetic compounds widely used in plastics and industrial materials. These substances are also recognised as endocrine-disrupting chemicals (EDCs) due to their ability to interfere with hormonal systems, which has significant implications for [...] Read more.

Bisphenols (BPs), particularly bisphenol A (BPA) and its structural analogues, are synthetic compounds widely used in plastics and industrial materials. These substances are also recognised as endocrine-disrupting chemicals (EDCs) due to their ability to interfere with hormonal systems, which has significant implications for aquatic organisms. This review summarises the occurrence, environmental distribution, and toxicity of BPs in fish, with a focus on estrogenic, androgenic, thyroid, and glucocorticoid disruptions. Studies consistently show that exposure to BPs leads to altered gene expression, developmental abnormalities, impaired reproduction, and disrupted hormonal signalling in various fish species. Although BPA alternatives like bisphenol S, bisphenol F, or bisphenol AF were introduced as safer options, emerging evidence suggests they may pose equal or greater risks. Regulatory measures are evolving, particularly within the European Union, but legislation remains limited for many bisphenol analogues. This review emphasises the need for comprehensive environmental monitoring, stricter regulatory frameworks, and the development of genuinely safer alternatives to minimise the ecological and health impacts of BPs in aquatic systems. Full article

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

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16 pages, 993 KB

Open AccessEditor’s ChoiceReview

The Application of Digital Twin Technology in the Development of Intelligent Aquaculture: Status and Opportunities

by Jianlei Chen, Yong Xu, Hao Li, Xinguo Zhao, Yang Su, Chunhao Qi, Keming Qu and Zhengguo Cui

Fishes 2025, 10(8), 363; https://doi.org/10.3390/fishes10080363 - 25 Jul 2025

Cited by 22 | Viewed by 6804

Abstract

Aquaculture is vital for global food security but faces challenges like disease, water quality control, and resource optimization. Digital twin technology, a real-time virtual replica of physical aquaculture systems, emerges as a transformative solution. By integrating sensors and data analytics, it enables monitoring [...] Read more.

Aquaculture is vital for global food security but faces challenges like disease, water quality control, and resource optimization. Digital twin technology, a real-time virtual replica of physical aquaculture systems, emerges as a transformative solution. By integrating sensors and data analytics, it enables monitoring and optimization of water quality, feed efficiency, fish health, and operations. This review explores the current adoption status of digital twins in aquaculture, highlighting applications in real-time monitoring and system optimization. It addresses key implementation challenges, including data integration and scalability, and identifies emerging opportunities for advancing sustainable, intelligent aquaculture practices. Full article

(This article belongs to the Special Issue Application of Artificial Intelligence in Aquaculture)

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19 pages, 2552 KB

Open AccessEditor’s ChoiceArticle

The Biogeographic Patterns of Two Typical Mesopelagic Fishes in the Cosmonaut Sea Through a Combination of Environmental DNA and a Trawl Survey

by Yehui Wang, Chunlin Liu, Mi Duan, Peilong Ju, Wenchao Zhang, Shuyang Ma, Jianchao Li, Jianfeng He, Wei Shi and Yongjun Tian

Fishes 2025, 10(7), 354; https://doi.org/10.3390/fishes10070354 - 17 Jul 2025

Viewed by 2091

Abstract

Investigating biodiversity in remote and harsh environments, particularly in the Southern Ocean, remains costly and challenging through traditional sampling methods such as trawling. Environmental DNA (eDNA) sampling, which refers to sampling genetic material shed by organisms from environmental samples (e.g., water), provides a [...] Read more.

Investigating biodiversity in remote and harsh environments, particularly in the Southern Ocean, remains costly and challenging through traditional sampling methods such as trawling. Environmental DNA (eDNA) sampling, which refers to sampling genetic material shed by organisms from environmental samples (e.g., water), provides a more cost-effective and sustainable alternative to traditional sampling approaches. To study the biogeographic patterns of two typical mesopelagic fishes, Antarctic lanternfish (Electrona antarctica) and Antarctic deep-sea smelt (Bathylagus antarcticus), in the Cosmonaut Sea in the Indian Ocean sector of the Southern Ocean, we conducted both eDNA and trawling sampling at a total of 86 stations in the Cosmonaut Sea during two cruises in 2021–2022. Two sets of species-specific primers and probes were developed for a quantitative eDNA analysis of two fish species. Both the eDNA and trawl results indicated that the two fish species are widely distributed in the Cosmonaut Sea, with no significant difference in eDNA concentration, biomass, or abundance between stations. Spatially, E. antarctica tended to be distributed in shallow waters, while B. antarcticus tended to be distributed in deep waters. Vertically, E. antarctica was more abundant above 500 m, while B. antarcticus had a wider range of habitat depths. The distribution patterns of both species were affected by nutrients, with E. antarctica additionally affected by chlorophyll, indicating that their distribution is primarily influenced by food resources. Our study provides broader insight into the biogeographic patterns of the two mesopelagic fishes in the remote Cosmonaut Sea, demonstrates the potential of combining eDNA with traditional methods to study biodiversity and ecosystem dynamics in the Southern Ocean and even at high latitudes, and contributes to future ecosystem research and biodiversity conservation in the region. Full article

(This article belongs to the Section Biology and Ecology)

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24 pages, 1937 KB

Open AccessEditor’s ChoiceArticle

Asparagopsis taxiformis Feed Supplementation as a Tool to Improve the Resilience of Farmed Diplodus sargus to Marine Heatwave Events—A Metabolomics Approach

by Marta Dias, Isa Marmelo, Carla António, Ana M. Rodrigues, António Marques, Mário S. Diniz and Ana Luísa Maulvault

Fishes 2025, 10(7), 350; https://doi.org/10.3390/fishes10070350 - 15 Jul 2025

Cited by 3 | Viewed by 2690

Abstract

The need to maximize aquaculture production while addressing environmental and food security challenges posed by climate change has driven research towards the development of functional aquafeeds that enhance performance and immunity in farmed species. However, exposure to dietary and environmental stressors affects marine [...] Read more.

The need to maximize aquaculture production while addressing environmental and food security challenges posed by climate change has driven research towards the development of functional aquafeeds that enhance performance and immunity in farmed species. However, exposure to dietary and environmental stressors affects marine organisms, altering key metabolic pathways best understood through high-throughput “omics” tools. This study assessed the effects of Asparagopsis taxiformis supplementation on central metabolic pathways by analyzing changes in primary metabolite levels in the liver of farmed Diplodus sargus under optimal and suboptimal temperature conditions. Results showed that seaweed supplementation had a beneficial effect on the fish’s primary metabolome; however, inclusion levels and rearing conditions played a crucial role in determining outcomes. While 1.5% supplementation maintained a balanced primary metabolome under optimal temperature conditions, 3.0% supplementation most effectively mitigated the adverse effects of acute thermal stress during a marine heatwave. These findings highlight the nutritive and functional potential of A. taxiformis supplementation in aquafeeds for marine omnivorous fish species and emphasize the importance of evaluating functional aquafeeds under suboptimal rearing conditions. Overall, our results demonstrate the value of metabolomics in elucidating the molecular basis underlying biological pathways in farmed marine fish and optimizing production through climate-smart dietary strategies. Full article

(This article belongs to the Special Issue Advances in Aquaculture Feed Additives)

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55 pages, 3773 KB

Open AccessEditor’s ChoiceReview

Molecular Mechanisms and Biomarker-Based Early-Warning Indicators of Heavy Metal Toxicity in Marine Fish

by Andra Oros, Valentina Coatu, Nicoleta Damir, Diana Danilov, Elena Ristea and Luminita Lazar

Fishes 2025, 10(7), 339; https://doi.org/10.3390/fishes10070339 - 10 Jul 2025

Cited by 36 | Viewed by 8024

Abstract

Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which [...] Read more.

Heavy metals are among the most persistent and bioaccumulative pollutants in marine ecosystems, posing significant toxicological threats to fish via complex molecular and cellular disruptions. This review synthesizes current knowledge on the cascade of mechanistic responses in marine fish following HM exposure, which includes oxidative stress, modulation of antioxidant responses, activation of detoxification systems, DNA damage, inflammation, apoptosis, neuroendocrine disruption, and ultimately, cellular energy imbalance. In addition to established pathways, the review highlights recent advances in mechanistic understanding and biomarker development, including cellular stress responses, epigenetic regulation, metal homeostasis mechanisms, and novel molecular indicators. These mechanisms support the development of an integrated biomarker framework that combines classical indicators (e.g., antioxidant enzymes, metallothionein) with next-generation endpoints (e.g., miRNA profiles, gene-level responses of metal transporters or stress chaperones, epigenetic alterations). The interpretation of biomarker responses requires consideration of the exposure context, environmental variables, and physiological status to ensure accurate assessment of sublethal toxicity in field settings. By bridging mechanistic understanding with biomonitoring relevance, this review provides a comprehensive foundation for advancing molecular tools in pollution monitoring and risk assessment. Special emphasis is placed on biomarkers specific to heavy metal exposure, enhancing their diagnostic value relative to general stress indicators. Full article

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

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14 pages, 665 KB

Open AccessEditor’s ChoiceArticle

Evaluation of Three Atlantic Salmon Strains for Resistance to Copepodid Sea Lice Attachment

by Michael R. Pietrak, Thomas A. Delomas, Demitri Lifgren and Mark P. Polinski

Fishes 2025, 10(7), 334; https://doi.org/10.3390/fishes10070334 - 8 Jul 2025

Viewed by 2184

Abstract

Sea lice have been a persistent pest of the salmon farming industry for more than 50 years. In this study, we aimed to identify if different strains of Atlantic salmon with discrete long-term lice exposure histories had variable resistance to copepodid attachment and/or [...] Read more.

Sea lice have been a persistent pest of the salmon farming industry for more than 50 years. In this study, we aimed to identify if different strains of Atlantic salmon with discrete long-term lice exposure histories had variable resistance to copepodid attachment and/or different attachment-specific transcriptome patterns. We additionally sought to characterize lice distributions on fins, head, and skin and identify if attachment location influenced transcriptomic profiles of lice. Lice counts were correlated with body size and highest on St. John River (SJR; open ocean-run) relative to Grand Lakes Stream (GLS; 200-year restricted ocean-run) or Sebago Lake (CAS; ~11,000 years landlocked) Atlantic salmon. However, lice density was similar between strains. Skin and fins had expectedly different transcriptomic profiles; however, notable differences were not observed between salmon strains. Variance in lice transcriptomes was minimally affected by attachment location even though lice strongly preferred fins relative to head or body. Attached lice did have different transcriptomic profiles on GLS relative to CAS or SJR. This study cumulatively identified a minimal host evolutionary component for sea lice attachment resistance, although lice behavior post-attachment appeared somewhat affected by strain. Non-uniform settlement distributions and tank-specific variability in lice attachment were observed across populations. Full article

(This article belongs to the Section Fish Pathology and Parasitology)

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15 pages, 1974 KB

Open AccessEditor’s ChoiceArticle

Comparing Year-Class Strength Indices from Longitudinal Analysis of Catch-at-Age Data with Those from Catch-Curve Regression: Application to Lake Huron Lake Trout

by Ji X. He and Charles P. Madenjian

Fishes 2025, 10(7), 332; https://doi.org/10.3390/fishes10070332 - 7 Jul 2025

Cited by 2 | Viewed by 2159

Abstract

Fish year-class strength (YCS) has been estimated via longitudinal analysis of catch-at-age data and via catch-curve regression, but no study has compared the two approaches. The objective of this study was to compare YCS estimates between the two approaches with application to the [...] Read more.

Fish year-class strength (YCS) has been estimated via longitudinal analysis of catch-at-age data and via catch-curve regression, but no study has compared the two approaches. The objective of this study was to compare YCS estimates between the two approaches with application to the lake trout (Salvelinus namaycush) population in the main basin of Lake Huron, one of the Laurentian Great Lakes of North America. YCSs were reconstructed for both hatchery-stocked and wild lake trout. Akaike information criterion (AIC) and Bayesian information criterion (BIC) were used to compare 14 linear mixed-effects models for longitudinal analysis of catch-at-age data, and three linear mixed-effects models for catch-curve regression. From the best models based on AIC or BIC comparisons, YCS estimates with year-class as a fixed effect were consistent with those estimated with year-class as a random effect. Estimated YCS patterns and trends were the same or similar between the longitudinal analysis and the catch-curve regression, indicating that both approaches provide robust estimates of YCS. Potential bias in using the approach of catch-curve regression could be caused by abrupt changes in adult mortality. It is also critical to recognize multiple recruitment origins for using the approach of longitudinal analysis of catch-at-age data. Full article

(This article belongs to the Section Biology and Ecology)

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15 pages, 2654 KB

Open AccessEditor’s ChoiceArticle

Presence and Potential Effect of Microplastics Associated with Anthropic Activity in Two Benthic Fishes Serranus scriba and Lithognathus mormyrus

by Amanda Cohen-Sánchez, Juan Alejandro Sanz, Montserrat Compa, Maria Magdalena Quetglas-Llabrés, Maria del Mar Ribas-Taberner, Lorenzo Gil, Silvia Tejada, Samuel Pinya and Antoni Sureda

Fishes 2025, 10(7), 323; https://doi.org/10.3390/fishes10070323 - 3 Jul 2025

Viewed by 2061

Abstract

Plastic pollution poses a massive problem to the environment, particularly seas and oceans. Microplastics (MPs) ingestion by marine species can generate many adverse effects, including causing oxidative stress. This study evaluated the effects of anthropic activity-related MP presence in two coastal fish species— [...] Read more.

Plastic pollution poses a massive problem to the environment, particularly seas and oceans. Microplastics (MPs) ingestion by marine species can generate many adverse effects, including causing oxidative stress. This study evaluated the effects of anthropic activity-related MP presence in two coastal fish species—Serranus scriba (more related to rocky bottoms) and Lithognathus mormyrus (more related to sandy bottoms)—in two areas of Mallorca Island (Western Mediterranean) with varying anthropic pressures with similar mixed rocky/sandy bottoms. A total of eight fish samples per species and per area (total n = 32), as well as three water samples (500 mL each) and three sediment samples per area, were collected and analyzed. The results showed that despite plastic presence in both areas, the area with higher tourism affluence was also the most polluted. Fourier transform infrared spectroscopy analysis confirmed that the majority of recovered polymers were polyethylene and polypropylene. The pattern of MPs presence was reflected in the biomarker analysis, which showed higher values of antioxidants, namely catalase (CAT) and superoxide dismutase (SOD); detoxification, namely glutathione s-transferase (GST); and inflammation, namely myeloperoxidase (MPO)—enzymes in the gastrointestinal tract of fish from the more polluted area. However, no statistical differences were found for malondialdehyde (MDA) as a marker of lipid peroxidation. As for differences between species, S. scriba presented a higher presence of MPs and measured biomarkers than in L. Mormyrus, suggesting higher exposure. In conclusion, these results showed that increased anthropic activity is associated with a higher presence of MPs which, in turn, induces an adaptative response in exposed fish. Moreover, species living in the same area could be differentially affected by MPs, which is probably associated with different behavioural and feeding habits. Full article

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

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13 pages, 593 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Sardine-Based Diet Mitigates Growth Depression at Low Temperatures in Juvenile Meagre (Argyrosomus regius, Asso 1801)

by Lav Bavčević, Slavica Čolak, Renata Barić, Siniša Petrović and Tin Klanjscek

Fishes 2025, 10(7), 314; https://doi.org/10.3390/fishes10070314 - 2 Jul 2025

Cited by 1 | Viewed by 2004

Abstract

Low seawater temperatures are expected to depress fish growth in aquaculture. However, recent evidence suggests diet composition may offer mitigation for some species. This study evaluated the impact of different diets on juvenile meagre (Argyrosomus regius) in cage farming at low [...] Read more.

Low seawater temperatures are expected to depress fish growth in aquaculture. However, recent evidence suggests diet composition may offer mitigation for some species. This study evaluated the impact of different diets on juvenile meagre (Argyrosomus regius) in cage farming at low seawater temperatures (average 15.19 °C), conditions known to typically suppress meagre growth. Three replicated groups of fish (initial weight ≈ 107 g) were fed for six months either sardines (group A) or commercial pellets (groups B/C, with group C moisturized). The results demonstrate that the nutritional profile of sardines effectively mitigates cold-induced growth reduction in meagre. While pellet-fed meagre experienced expected growth depression, sardine-fed meagre exhibited a doubled temperature growth coefficient (TGC) and an 80% higher final average weight than the pellet groups (A: 346.13 g, B: 194.44 g, C: 188.93 g). Full article

(This article belongs to the Special Issue Advancing Fish Nutrition Research for Sustainable Aquaculture)

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20 pages, 723 KB

Open AccessEditor’s ChoiceArticle

Changes in Subcellular Responses in the Digestive Gland of the Freshwater Mussel Unio crassus from a Historically Contaminated Environment

by Zoran Kiralj, Zrinka Dragun, Jasna Lajtner, Krešimira Trgovčić, Tatjana Mijošek Pavin, Bruno Bušić and Dušica Ivanković

Fishes 2025, 10(7), 317; https://doi.org/10.3390/fishes10070317 - 2 Jul 2025

Cited by 6 | Viewed by 1981

Abstract

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel Unio crassus from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic [...] Read more.

Utilizing a multi-biomarker approach, we assessed the potential adverse effects of pollutants on subcellular responses in the digestive gland of the freshwater mussel Unio crassus from a historically contaminated lowland section (KIZ) of the river Mrežnica compared to its less impacted upstream karstic section (REF) and their seasonality (spring vs. autumn). This approach accounted for the diverse modes of action of pollutants by including biomarkers of metal exposure (metallothioneins, MT), general stress (total cytosolic proteins, TP), antioxidative capacity (catalase, CAT; glutathione, GSH; glutathione-S-transferase, GST), oxidative damage (malondialdehyde, MDA), and neurotoxicity (acetylcholinesterase, AChE). Only in spring, MT concentrations were 15% higher at the REF site (4.38 ± 1.06 µg mg proteins⁻¹) compared to the KIZ site (3.69 ± 0.63 µg mg proteins⁻¹), likely related to elevated Cd bioaccumulation due to the karstic substrate. Regardless of the season, mussels from KIZ showed consistently lower TP and GSH, with significantly higher CAT, GST, and MDA levels, indicating elevated stress, activation of antioxidant defenses, and oxidative damage from chronic exposure to pro-oxidant pollutants, including metal(loid)s and organic contaminants (e.g., ibuprofen, nicotine). Compared to the REF site, AChE activity at the KIZ site was higher in late spring and lower in early autumn, indicating seasonal variability in AChE activity at the contamination-impacted location driven by fluctuating exposure to neurotoxicants, such as drugs and insecticides. Overall, biomarker responses indicated that mild historical pollution, reinforced by current low-capacity sources, has an observable impact on mussel health, posing long-term risks to sediment-dwelling aquatic organisms. Full article

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

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19 pages, 3260 KB

Open AccessEditor’s ChoiceArticle

Individual Variation in Movement Behavior of Stream-Resident Mediterranean Brown Trout (Salmo trutta Complex)

by Enric Aparicio, Rafel Rocaspana, Antoni Palau-Ibars, Neus Oromí, Dolors Vinyoles and Carles Alcaraz

Fishes 2025, 10(7), 308; https://doi.org/10.3390/fishes10070308 - 30 Jun 2025

Cited by 5 | Viewed by 2083

Abstract

Understanding individual movement patterns in stream-resident salmonids is critical for conservation and river management, particularly in Mediterranean streams characterized by high environmental variability. We tagged 997 Mediterranean brown trout (Salmo trutta complex) and conducted an 11-month mark–recapture study using Passive Integrated Transponder [...] Read more.

Understanding individual movement patterns in stream-resident salmonids is critical for conservation and river management, particularly in Mediterranean streams characterized by high environmental variability. We tagged 997 Mediterranean brown trout (Salmo trutta complex) and conducted an 11-month mark–recapture study using Passive Integrated Transponder (PIT) technology to assess movement behavior in the Flamisell River (Ebro Basin, northeastern Iberian Peninsula). Movements followed a leptokurtic distribution, with 81.8% of the individuals classified as sedentary (median movement = 24.9 m) and 18.2% as mobile (median movement = 376.2 m). Generalized linear models revealed distinct drivers of fish movement for each group. In sedentary trout, movement was mainly influenced by mesohabitat type, season, sex, and body size, with males and larger individuals moving farther. In mobile trout, mesohabitat type, density, and body size were key predictors. Movement patterns were repeatable over time, indicating consistent behavioral tendencies. These results support a bimodal movement strategy and highlight the importance of individual variation. Conservation planning should account for both sedentary and mobile groups to preserve functional and genetic connectivity and improve resilience of Mediterranean streams. 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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16 pages, 1657 KB

Open AccessEditor’s ChoiceArticle

Effect of the Inclusion of Natural Pigments on the Performance and Gene Expression of Immune Response and Oxidative Stress of Oreochromis niloticus Cultured in a Biofloc System

by Andres Elias Castro-Castellon, Maria del Carmen Monroy-Dosta, Aida Hamdan-Partida, Martha Patricia Hernandez-Vergara, Jorge Castro-Mejía, German Castro-Mejia, Arnulfo Misael Martinez-Meingüer and José Antonio Mata-Sotres

Fishes 2025, 10(6), 282; https://doi.org/10.3390/fishes10060282 - 8 Jun 2025

Cited by 1 | Viewed by 2292

Abstract

Tilapia (Oreochromis niloticus) is one of the most important species in aquaculture, so the optimization of its culture by using sustainable strategies is fundamental. The aim of this study was to evaluate the effects of incorporating natural pigments (carrot and beetroot [...] Read more.

Tilapia (Oreochromis niloticus) is one of the most important species in aquaculture, so the optimization of its culture by using sustainable strategies is fundamental. The aim of this study was to evaluate the effects of incorporating natural pigments (carrot and beetroot meal) as carbon sources in a biofloc system on the growth, immune response, and oxidative stress of O. niloticus. The experiment comprised four treatments: clear water as control (CT), biofloc with molasses (TBM), biofloc with carrot meal (TBC), and biofloc with beetroot meal (TBB). Results showed that biofloc helped to maintain optimal water quality and high survival rates, but specifically, TBC treatment achieved the highest growth rates and feed conversion ratio, along with elevated leukocyte counts, indicating improved health and immunity. Gene expression analysis revealed enhanced antioxidant activity (sod, gpx) and modulated immune responses (tnf-α, il-1β), particularly under thermal stress. Carrot meal emerged as an effective carbon source in biofloc systems, promoting growth, immune resilience, and oxidative stress resistance in tilapia, while beetroot meal improved pigmentation. These findings highlight the potential of natural pigments to enhance aquaculture sustainability and productivity. Full article

(This article belongs to the Special Issue Fish Hematology)

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14 pages, 4905 KB

Open AccessEditor’s ChoiceArticle

Effects of Micro- and Macroalgae-Supplemented Diets on Growth and Muscle Fibrillar Constitution of Gilthead Seabream, Sparus aurata L., in the Final On-Growing Phase

by María Dolores Ayala, Elena Chaves-Pozo, María Isabel Sáez, Francisco Javier Alarcón, Tomás Francisco Martínez and Marta Arizcun

Fishes 2025, 10(6), 262; https://doi.org/10.3390/fishes10060262 - 2 Jun 2025

Cited by 2 | Viewed by 2238

Abstract

The influence of algae in a final fattening diet for gilthead seabream, Sparus aurata, was studied in an 87 d feeding trial. Five groups were analysed (three tanks per group). In the first 38 days, one lot was fed with standard algae-free [...] Read more.

The influence of algae in a final fattening diet for gilthead seabream, Sparus aurata, was studied in an 87 d feeding trial. Five groups were analysed (three tanks per group). In the first 38 days, one lot was fed with standard algae-free feed (C1) and four batches were fed with an algae-free diet low in fishmeal (FM) and fish oil (FO) and rich in terrestrial vegetables (C2). Subsequently, the C2 diet was changed in three out of the four groups, two of them being fed a diet with a microalgae blend (10%) plus 2% macroalgae (Alaria esculenta), either in raw (C2-R) or hydrolysed (C2-H) form, and a third batch with a diet lacking FM and FO but supplemented with 10% microalgae and 7% algae oil (C2-O) for 49 days. Body length and weight, muscle parameters, and conversion index were analysed after 38 and 87 days. At day 38, no significant differences were observed in any parameter between C1 and C2, but at the end of the trial (day 87), C2 displayed the lowest weight gain and the worst conversion rate, whereas C2-R showed higher body weight, fibrillar hypertrophy, and better conversion rates than the other groups, and C2-H displayed higher hyperplasia values than the other groups. Full article

(This article belongs to the Special Issue Development of Low-Crop, Low-Fishmeal or Low-Fish Oil Feeds for Aquaculture)

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17 pages, 1604 KB

Open AccessEditor’s ChoiceArticle

Stable Isotope Analysis of Two Filter-Feeding Sharks in the Northwestern Pacific Ocean

by Chi-Ju Yu, Shoou-Jeng Joung, Hua-Hsun Hsu, Kwang-Ming Liu and Atsuko Yamaguchi

Fishes 2025, 10(6), 249; https://doi.org/10.3390/fishes10060249 - 26 May 2025

Cited by 2 | Viewed by 3563

Abstract

Understanding the feeding ecology and habitat use of vulnerable shark species is crucial for effective conservation. This study focuses on two large filter-feeding sharks, the megamouth shark (Megachasma pelagios) and whale shark (Rhincodon typus), in Northwestern Pacific waters. Stable [...] Read more.

Understanding the feeding ecology and habitat use of vulnerable shark species is crucial for effective conservation. This study focuses on two large filter-feeding sharks, the megamouth shark (Megachasma pelagios) and whale shark (Rhincodon typus), in Northwestern Pacific waters. Stable isotope analysis (δ¹³C and δ¹⁵N) was conducted on white muscle samples (n = 91) of M. pelagios and fin clips (n = 90) of R. typus, collected via large-mesh drift nets and set nets in Taiwanese waters. In this study, we investigated feeding strategies, ontogenetic dietary shifts, habitat use, and isotopic niche variation in both species. For R. typus, the observed positive correlation between δ¹³C and δ¹⁵N supports the previously proposed active suction filter feeding, as well as implying both a diet with an increasing proportion of higher trophic level prey and an ontogenetic shift. In contrast, M. pelagios displayed a negative correlation, consistent with a previous study associating such patterns with primary or secondary consumers, further aligning with its reported planktonic prey dominance. Both species had increasing δ¹³C with growth, signifying a shift to nutrient-rich habitats. Only R. typus exhibited ontogenetic diet changes (δ¹⁵N). SIBER (Stable Isotope Bayesian Ellipses in R) analysis revealed distinct feeding strategies and habitat use between the two species, potential sexual segregation, and wider isotopic niche widths for males in both species. The findings underscore the importance of considering species-specific behaviors and sex-based differences in conservation strategies. Full article

(This article belongs to the Section Biology and Ecology)

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23 pages, 11176 KB

Open AccessEditor’s ChoiceArticle

Multi-Omics Investigation of Fatty Acid Content Variations in Common Carp (Cyprinus carpio) Muscle: Integrating Genome, Transcriptome, and Lipid Profiling Data

by Kaikuo Wang, Qi Wang, Yingjie Chen, Yiming Cao, Ran Zhao, Shuangting Yu, Xiaoqing Sun, Yan Zhang and Jiongtang Li

Fishes 2025, 10(5), 234; https://doi.org/10.3390/fishes10050234 - 16 May 2025

Cited by 3 | Viewed by 2322

Abstract

Fatty acids (FAs), especially the polyunsaturated fatty acids (PUFAs), play pivotal roles in growth and development. Fish possess a remarkable ability to synthesize PUFAs, rendering them a crucial and significant source of these essential FAs for human consumption. Despite extensive research on the [...] Read more.

Fatty acids (FAs), especially the polyunsaturated fatty acids (PUFAs), play pivotal roles in growth and development. Fish possess a remarkable ability to synthesize PUFAs, rendering them a crucial and significant source of these essential FAs for human consumption. Despite extensive research on the metabolic processes of FAs, the primary processes underlying FA content variation and corresponding regulatory mechanisms remain largely unexplored. We quantified the muscular FA profiles of 304 common carp samples. High variation in muscle FA content among samples was observed, with the coefficients of variation ranging from 0.36 to 0.92. With genome-wide association studies (GWAS), we identified 1410 SNPs significantly associated with the FA content. The genetic variation at genes participating in oxidation, ubiquitination, and transcriptional factors was associated with the content of multiple FAs, while few variants were observed in the FA-synthesis genes. For the total PUFA (TPUFA) content, transcriptome analysis of groups with the highest and lowest TPUFA content identified 715 differentially expressed genes (DEGs), including genes involved in oxidation and ubiquitination. Using multiple genomic selection programs with the associated SNPs for FA content, we obtained high and positive correlations ranging from 0.65 to 0.92 between the real FA contents and estimated breeding values. These findings manifested the major-effect processes governing the differences in muscular FA content and their regulatory mechanisms. The optimal genomic selection programs provide novel and feasible perspectives to enhance FA content in common carp. Full article

(This article belongs to the Special Issue Molecular Design Breeding in Aquaculture)

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13 pages, 704 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Dietary Lauric Acid Supplementation Positively Affects Growth Performance, Oxidative and Immune Status of European Seabass Juveniles

by Filipa Fontinha, Nicole Martins, Rui Magalhães, Helena Peres and Aires Oliva-Teles

Fishes 2025, 10(5), 190; https://doi.org/10.3390/fishes10050190 - 22 Apr 2025

Cited by 7 | Viewed by 4182

Abstract

Lauric acid (LA), a medium-chain fatty acid (C12), can promote growth performance and decrease oxidative damage and lipid deposition in animals. This study aimed to evaluate the effect of dietary supplementation of lauric acid as a functional ingredient on European seabass juveniles’ growth [...] Read more.

Lauric acid (LA), a medium-chain fatty acid (C12), can promote growth performance and decrease oxidative damage and lipid deposition in animals. This study aimed to evaluate the effect of dietary supplementation of lauric acid as a functional ingredient on European seabass juveniles’ growth performance and intestine antioxidant and immunological status. For this purpose, four practical diets were formulated to be isoproteic and isolipidic, including 0, 0.5, 1, and 2% of LA, and fed to triplicate groups of European seabass juveniles (~12.7 g) for 61 days. Dietary LA supplementation did not affect growth performance, feed utilization, or whole-body composition, but feed intake increased at a concentration-dependent level. However, the plasmatic triglyceride content was increased at the higher level of LA supplementation. In the intestine, catalase and glutathione reductase activities and lipid peroxidation levels were lower in fish fed the 1% LA diet than in the control group. The hepatic LPO level was higher in fish fed 0.5% LA than in the control group. Fish fed the 1% LA diet presented lower intestinal expressions of caspase 3, tumor necrosis factor-alpha, interleukins 10, 6, and 1-β, and a lower plasma white blood cell number. Overall, up to 2% dietary supplementation of lauric acid as a functional ingredient showed a trend to improve European sea bass juveniles’ growth performance without affecting feed utilization. Moreover, 1% dietary inclusion of LA reduced intestinal lipid peroxidation and downregulated pro-inflammatory and anti-inflammatory genes, thus enhancing the intestine’s homeostatic status. Full article

(This article belongs to the Section Nutrition and Feeding)

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13 pages, 667 KB

Open AccessEditor’s ChoiceArticle

A Comparison of White Muscle Quality in Grass Carp Ctenopharyngodon idellus Fed with Commercial Feeds and Barley Malt

by Chongjiang Hu, Zheng Huang, Hongkang Liu, Dingrui Mo, Peng Fu, Haiyan Guo, Wei Jiang, Yong Xie and Yongjun Chen

Fishes 2025, 10(4), 185; https://doi.org/10.3390/fishes10040185 - 18 Apr 2025

Cited by 4 | Viewed by 2593

Abstract

This study was the first report regarding the application of barley malt (BM) for diets of aquaculture species. Triplicate groups of grass carp Ctenopharyngodon idellus with an initial size of about 1.2 kg were selected and fed with either BM or commercial feed [...] Read more.

This study was the first report regarding the application of barley malt (BM) for diets of aquaculture species. Triplicate groups of grass carp Ctenopharyngodon idellus with an initial size of about 1.2 kg were selected and fed with either BM or commercial feed (CF) to apparent satiation for 8 weeks in outdoor ponds connected with a flow-through aquaculture system. The results showed that the final body weight (1651 g) was lower in the BM fish than in the CF fish (1791 g). The edible part was lower in the BM fish than in the CF fish as indicated by the viscerosomatic index. Except for ash levels, which were lower in the fillet of the BM fish than for that of the CF fish, moisture, protein, and lipid levels were not impacted by the application of BM. Water-holding capacity indicators (drop loss, frozen exudation rate, and cooking loss) of grass carp muscle were not relevant to dietary modifications. Hematoxylin-eosin (HE) staining showed that the diameter of the myofibers was decreased while density was increased in response to the application of BM, which contributed to the improvement in textural properties (hardness, gumminess, and chewiness) in the muscle of the BM fish as compared to the CF fish. Glutamic acid level was highest, followed by aspartic acid, lysine, leucine, alanine, and arginine in grass carp muscle. Except three amino acids (proline, phenylalanine, and histidine), the amounts of the other 15 amino acids, essential amino acids, semi-essential amino acids, nonessential amino acids, and delicious amino acids were not impacted by different treatments, suggesting that the application of BM had a minor effect on the amino acid composition of grass carp muscle. Oleic acid (C18:1n-9), linoleic acid (C18:2n-6), and palmitic acid (C16:0) were the most abundant fatty acids in grass carp muscle. The amounts of poly-unsaturated fatty acid (PUFA) in the muscle decreased in response to the application of BM as the diet of grass carp, and n-6 PUFAs (C18:2n-6 and C20:2n-6) rather than n-3 PUFAs accounted for this change, which is beneficial for human health. In conclusion, the application of BM had minor impacts on the proximate composition and amino acid composition but improved textural properties and decreased n-6 PUFAs in the fillet of grass carp. Full article

(This article belongs to the Special Issue Growth, Metabolism, and Flesh Quality in Aquaculture Nutrition)

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18 pages, 2154 KB

Open AccessEditor’s ChoiceArticle

Reconstruction of Recreational Catch and Multi-Fisheries Stock Assessment of Hairtail (Trichiurus lepturus) in Korean Waters Under a Data-Limited Situation

by Sang Chul Yoon, Moo-Jin Kim, Heejoong Kang and Min-Je Choi

Fishes 2025, 10(4), 166; https://doi.org/10.3390/fishes10040166 - 8 Apr 2025

Cited by 5 | Viewed by 3373

Abstract

Accurate catch data are essential for effective fisheries management. This study reconstructs the historical recreational catch of hairtail (Trichiurus lepturus) in Korean waters by incorporating unreported catches to improve stock assessment accuracy. Using a Bayesian state-space surplus production model, we conducted [...] Read more.

Accurate catch data are essential for effective fisheries management. This study reconstructs the historical recreational catch of hairtail (Trichiurus lepturus) in Korean waters by incorporating unreported catches to improve stock assessment accuracy. Using a Bayesian state-space surplus production model, we conducted a multi-fishery stock assessment by integrating abundance indices from eight major fisheries. The multigear mean standardization (MGMS) method was applied to derive standardized CPUE indices for each fishery, providing a more comprehensive evaluation of stock trends. The results indicate that excluding recreational catches and multiple CPUE indices may lead to biased stock assessments of hairtail in Korean waters. Models using an integrated CPUE index (SMSC) yielded higher MSY and biomass estimates, suggesting a more optimistic stock condition, whereas fishery-specific CPUE models (MSC) provided more precautionary estimates. The Kobe plot analysis indicates recent stock recovery, but continued monitoring and adaptive management are required to ensure long-term sustainability. This study highlights the importance of integrating recreational catch data and multi-fishery approaches in stock assessments, particularly under data-limited conditions, to enhance resource management and policy decision-making. 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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20 pages, 2383 KB

Open AccessEditor’s ChoiceArticle

Age, Growth, and Mortality of the Common Pandora (Pagellus erythrinus, L. 1758) in the Central Aegean Sea: Insights into Population Dynamics

by Alexandros Theocharis, Sofia Vardali and Dimitris Klaoudatos

Fishes 2025, 10(4), 160; https://doi.org/10.3390/fishes10040160 - 4 Apr 2025

Cited by 7 | Viewed by 3142

Abstract

This study investigates the age, growth, and mortality of the common pandora (Pagellus erythrinus) in the Central Aegean Sea, providing critical insights into its population dynamics and sustainability. A total of 589 specimens were analyzed, identifying nine age cohorts with mean [...] Read more.

This study investigates the age, growth, and mortality of the common pandora (Pagellus erythrinus) in the Central Aegean Sea, providing critical insights into its population dynamics and sustainability. A total of 589 specimens were analyzed, identifying nine age cohorts with mean total lengths ranging from 13.18 cm to 32.94 cm. Growth parameters, estimated using the von Bertalanffy growth model, yielded an asymptotic length (L∞) of 39.53 cm and a growth coefficient (k) of 0.16 year⁻¹, indicating moderate growth rates. The population exhibited non-isomorphic growth (b = 2.49, R² = 98.4), suggesting slower weight gain relative to length. Mortality estimates indicated natural mortality (M) at 0.321 year⁻¹, total mortality (Z) at 0.52 year⁻¹, and fishing mortality (F) at 0.2 year⁻¹, resulting in an exploitation rate (E) of 0.38. The fishing mortality at maximum sustainable yield (FMSY) was estimated at 0.33, with an exploitation rate at MSY (EMSY) of 0.51, suggesting that the population is currently harvested sustainably but close to the threshold of overexploitation. These findings provide essential reference points for fisheries management and highlight the need for continuous monitoring to ensure the long-term sustainability of P. erythrinus in Greek waters. Full article

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17 pages, 2047 KB

Open AccessEditor’s ChoiceArticle

You Are What You Eat: California Sea Cucumbers Become “Fishier” After Integrated Multi-Trophic Aquaculture with Chinook Salmon

by Emaline M. Montgomery, Barb L. Cannon, Miki Nomura, Rodrigo B. Leme, Ian P. Forster and Christopher M. Pearce

Fishes 2025, 10(4), 154; https://doi.org/10.3390/fishes10040154 - 1 Apr 2025

Viewed by 2487

Abstract

Recent interest in integrated multi-trophic aquaculture (IMTA) as an ecologically-sustainable and climate-conscious aquaculture system has resulted in testing different species partnerships and configurations in anticipation of industrialization. Deposit feeders like the California sea cucumber (Apostichopus californicus) have been suggested as ideal [...] Read more.

Recent interest in integrated multi-trophic aquaculture (IMTA) as an ecologically-sustainable and climate-conscious aquaculture system has resulted in testing different species partnerships and configurations in anticipation of industrialization. Deposit feeders like the California sea cucumber (Apostichopus californicus) have been suggested as ideal partners for IMTA with finfish, due to their ability to consume fish waste as well as their passive nature. However, the nutritional impacts of feeding on fish waste in IMTA have not yet been established for this species. The present study tested the effect of 3 months of inclusion in IMTA with Chinook salmon (Oncorhynchus tshawytscha) on the fatty-acid and nitrogenous-metabolite profiles of California sea cucumbers. The fatty-acid profiles of IMTA sea cucumbers showed significant changes from wild reference individuals, while few differences were detected in amino acids and other nitrogenous metabolites. Sea cucumbers housed directly in cages with salmon showed distinct shifts in their fatty-acid profiles toward higher levels of MUFAs and lower levels of SFAs, while PUFA concentrations remained the same. Sea cucumbers included in IMTA with finfish may be even more healthful for humans due to the accumulation of certain unsaturated fatty acids in their tissues not seen in wild reference individuals. Full article

(This article belongs to the Special Issue Advances in Integrated Multi-Trophic Aquaculture)

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19 pages, 1068 KB

Open AccessEditor’s ChoiceArticle

Impact of Dietary Glutamate on Growth Performance and Flesh Quality of Largemouth Bass

by Bo Zhao, Ju Zhao, Haifeng Liu, Hailong Zhang, Hongying Shan, Jiali Zong, Quanquan Cao and Jun Jiang

Fishes 2025, 10(4), 151; https://doi.org/10.3390/fishes10040151 - 31 Mar 2025

Cited by 11 | Viewed by 3259

Abstract

The influence of dietary glutamate (Glu) was evaluated in a 56-day feeding trial on the growth performance and flesh quality of largemouth bass (Micropterus salmoides). A total of 1170 fish (average body weight 24.05 ± 0.22 g) were randomly allocated into [...] Read more.

The influence of dietary glutamate (Glu) was evaluated in a 56-day feeding trial on the growth performance and flesh quality of largemouth bass (Micropterus salmoides). A total of 1170 fish (average body weight 24.05 ± 0.22 g) were randomly allocated into six groups, with three replicates per group. They were fed diets containing Glu in levels of 11.40% (G1), 11.88% (G2), 12.53% (G3), 13.27% (G4), 14.33% (G5), and 15.62% (G6). We found that, over a 56-day feeding period, the final body weight (FBW) of largemouth bass was about 4–5 times the IBW. The FBW, percent weight gain (PWG), specific growth rate (SGR), feed efficiency (FE), and protein efficiency ratio (PER) initially increased and then decreased with elevating dietary Glu levels. Likewise, protein content, lipid content, apparent digestibility coefficient of dry matter (ADC_D), and apparent digestibility coefficient of protein (ADC_P) followed a similar pattern. Supplementation with Glu significantly improved the hepatosomatic index (HSI), viscerosomatic index (VSI), and relative gut length (RGL). Moreover, dietary Glu augmentation noticeably enhanced flesh composition such as muscle protein, ash, lipid, amino acid contents, and polyunsaturated fatty acids (PUFAs). Furthermore, dietary Glu supplementation enhanced muscle physicochemical quality (such as drip loss and pH), textural properties (adhesiveness and cohesiveness), and biochemical indices such as total protein (TP) and salt-soluble protein, while decreasing muscle cathepsin B (CtsB) and lactate dehydrogenase (LD) contents, thereby improving flesh quality. In conclusion, these findings suggest that Glu plays a crucial role in enhancing both growth performance and muscle quality in largemouth bass. The optimal dietary requirement for juvenile largemouth bass was estimated to be approximately 125.1 g/kg of diet based on SGR analysis. Full article

(This article belongs to the Section Nutrition and Feeding)

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15 pages, 649 KB

Open AccessEditor’s ChoiceArticle

Exploring Nationwide Oyster Aquaculture Data: An Index to Compare Regulatory, Production, and Economic Attributes of Oyster Aquaculture Among U.S. States and Regions

by Anthony R. Lima

Fishes 2025, 10(4), 138; https://doi.org/10.3390/fishes10040138 - 21 Mar 2025

Cited by 2 | Viewed by 5171

Abstract

Wild oyster reefs have been harvested for centuries and continue to face anthropogenic pressures, including climate change, pollution, and habitat reduction. Oyster aquaculture has grown to supplement depleted wild stocks and strengthen local economies, but development has not occurred at the same rate [...] Read more.

Wild oyster reefs have been harvested for centuries and continue to face anthropogenic pressures, including climate change, pollution, and habitat reduction. Oyster aquaculture has grown to supplement depleted wild stocks and strengthen local economies, but development has not occurred at the same rate across all regions. Across the United States, states have a variety of political and cultural influences that impact oyster aquaculture policy, constraining the ability to make direct comparisons among locations that could enhance aquaculture expansion in slower-to-develop states and regions. This research developed a four-part index to compare regulatory, production, and economic attributes of oyster aquaculture among 23 coastal states. The final index score—a summation of the four individual index components—provides a broad integrated view of oyster aquaculture across the U.S. The results indicate that coastal states in the U.S. Mid-Atlantic and New England regions have the greatest number of resource and policy attributes in place to support oyster aquaculture, whereas coastal states in the Gulf of Mexico and Western Pacific region have relatively less in the way of aquaculture-supporting structures. As the oyster aquaculture industry continues to grow in the U.S., results from this study can help organizations involved in oyster aquaculture to make informed decisions to expand permitting, leasing, and production systems, following the model from states who have been active in oyster aquaculture for decades. Mindful and cautious improvements can facilitate sustainable sources of seafood and stable income generation for coastal communities while reducing pressures on wild stocks. Full article

(This article belongs to the Special Issue Fisheries Monitoring and Management)

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26 pages, 4940 KB

Open AccessEditor’s ChoiceArticle

Integration of Gill and Intestinal Osmoregulatory Functions to Assess the Smoltification Window in Atlantic Salmon

by Jonás I. Silva-Marrero, Floriana Lai, Sigurd O. Handeland, Cindy Pedrosa, Virginie Gelebart, Pablo Balseiro, Juan Fuentes, Ivar Rønnestad and Ana S. Gomes

Fishes 2025, 10(3), 119; https://doi.org/10.3390/fishes10030119 - 8 Mar 2025

Cited by 8 | Viewed by 4832

Abstract

The transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (LL) and winter [...] Read more.

The transfer time of Atlantic salmon smolts from freshwater to seawater remains a challenge in aquaculture, with the “smolt window” referring to the optimal timeframe for seawater readiness. Our study monitored Atlantic salmon osmoregulatory adaptations during smoltification under continuous light (LL) and winter signal regime (6 weeks LD 12:12) followed by 6 or 8 weeks of constant light. Fish were subsequently reared in seawater for 8 weeks and subjected to a stress event of cyclic hypoxia at the conclusion of the trial. Significant differences in growth trajectories were observed between the LL and LD groups, with fish receiving the winter signal showing compensatory growth after seawater transfer. Gill Na⁺/K⁺-ATPase (NKA) activity, plasma ions, glucose, and cortisol levels confirmed the importance of the winter signal for seawater adaptation. Molecular markers, including nka isoforms, Na⁺-K⁺-2Cl⁻ cotransporter (nkcc), cystic fibrosis transmembrane conductance regulator (cftr), and Na⁺/HCO₃⁻ cotransporter (nbc), showed distinct temporal expression patterns, particularly in gills and midgut. Notably, the LD group with delayed seawater transfer exhibited enhanced growth and improved hypo-osmoregulatory capacity. These findings underscore the advantages of a winter signal in smoltification and suggest that delaying seawater transfer for up to 8 weeks could be beneficial. Full article

(This article belongs to the Special Issue Rhythms in Marine Fish and Invertebrates)

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22 pages, 1530 KB

Open AccessEditor’s ChoiceArticle

Investigation of Plasticity in Morphology, Organ Traits and Nutritional Composition in Chinese Soft-Shelled Turtle (Pelodiscus sinensis) Under Different Culturing Modes

by Ming Qi, Yang Wang, Liangliang Hu, Guangmei Chen, Tianlun Zheng, Xueyan Ding, Yijiang Bei, Jianjun Tang, Wenjun Ma and Xin Chen

Fishes 2025, 10(3), 89; https://doi.org/10.3390/fishes10030089 - 20 Feb 2025

Cited by 6 | Viewed by 4554

Abstract

The Chinese soft-shelled turtle (Pelodiscus sinensis) is an aquatic reptile prized for its nutritional and health benefits. Given its adaptability to various culturing modes including the greenhouse, pond and rice culturing modes, we conducted a comparative analysis of the morphology, organ [...] Read more.

The Chinese soft-shelled turtle (Pelodiscus sinensis) is an aquatic reptile prized for its nutritional and health benefits. Given its adaptability to various culturing modes including the greenhouse, pond and rice culturing modes, we conducted a comparative analysis of the morphology, organ trait and nutritional composition of turtles cultured in three culturing modes. This study investigated the plasticity of morphology and physiology, as well as the variations in nutritional composition across varying culturing modes. The results demonstrated that after approximately 120 days of cultivation, significant changes were observed in the morphology, physiology and nutritional composition of turtles from each culturing mode. In terms of morphology, rice turtles exhibited an arched shell shape, broad plastron, elongated limbs, narrow interocular distance and slender head and neck. Pond turtles displayed similar morphological characteristics to rice turtles, with the additional features of a flattened body shape and narrower plastron. Greenhouse turtles presented a flattened shell shape, narrow plastron, shortened limbs, wider interocular distance and stocky head and neck. Regarding the organ characteristics, the specific weights of liver, viscera, internal fat lumps and condition factors were significantly higher in greenhouse turtles compared to rice turtles and pond turtles (p < 0.05). Conversely, the specific weights of the back carapace, calipash and edible part were significantly lower than those in rice turtles and pond turtles (p < 0.05). Nutritional analysis revealed that crude protein, total amino acid, essential amino acid, flavor amino acid, pharmacodynamic amino acid, collagen and EPA+DHA contents were significantly higher in rice turtles and pond turtles than greenhouse turtles (p < 0.05). However, crude fat and unsaturated fatty acid contents were significantly higher in greenhouse turtles than in rice turtles and pond turtles (p < 0.05). In summary, Chinese soft-shelled turtles exhibited significant morphological and organ plasticity in response to different culturing modes. While the rice and pond culturing modes could enhance the nutritional quality of turtles to some extent, the impact of commercial feed on fatty acid profiles must be carefully considered. Full article

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23 pages, 5624 KB

Open AccessEditor’s ChoiceArticle

Heat Shock Factors in the European Eel: Gene Characterization and Expression Response to Different Environmental Conditions and to Induced Sexual Maturation

by Leonor Ferrão, Luz Pérez, Juan F. Asturiano and Marina Morini

Fishes 2025, 10(2), 73; https://doi.org/10.3390/fishes10020073 - 12 Feb 2025

Cited by 1 | Viewed by 2424

Abstract

Heat shock factors (HSFs) are transcription factors that regulate responses to environmental changes and play roles in physiological mechanisms like spermatogenesis. This study analyzed the HSF gene family and their expression profiles in the European eel under different environmental conditions and during testis [...] Read more.

Heat shock factors (HSFs) are transcription factors that regulate responses to environmental changes and play roles in physiological mechanisms like spermatogenesis. This study analyzed the HSF gene family and their expression profiles in the European eel under different environmental conditions and during testis maturation. Six HSF genes were identified in the studied vertebrates, in which the eel presents two HSF1 paralogs (HSF1a and HSF1b), likely resulting from the teleost whole-genome duplication event, while only one paralog is present for the other HSF (HSF2, HSF4, and HSF5). All five HSF genes were highly expressed in the testis, but some were also detected in the brain, intestine, and gills. Our findings showed that HSF1 changed their expression in response to different temperature and salinity conditions, suggesting that these may support males in perceiving the temperature and salinity changes possibly found during reproductive migration. During hCGrec-induced spermatogenesis, HSF genes presented a decreasing expression profile throughout testis maturation (with significant differences in HSF1a and HSF4), except HSF5, which showed the highest levels after 4 weeks of hormonal treatment. Our study indicates that HSF genes are potentially implicated in the response to environmental changes perception and during gonadal maturation. Full article

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23 pages, 3009 KB

Open AccessEditor’s ChoiceReview

Advancing Fisheries Research and Management with Computer Vision: A Survey of Recent Developments and Pending Challenges

by Jesse Eickholt, Jonathan Gregory and Kavya Vemuri

Fishes 2025, 10(2), 74; https://doi.org/10.3390/fishes10020074 - 12 Feb 2025

Cited by 6 | Viewed by 4348

Abstract

The field of computer vision has progressed rapidly over the past ten years, with noticeable improvements in techniques to detect, locate, and classify objects. Concurrent with these advances, improved accessibility through machine learning software libraries has sparked investigations of applications across multiple domains. [...] Read more.

The field of computer vision has progressed rapidly over the past ten years, with noticeable improvements in techniques to detect, locate, and classify objects. Concurrent with these advances, improved accessibility through machine learning software libraries has sparked investigations of applications across multiple domains. In the areas of fisheries research and management, efforts have centered on the localization of fish and classification by species, as such tools can estimate the health, size, and movement of fish populations. To aid in the interpretation of computer vision for fisheries research management tasks, a survey of the recent literature was conducted. In contrast to prior reviews, this survey focuses on employed evaluation metrics and datasets as well as the challenges associated with applying machine learning to a fisheries research and management context. Misalignment between applications and commonly used evaluation metrics and datasets mischaracterizes the efficacy of emerging computer vision techniques for fisheries research and management tasks. Aqueous, turbid, and variable lighted deployment settings further complicate the use of computer vision and generalizability of the reported results. Informed by these inherent challenges, culling surveillance data, exploratory data collection in remote settings, and selective passage and traps are presented as opportunities for future research. Full article

(This article belongs to the Section Fishery Economics, Policy, and Management)

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25 pages, 2423 KB

Open AccessEditor’s ChoiceArticle

Molecular Immune Responses of Ruditapes decussatus to Vibrio Infection at Different Temperatures: Expression of Key Genes and Resilience-Associated Single Nucleotide Polymorphisms

by Dimitrios K. Papadopoulos, Ioannis A. Giantsis, Athanasios Lattos, Konstantina Bitchava and Basile Michaelidis

Fishes 2025, 10(2), 72; https://doi.org/10.3390/fishes10020072 - 11 Feb 2025

Cited by 5 | Viewed by 2444

Abstract

The impact of pathogenic Vibrio on bivalves is expected to be aggravated by global warming, posing a growing threat to aquaculture. Clam production has been particularly vulnerable, with significant losses attributed to the lack of pathogen-resistant strains. In this study, the mantle cavity [...] Read more.

The impact of pathogenic Vibrio on bivalves is expected to be aggravated by global warming, posing a growing threat to aquaculture. Clam production has been particularly vulnerable, with significant losses attributed to the lack of pathogen-resistant strains. In this study, the mantle cavity of the grooved carpet shell clam Ruditapes decussatus (Linnaeus, 1758) was injected with Vibrio splendidus at 18 °C, 22 °C, and 24 °C and the transcription of the phagelysozyme, Cu-Zn superoxide dismutase (Cu-Zn sod), tumor necrosis factor receptor associated factor 6 (traf6), inhibitor of NF-κB (IκB), and Fas-associated protein with death domain (fadd) genes were assessed during a 20-day period. Additionally, the coding sequences of lysozyme, fadd, and IκB in Ruditapes decussatus were characterized for the first time, and SNPs were identified. Some SNPs showed significantly different distributions between infection-resistant and infection-susceptible individuals. Infected clams experienced increased mortality at elevated temperatures. Lysozyme mRNA was upregulated in infected groups across all temperatures. The sustained increase on day 20, coinciding with elevated traf6 mRNA, suggests a prolonged activation of the immune response. Cu-Zn sod transcription at 18 °C and 22 °C peaked on day 7 and returned to control levels by day 20, indicating an effective immune response, while at 24 °C, infected animals showed a continuously increased transcription. IκΒ and traf6 transcription, reflecting NF-κB pathway activity, varied with temperature and showed transient stimulation at higher temperatures. The pattern of fadd expression indicated a late induction of apoptosis, particularly at 18 °C and 24 °C. Overall, this study illustrates the involvement of five key genes in host–pathogen interactions and identifies potential markers for selection for Vibrio resistance in Ruditapes decussatus. However, given the weak correlation observed, further research is needed on the link between these polymorphisms and pathogen resilience. Full article

(This article belongs to the Special Issue Prevention and Control of Aquatic Animal Diseases)

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13 pages, 5211 KB

Open AccessEditor’s ChoiceArticle

Preferred and Optimal Swimming Speeds in Rainbow Trout (Oncorhynchus mykiss) at Three Temperatures

by Ólavur av Fløtum Mittún, Morten Bo Søndergaard Svendsen, Lars Emil Juel Andersen, Heiðrikur Bergsson and John Fleng Steffensen

Fishes 2025, 10(2), 64; https://doi.org/10.3390/fishes10020064 - 4 Feb 2025

Cited by 2 | Viewed by 3900

Abstract

Sustained exercise in aquaculture is known to improve the health and growth of finfish. Implementing exercise regimes has become an increasing focus in aquaculture practice. This study examined the relationship between the preferred swimming speed (U_pref) and the optimal swimming speed [...] Read more.

Sustained exercise in aquaculture is known to improve the health and growth of finfish. Implementing exercise regimes has become an increasing focus in aquaculture practice. This study examined the relationship between the preferred swimming speed (U_pref) and the optimal swimming speed (U_opt) in rainbow trout (Oncorhynchus mykiss) under non-migratory conditions typical of aquaculture environments. Using a circular raceway, rainbow trout were allowed to swim voluntarily to determine U_pref. U_opt was measured using a forced-swimming test in a swim tunnel respirometer. Experiments were conducted at three temperatures (10 °C, 15 °C, and 20 °C). The results revealed a significant difference between U_pref (1.18 ± 0.14, 1.17 ± 0.19, and 1.24 ± 0.15 BL s⁻¹, respectively) and U_opt (1.4 ± 0.19, 1.5 ± 0.15, and 1.6 ± 0.24 BL s⁻¹, respectively) across all temperatures. Aerobic scope was greatest at 15 °C (3.8), consistent with the species’ thermal range. Notably, swimming at U_pref required 18–22% less energy than U_opt, suggesting that U_pref is more suitable for aquaculture systems. This study introduces a minimally invasive and stress-free method for determining U_pref and provides insights that can optimize flow regimes in aquaculture tanks, improving both energy efficiency and fish welfare. Full article

(This article belongs to the Special Issue Technology for Fish and Fishery Monitoring)

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16 pages, 1240 KB

Open AccessEditor’s ChoiceArticle

Stock Structure of the Gulf Hake Urophycis cirrata (Teleostei: Phycidae) in South-Western Atlantic Using Otolith Shape and Elemental Analyses

by César Santificetur, Carmen Lúcia Del Bianco Rossi-Wongtschowski, André Ruperti, Agostinho Almeida, Edgar Pinto and Alberto Teodorico Correia

Fishes 2025, 10(2), 63; https://doi.org/10.3390/fishes10020063 - 4 Feb 2025

Cited by 3 | Viewed by 2064

Abstract

Urophycis cirrata is an important demersal fish species targeted by Brazilian industrial fisheries. With high exploitation rates, its stock(s) is(are) currently deemed fully exploited or overexploited. While basic ecological information, such as length at first maturity, exists, knowledge of its population structure is limited. [...] Read more.

Urophycis cirrata is an important demersal fish species targeted by Brazilian industrial fisheries. With high exploitation rates, its stock(s) is(are) currently deemed fully exploited or overexploited. While basic ecological information, such as length at first maturity, exists, knowledge of its population structure is limited. A sub-sample of 90 sagittal otoliths of U. cirrata juveniles (300–411 mm total length) collected during the Program for Assessment of the Sustainable Potential of Living Resources in the Exclusive Economic Zone (REVIZEE) in 2001/2002 was analyzed. Samples came from the outer continental shelf and upper slope of the southeast-south Brazilian coast, divided into three regions: northern (Cabo São Tomé to São Sebastião), central (São Sebastião to Cabo Santa Marta Grande), and southern (Cabo Santa Marta Grande to Chuí). Otolith shape (elliptic Fourier descriptors) and elemental (element:Ca) signatures were examined using univariate (ANOVA, Tukey) and multivariate (MANOVA, LDFA) statistical methods. An overall reclassification success rate of 86% was achieved using both signatures. However, individuals from the three regions were not fully separable, indicating a single, albeit not homogeneous, population unit for fisheries management. As fish stocks are dynamic, contemporary studies should be conducted to verify whether this population structure persists. Full article

(This article belongs to the Section Biology and Ecology)

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17 pages, 3447 KB

Open AccessFeature PaperEditor’s ChoiceArticle

Using Nearshore Fish Communities to Evaluate Eutrophication Impact in Temperate Estuaries

by Mark D. Saunders, Nathanael Bergbusch, Kyle M. Knysh, Leah P. MacIntyre, Christina C. Pater, Michael R. S. Coffin, Monica Boudreau, Michael R. van den Heuvel and Simon C. Courtenay

Fishes 2025, 10(2), 55; https://doi.org/10.3390/fishes10020055 - 29 Jan 2025

Viewed by 2416

Abstract

Using fishes as indicators of estuarine degradation is informative in long-term monitoring programs. Beach seine hauls were used in four estuaries that differed in their trophic and tidal status. The study found that inner, middle, and outer estuarine nearshore fish communities differed significantly [...] Read more.

Using fishes as indicators of estuarine degradation is informative in long-term monitoring programs. Beach seine hauls were used in four estuaries that differed in their trophic and tidal status. The study found that inner, middle, and outer estuarine nearshore fish communities differed significantly at from all estuaries, for all sampling times. To reduce the effects of within-estuary variability, between-estuary differences were examined separately for inner, middle, and outer estuarine areas. These analyses revealed differences in north-south and trophic status in communities between estuaries. The north-south differences were characterized by more benthic fishes, such as mummichogs and fourspine stickleback in the microtidal northern estuaries and proportionally more pelagic fishes, such as Atlantic silversides and river herring in the mesotidal estuaries. In both multivariate and univariate analyses, mummichogs were also featured as being most abundant in the more eutrophic estuaries. The distance-based redundancy analysis showed that bare sediment coverage was the strongest correlate of the north-south differences, while the Ulva to Zostera plant gradient was more influential in predicting eutrophication impacts on communities in the inner and middle estuary. Full article

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

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18 pages, 4001 KB

Open AccessEditor’s ChoiceArticle

Broadband Characteristics of Target Strength of Pacific Chub Mackerel

by Kohei Hasegawa, Naizheng Yan, Tohru Mukai, Yoshiaki Fukuda and Jun Yamamoto

Fishes 2025, 10(2), 51; https://doi.org/10.3390/fishes10020051 - 28 Jan 2025

Cited by 3 | Viewed by 2226

Abstract

Broadband backscattering measurements of Pacific mackerel (Scomber japonicus) can improve acoustic surveys of the species for the management of its fisheries throughout the Pacific Ocean. The determination of its target strength (TS), the logarithmic form of the backscattering cross-section, is the [...] Read more.

Broadband backscattering measurements of Pacific mackerel (Scomber japonicus) can improve acoustic surveys of the species for the management of its fisheries throughout the Pacific Ocean. The determination of its target strength (TS), the logarithmic form of the backscattering cross-section, is the aim of this work. It was measured for fourteen individual specimens, eight in a freshwater tank and six in a seawater tank, using calibrated broadband echosounders spanning the frequency band 24–84 kHz. The TS is expressed as a function of frequency and tilt angle, with fish length as a parameter. The individual broadband TS patterns with the tilt angle of fish showed size and frequency dependencies. The fish length-normalized TS of mackerel decreased with increasing fish length-to-acoustic wavelength ratio (l/λ) in the small l/λ range (approximately 2–6) but was flat in the larger l/λ range (>6). This variation in the normalized TS indicates that a pair of regression equations is necessary to span the range of commercially important mackerel relative to the acoustic wavelength. The relative l/λ characteristic of the normalized TS showed constant values with tilt-angle distributions over a large l/λ range and can be used as a characteristic of acoustic backscattering for discrimination among species. Full article

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

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14 pages, 2848 KB

Open AccessEditor’s ChoiceArticle

Establishing the Physiological Values of Minimally Invasive Biomarkers in Gilthead Sea Bream (Sparus aurata)

by Rafael Angelakopoulos, Andreas Tsipourlianos, Alexia E. Fytsili and Katerina A. Moutou

Fishes 2025, 10(2), 52; https://doi.org/10.3390/fishes10020052 - 28 Jan 2025

Cited by 1 | Viewed by 2191

Abstract

Peripheral blood has been always used as the mirror of physiological status in a minimally invasive manner. In homeothermic vertebrates, different blood parameters have been correlated to a variety of biochemical and physiological processes and the establishment of physiological values have rendered them [...] Read more.

Peripheral blood has been always used as the mirror of physiological status in a minimally invasive manner. In homeothermic vertebrates, different blood parameters have been correlated to a variety of biochemical and physiological processes and the establishment of physiological values have rendered them valuable indicators for research, diagnosis, and welfare status. Despite the volume of research in fish physiology and teleost significance for food security, information about the physiological values of minimally invasive biomarkers is still fragmented while there is a great need for such biomarkers for monitoring fish health, welfare, and factors that can impact their homeostasis. For the first time, we have focused on determining the physiological ranges of cholesterol, triglycerides, and total proteins in the plasma of gilthead sea bream (Sparus aurata) and detecting how size, diet, environment, and genetic background may influence these levels. A large heterogeneous dataset of 5318 healthy individuals of two different size classes (1–100 g; 101–200 g), dietary status (10 feeds and feeding regimes), and different genetic background (125 families), in combination with different geographic locations (GxE), was produced over a period of three years and analyzed to ensure a comprehensive representation in establishing the physiological range for these biomarkers. Dietary status and GxE introduced significant variations in the range of the physiological values of all biomarkers in both size classes. Triglyceride, total protein and cholesterol values did differentiate with age/size. Interestingly, all parameters responded to diet in a size-specific way, revealing their potential as biomarkers of dietary status. Full article

(This article belongs to the Special Issue Environmental Physiology of Aquatic Animals)

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17 pages, 6115 KB

Open AccessEditor’s ChoiceArticle

Black Sea Bass Centropristis striata Year Class Strength and Spatial Extent from Two Long-Term Surveys off the Southeast U.S. Atlantic Coast

by Julie L. Vecchio, Margaret W. Finch, Kevin R. Spanik, Amy Zimney and Tracey I. Smart

Fishes 2025, 10(2), 53; https://doi.org/10.3390/fishes10020053 - 28 Jan 2025

Cited by 1 | Viewed by 2849

Abstract

The Southeastern U.S. Atlantic coast (North Carolina to Florida, U.S.A.) has undergone considerable environmental change in recent decades, including increasing coastal water temperature and human development. The region is also home to a diverse suite of exploited reef fish species, including the southern [...] Read more.

The Southeastern U.S. Atlantic coast (North Carolina to Florida, U.S.A.) has undergone considerable environmental change in recent decades, including increasing coastal water temperature and human development. The region is also home to a diverse suite of exploited reef fish species, including the southern stock of black sea bass (Centropristis striata). The objective of the current study was to compare trends in black sea bass year class strength and central location captured by trawls (age 0) and traps (age 2) as well as compare those trends to regional bottom temperature. We found no correlation between age 0 and age 2 abundance when comparing the same year class, suggesting that the numbers of trawl-caught juveniles cannot predict the number of adults available to the fishery. Larger year classes observed in traps were correlated with centers of abundance farther south in the region, while smaller year classes corresponded with more northerly centers of abundance. In both trawls and traps, strong year classes occurred following years with below-average regional water temperatures, and a series of recent, weak year classes correspond with recent higher-than-average water temperatures. It is unclear whether correlations between shifting centers of abundance, year class strength, and regional bottom temperature indicate a range contraction for the southern stock of black sea bass or movement into areas previously inhabited by the northern stock of the species. Full article

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

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21 pages, 789 KB

Open AccessEditor’s ChoiceReview

Pivotal Roles of Fish Nutrition and Feeding: Recent Advances and Future Outlook for Brazilian Fish Farming

by Aline Brum, Caio Magnotti, Mônica Yumi Tsuzuki, Elen Monique de Oliveira Sousa, José Luiz Pedreira Mouriño, Maurício Laterça Martins, Rafael Garcia Lopes, Roberto Bianchini Derner and Marco Shizuo Owatari

Fishes 2025, 10(2), 47; https://doi.org/10.3390/fishes10020047 - 27 Jan 2025

Cited by 20 | Viewed by 10295

Abstract

The aquafeed industry evolved alongside fish farming, utilizing scientific and technological advancements to incorporate a variety of feed additives, supplements, and alternative ingredients in the nutrition and feeding of fish in aquaculture. These advances played a significant role in improving the production, health, [...] Read more.

The aquafeed industry evolved alongside fish farming, utilizing scientific and technological advancements to incorporate a variety of feed additives, supplements, and alternative ingredients in the nutrition and feeding of fish in aquaculture. These advances played a significant role in improving the production, health, and welfare of farmed fish. Recent research in Brazil highlighted the importance of using fish feed additives, such as vitamins, minerals, and amino acids, to ensure that farmed fish receive all the necessary nutrients for growth and health. Functional additives can enhance the immune system, boosting disease resistance and promoting the overall health of fish. Antimicrobial and antiparasitic additives help prevent and treat infections and infestations, reducing the occurrence of disease outbreaks. Additionally, some additives improve feed digestibility, leading to better nutrient absorption and reduced feed requirements. Overall, nutritional strategies are essential for optimizing fish farming practices in Brazil and globally, promoting fish health and sustainability in the industry. This review emphasizes the significance of certain additives, supplements, and ingredients strategically incorporated into experimental feeds for research in Brazilian fish farming. It also underscores the necessity for ongoing research. There is a noticeable trend towards developing more sustainable and efficient feeds, which is essential for the future of sustainable aquaculture. The goal is to minimize environmental impacts while maintaining economic viability in aquaculture operations. Full article

(This article belongs to the Special Issue Pivotal Roles of Feed Additives for Fish)

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16 pages, 2995 KB

Open AccessEditor’s ChoiceArticle

Taurochenodeoxycholic Acid Improves Growth, Physiology, Intestinal Microbiota, and Muscle Development in Red Swamp Crayfish (Procambarus clarkii)

by Xiaodi Xu, Xiaochuan Zheng, Changyou Song, Xin Liu, Qunlan Zhou, Cunxin Sun, Aimin Wang, Aiming Zhu and Bo Liu

Fishes 2025, 10(2), 38; https://doi.org/10.3390/fishes10020038 - 22 Jan 2025

Cited by 2 | Viewed by 2285

Abstract

Taurochenodeoxycholic acid (TCDCA), one of the bile acids, is thought to be involved in the regulation of muscle nutrient metabolism and gut microbial homeostasis. However, the effect of dietary addition of TCDCA on Procambarus clarkii is unclear. Therefore, in this study, an 8-week [...] Read more.

Taurochenodeoxycholic acid (TCDCA), one of the bile acids, is thought to be involved in the regulation of muscle nutrient metabolism and gut microbial homeostasis. However, the effect of dietary addition of TCDCA on Procambarus clarkii is unclear. Therefore, in this study, an 8-week feeding experiment was conducted to explore the potential regulatory mechanisms of TCDCA on P. clarkii growth, physiology, muscle quality and gut microbes. The results indicated that dietary addition of TCDCA not only improved growth performance (final weight; weight gain; and specific growth rate) but also increased muscle elasticity and protein content. In addition, dietary TCDCA promotes muscle growth and development by increasing myofiber length, which is consistent with the activation of the expression of genes related to protein utilization (TOR and AKT) and muscle proliferation and differentiation (MyHC, MLC1, MEF2A, MEF2B). Importantly, 16s rRNA sequencing demonstrated that dietary TCDCA had no significant effect on gut microbial composition (alpha diversity) but significantly increased microbial abundance at the genus level. Functional prediction analysis of differential microbes revealed that dietary TCDCA may promote metabolism by altering gut microbes, thereby promoting muscle quality. In conclusion, our study demonstrates that the dietary addition of TCDCA promotes P. clarkii growth and muscle quality and protein deposition by altering gut microbes. Full article

(This article belongs to the Special Issue Effect of Dietary Supplementation on the Growth and Immunity of Fish and Shellfish—2nd Edition)

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14 pages, 9625 KB

Open AccessEditor’s ChoiceArticle

Mutation of Genes Associated with Body Color, Growth, Intermuscular Bone, and Sex Differentiation in Onychostoma macrolepis Using CRISPR/Cas9

by Tian Gao, Feilong Wang, Qihui Wu, Lingyao Gan, Canbiao Jin, Li Ma, Deshou Wang and Lina Sun

Fishes 2025, 10(2), 40; https://doi.org/10.3390/fishes10020040 - 22 Jan 2025

Cited by 4 | Viewed by 3531

Abstract

Onychostoma macrolepis is not only a protected Cyprinid species in the wild but also an emerging commercial aquaculture fish in China. The objective of this research was to genetically modify the genes associated with commercial traits by CRISPR/Cas9 for the protection and utilization [...] Read more.

Onychostoma macrolepis is not only a protected Cyprinid species in the wild but also an emerging commercial aquaculture fish in China. The objective of this research was to genetically modify the genes associated with commercial traits by CRISPR/Cas9 for the protection and utilization of the germplasm resources of O. macrolepis. To that end, one-cell stage embryos were obtained via hormone-induced ovulation and artificial insemination in O. macrolepis. Eight genes related to body color, growth, intermuscular bone, and sex differentiation were mutated in O. macrolepis using the CRISPR/Cas9 system by microinjection of gRNA/Cas9 mRNA. The optimal dose of gRNA/Cas9 mRNA was determined by injection of different concentrations of tyr (tyrosinase)-gRNA/Cas9 and examination of the mutation rate and hatching rate of embryos. Indels were detected by T7 endonuclease I digestion and Sanger sequencing. F0 mutants with high mutation rates were selected for phenotype analyses. Disruption of body color gene tyr, mpv17 (mitochondrial inner membrane protein MPV17), and csf1ra (colony-stimulating factor 1 receptor, a) resulted in obvious phenotype with decreased or even absence of melanophores, iridophores, and xanthophores, respectively. Mutation of mstnb (myostatin b) led to improved growth performance. Mutation of mc4r (melanocortin 4 receptor) led to no obvious phenotype. Mutation of runx2b (RUNX family transcription factor 2b) and bmp6 (bone morphogenetic protein 6) resulted in decreased or absence of intermuscular bones, as revealed by alizarin red S staining. Mutation of cyp19a1a (cytochrome P450, family 19, subfamily A, polypeptide 1a) resulted in ovarian degeneration as revealed by gonadal histological examination. Therefore, this study successfully obtained mutants with obvious phenotypes of genes associated with body color, growth, intermuscular bone, and sex differentiation by CRISPR/Cas9 in O. macrolepis. Full article

(This article belongs to the Special Issue Advances in Germplasm Resources and Genetic Breeding of Aquatic Animals)

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19 pages, 5919 KB

Open AccessEditor’s ChoiceArticle

The Tasmanian Estuary Perch Population—A Threatened Species?

by Jonah L. Yick, Bryan Van Wyk and James Haddy

Fishes 2025, 10(1), 31; https://doi.org/10.3390/fishes10010031 - 15 Jan 2025

Cited by 1 | Viewed by 2907

Abstract

Estuary perch (Percalates colonorum) are a long-lived and slow-growing species which are distributed throughout southeastern Australian estuaries. In Tasmania, only one known population remains which is located in the Arthur River, on the remote northwest coast. Tasmania is the only Australian [...] Read more.

Estuary perch (Percalates colonorum) are a long-lived and slow-growing species which are distributed throughout southeastern Australian estuaries. In Tasmania, only one known population remains which is located in the Arthur River, on the remote northwest coast. Tasmania is the only Australian state to list estuary perch as a wholly protected species (recreational and commercial), while other populations across their mainland distribution appear to be robust. A survey undertaken on estuary perch in the Arthur River in 2014–2015 indicated that the population was small (825–2375 fish) and dominated by three age classes between 12 and 14 years old. This population also has extremely low genetic diversity and is genetically distinct to mainland populations due to its geographic isolation. During a re-survey in December 2023, 378 estuary perch were captured, with 191 tagged and released, and 31 fish retained for age and gonad analysis. Although three strong age classes were detected (five, eight and twenty-three years), numerous weak and missing cohorts were apparent. This study also confirms this population has a delayed spawning season in comparison to mainland populations, with growth models and tag recaptures (32 fish) demonstrating a very slow but sexually dimorphic growth rate. By combining the datasets of the 2014/15 and 2023 survey, we present an updated understanding of the biology and population dynamics of this unique Tasmanian population, which has previously never been published. The results confirm the population is still reproductively active and stable; however, due to their restricted distribution, variable recruitment, slow growth, and small population, further conservation efforts are still required. Further legislative listings at both the state and federal levels are possible, which if progressed could provide additional protection and assist in applications for external funding and resources. This will support the development of a recovery plan which will consider re-stocking efforts and re-establishment of previously inhabited waters and investigate potential actions to improve the genetics of the Tasmanian population. Additionally, educational campaigns to inform the public and recreational fishers on the status of estuary perch in Tasmania will be undertaken. 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, 15465 KB

Open AccessEditor’s ChoiceArticle

Functional Involvement of Melatonin and Its Receptors in Reproductive Regulation of the Marine Teleost, Large Yellow Croaker (Larimichthys crocea)

by Xudong Liang, Jixiu Wang, Baoyi Huang, Haojie Yuan, Yucheng Ren, Chenqian Wu, Tianming Wang and Jingwen Yang

Fishes 2025, 10(1), 28; https://doi.org/10.3390/fishes10010028 - 10 Jan 2025

Cited by 8 | Viewed by 3906

Abstract

Melatonin is a critical regulator of biological rhythms across organisms, transducing light signals into neuroendocrine signals that facilitate reproductive regulation in response to environmental cues. However, the precise mechanisms through which melatonin regulates reproduction in fish require further investigation. In this study, we [...] Read more.

Melatonin is a critical regulator of biological rhythms across organisms, transducing light signals into neuroendocrine signals that facilitate reproductive regulation in response to environmental cues. However, the precise mechanisms through which melatonin regulates reproduction in fish require further investigation. In this study, we employed molecular and organizational biological techniques to examine the expression patterns of melatonin and its five receptor subtypes (LcMTNR1A1, LcMTNR1A2, LcMTNR1B1, LcMTNR1B2, and LcMTNR1C) in various tissues of the large yellow croaker (Larimichthys crocea). Our results revealed significant expression of all receptors in the pituitary and testes, with distinct gender differences, including a lack of expression in the ovary. Moreover, our data indicate that melatonin and its receptors are primarily expressed during stage III, highlighting their role in sexual maturity. Enzyme- linked immunosorbent assay (ELISA) results further demonstrated that in vitro melatonin incubation in the brain of L. crocea influenced gonadotropin-releasing hormone (GnRH) and testosterone secretion in a dose-dependent manner, suggesting actions beyond the classical hypothalamic–pituitary–gonadal (HPG) axis. Overall, our findings provide new evidence supporting the role of the melatonin system in reproductive regulation in marine teleosts. Full article

(This article belongs to the Special Issue Rhythms in Marine Fish and Invertebrates)

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16 pages, 1446 KB

Open AccessEditor’s ChoiceArticle

A Study on the Dietary Yeast Polysaccharide Supplementation in Growth Performance, Antioxidant Capacity, and Immunity of Juvenile Largemouth Bass (Micropterus salmoides)

by Junjie Qin, Haifeng Mi, Mingchun Ren, Dongyu Huang, Hualiang Liang, Lu Zhang, Tao Teng and Heng Yin

Fishes 2025, 10(1), 26; https://doi.org/10.3390/fishes10010026 - 8 Jan 2025

Cited by 3 | Viewed by 3056

Abstract

The aim of this study was to investigate the effects of dietary yeast polysaccharide (YPS) supplementation on the growth performance, whole-body composition, antioxidant capacity, and immunity of juvenile largemouth bass (Micropterus salmoides). In this study, five diets with YPS levels of [...] Read more.

The aim of this study was to investigate the effects of dietary yeast polysaccharide (YPS) supplementation on the growth performance, whole-body composition, antioxidant capacity, and immunity of juvenile largemouth bass (Micropterus salmoides). In this study, five diets with YPS levels of 0.00% (control), 0.05% (0.05Y), 0.10% (0.10Y), 0.15% (0.15Y), and 0.20% (0.20Y) were designed and prepared. A total of 300 healthy fish (3.20 ± 0.03 g) were randomly divided into 15 floating cages (1 × 1 × 1 m) in five different groups, with three replicates per group, for an 8-week culture experiment. The 0.10Y and 0.20Y groups had significantly higher feed conversion ratios compared with the control group. There was no significant effect on any of the other growth indicators. Plasma biochemical indices showed that the 0.10Y group exhibited the highest plasma alkaline phosphatase content and the 0.20Y group exhibited the highest plasma glucose content. Plasma antioxidant indices (total antioxidant capacity, superoxide dismutase, and glutathione) and antioxidant genes (catalase and superoxide dismutase) were elevated in the 0.05Y or 0.10Y groups, and the malondialdehyde content decreased with increasing YPS concentration. Moreover, the 0.05Y group showed significantly higher immune-related gene (nuclear factor-kappa B, interleukin-8, and interleukin-10) mRNA expression. Altogether, our results indicate that dietary YPS supplementation enhances the antioxidant and immune capacity of M. salmoides, but with no positive effect on their growth. Full article

(This article belongs to the Special Issue Fish Nutrition and Immunology)

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25 pages, 3584 KB

Open AccessEditor’s ChoiceArticle

A Metapopulation Model to Assess Water Management Impacts on the Threatened Australian Lungfish, Neoceratodus forsteri

by Charles R. Todd, Andrew J. McDougall, Scott M. C. Raymond, Robin Hale, Timothy R. Brown, John D. Koehn, Henry F. Wootton, Steven G. Brooks, Adrian M. Kitchingman, Tom Espinoza, Benjamin G. Fanson, Peter K. Kind, Sharon M. Marshall and David T. Roberts

Fishes 2025, 10(1), 22; https://doi.org/10.3390/fishes10010022 - 7 Jan 2025

Viewed by 3074

Abstract

The Australian lungfish, Neoceratodus forsteri, is one of the world’s oldest vertebrate lineages, with a slow life-history and threatened status, requiring immediate conservation efforts. The main threats to lungfish populations are degradation and availability of key macrophyte habitats, water regulation and flow [...] Read more.

The Australian lungfish, Neoceratodus forsteri, is one of the world’s oldest vertebrate lineages, with a slow life-history and threatened status, requiring immediate conservation efforts. The main threats to lungfish populations are degradation and availability of key macrophyte habitats, water regulation and flow modification. As this long-lived species (at least 77 years) has delayed maturity (mature at 10 years), field monitoring alone will not be enough to inform the challenge of ensuring sustainable populations. A stochastic metapopulation model was developed for the Burnett River (Southeast Queensland, Australia), an important habitat for the lungfish that is a highly regulated system with extensive water infrastructure. The model consists of three interacting populations, where the ecology and biology of the species were translated into an 80-year-class population projection matrix for each population, each with post-development streamflow, habitat and movement rules. The model highlights the longer-term interaction between dams and stream flows on habitat availability and subsequent recruitment. Through a pre-development streamflow, we quantify the impact of high regulation and development on the lungfish population in the Burnett River: a minor decline in the upstream population (e.g., 9.8% decline), a large decline in the middle population (64.2% decline), virtually no change in the downstream population (e.g., 1.2% decline) and a moderate decline in the overall metapopulation (e.g., 22.3% decline). The loss of spawning and feeding habitat remains the main reason for population decline, with implications that the loss will lead to greater pressure on remaining downstream habitat due to combined flow and dam effects and, in turn, to extended periods of recovery of spawning habitat. Our modeling approach substantially advances conservation management of this species, as it can be adapted to suit other populations in other river systems and used to test sensitivity to recovery actions. Full article

(This article belongs to the Section Biology and Ecology)

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22 pages, 2144 KB

Open AccessEditor’s ChoiceArticle

Heart Rate Monitoring During Behavioral Stress Tests in Bold and Shy Rainbow Trout (Oncorhynchus mykiss)

by Eleftherios Kasiouras, Gautier Riberolles, Albin Gräns, Andreas Ekström, Johan Höjesjö, Jonathan A. C. Roques, Erik Sandblom and Lynne U. Sneddon

Fishes 2025, 10(1), 23; https://doi.org/10.3390/fishes10010023 - 7 Jan 2025

Cited by 2 | Viewed by 3891

Abstract

Monitoring stress in captive fish is crucial for their welfare, but continuous physiological measures in unrestrained animals are challenging. Rainbow trout (Oncorhynchus mykiss) exhibit divergent personalities, ranging from bold to shy, which correlate with cortisol-mediated stress responses. To determine whether personality [...] Read more.

Monitoring stress in captive fish is crucial for their welfare, but continuous physiological measures in unrestrained animals are challenging. Rainbow trout (Oncorhynchus mykiss) exhibit divergent personalities, ranging from bold to shy, which correlate with cortisol-mediated stress responses. To determine whether personality affects the sympathetic nervous system, heart rate was measured during three potentially stressful events as a proxy for sympathetic nervous system responses. Firstly, trout were classified as bold or shy, using a novel object test. Subsequently, trout were implanted with biologgers to record heart rate in vivo at rest during and after the behavioral tests. Following recovery, the fish underwent a second novel object test, a confinement test, a pair-wise contest, and a final novel object test to explore the degree of boldness over the experimental period, which remained consistent. Heart rate was relatively higher in both bold and shy animals during the confinement test and the pair-wise contest compared with the novel object test, which indicated that heart rate monitoring was a valid gauge of the valence of the experience. Heart rate responses did not differ between bold and shy trout, indicating that behavioral phenotype did not influence the autonomic stress response. Thus, heart rate is a reliable indicator of stress without the need to account for intra-specific behavioral variations. Full article

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15 pages, 1806 KB

Open AccessEditor’s ChoiceArticle

Spawning Potential Ratio Can Provide Reference Points for Fishery Management That Are Robust to Environmental Variability

by Kyle W. Shertzer, Matthew D. Damiano and Erik H. Williams

Fishes 2024, 9(12), 497; https://doi.org/10.3390/fishes9120497 - 3 Dec 2024

Cited by 10 | Viewed by 3698

Abstract

Biological reference points are key quantities provided by stock assessments and used in fishery management for evaluating fishery status and setting future catch levels. For many fisheries worldwide, biological reference points are based on the spawning potential ratio (SPR), which measures per-recruit reproductive [...] Read more.

Biological reference points are key quantities provided by stock assessments and used in fishery management for evaluating fishery status and setting future catch levels. For many fisheries worldwide, biological reference points are based on the spawning potential ratio (SPR), which measures per-recruit reproductive output as a function of the fishing rate relative to that when fishing is absent. SPR depends on the biological characteristics of the stock, which in turn can be influenced by the environment. A fishing rate based on SPR is often used as a proxy for the fishing rate that provides maximum sustainable yield. Here, we evaluate variability in the fishing rate (F₄₀) that provides an SPR of 40%, a commonly used limit reference point, given plausible variability in biological characteristics. Using eight case-study species from marine waters off the southeast United States, we consider both simple random variability and directional variability, both of which might result from climate change. We test the sensitivity of F₄₀ to various life-history traits and compute distributions of F₄₀, given the expected variability in those traits. Based on those distributions, we evaluate the probabilities of overfishing given a target fishing rate (here, 75%F₄₀) that is based on prevailing conditions without considering future variability in F₄₀, consistent with common, current practice. Analyses also considered an SPR of 30% and 50% to evaluate the generality of conclusions. Results support that SPR-reference points are generally robust to plausible levels of variability in life-history traits that might be induced by environmental nonstationarity and that associated target fishing rates can provide meaningful buffers to prevent overfishing. Full article

(This article belongs to the Special Issue Fisheries Stock Assessment and Modeling)

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17 pages, 1652 KB

Open AccessEditor’s ChoiceArticle

Hepatic Gene Expression Changes of Zebrafish Fed Yeast Prebiotic, Yeast Probiotic, Black Soldier Fly Meal, and Butyrate

by Nancy Gao, Junyu Zhang, Umesh K. Shandilya, John S. Lumsden, Amir Behzad Barzrgar, David Huyben and Niel A. Karrow

Fishes 2024, 9(12), 495; https://doi.org/10.3390/fishes9120495 - 2 Dec 2024

Cited by 3 | Viewed by 3149

Abstract

As global fish consumption rises, improving fish health through immunomodulatory feed ingredients shows promise while also supporting growth performance. This study investigated the effects of yeast prebiotics, probiotics, a postbiotic (butyrate), and black soldier fly larvae (BSFL) meal on fish immune responses. Zebrafish [...] Read more.

As global fish consumption rises, improving fish health through immunomodulatory feed ingredients shows promise while also supporting growth performance. This study investigated the effects of yeast prebiotics, probiotics, a postbiotic (butyrate), and black soldier fly larvae (BSFL) meal on fish immune responses. Zebrafish were fed diets containing these ingredients for 63 days and then exposed to either Pseudomonas aeruginosa lipopolysaccharide (LPS) or live Flavobacterium psychrophilum to assess hepatic candidate gene expression and weight gain. No mortalities were observed post-immune challenges, and weight gains were not significantly different across treatments. Liver samples were collected for mRNA analysis, and real-time qPCR was used to evaluate the expression of immune-related genes such as TNF-α, IL-1β, hepcidin, and NF-κB/p65. NF-κB/p65 was upregulated in response to immune challenges, indicating a reaction to both LPS and pathogen exposure. Fish on the BSFL diet showed decreased NF-κB/p65 expression after the pathogen challenge, while probiotic-fed fish had reduced angiopoietin-like 4 (angptl4) levels following LPS exposure. Butyrate supplementation had the most significant impact, downregulating pro-inflammatory cytokines and other immune-related genes, suggesting a protective effect. These findings support the health benefits of BSFL and sodium butyrate during an immune challenge. Full article

(This article belongs to the Special Issue Effect of Dietary Supplementation on the Growth and Immunity of Fish and Shellfish—2nd Edition)

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17 pages, 8321 KB

Open AccessEditor’s ChoiceArticle

Ease and Limitations in Using Environmental DNA to Track the Spread of Invasive Host–Parasite Complexes: A Case Study of the Freshwater Fish Pseudorasbora parva and the Cryptic Fungal Parasite Sphaerothecum destruens

by Théo Deremarque, Rodolphe Elie Gozlan, Ravo Ravaozafindrasoa, Giuliano Mucci, Lucie Delalex, Jean-Michel Foissy, Michaël Cagnant, Mathieu Clair, Justina Givens, Fabienne Justy, Alice Valentini, Delphine Nicolas, Pascal Contournet, Claire Tetrel, Marc Thibault and Marine Combe

Fishes 2024, 9(12), 477; https://doi.org/10.3390/fishes9120477 - 26 Nov 2024

Viewed by 2676

Abstract

The spread of non-native species threatens biodiversity and exacerbates societal challenges like food security. To address this, effective conservation programs require detection methods that are easy to implement, accurate, and non-invasive. Over the past 15 years, environmental DNA (eDNA) techniques have gained popularity, [...] Read more.

The spread of non-native species threatens biodiversity and exacerbates societal challenges like food security. To address this, effective conservation programs require detection methods that are easy to implement, accurate, and non-invasive. Over the past 15 years, environmental DNA (eDNA) techniques have gained popularity, surpassing traditional sampling methods. In this context, our study focused on tracking the invasive host–pathogen complex Pseudorasbora parva and Sphaerothecum destruens using eDNA metabarcoding. We collected water samples from freshwater canals over five months in the Camargue region, and once in Corsica Island, both in southern France. Total DNA was extracted from filtered water samples, and PCR-amplicons were sequenced using Illumina or Nanopore technologies. Our results revealed a high detection rate of P. parva in lentic ecosystems, aligning with habitat preferences of this small freshwater fish. Additionally, the detection rate in Camargue increased in May and June, likely due to the peak of the spawning season, which leads to more DNA being released into the environment (i.e., concentration and interaction of individuals). While eDNA successfully detected this invasive fish, we were unable to detect its cryptic fungal parasite, S. destruens, highlighting the challenges of identifying intracellular and cryptic fungal pathogens through eDNA methods. Full article

(This article belongs to the Special Issue Detection and Monitoring of Aquatic Pathogens by Using Environmental DNA (eDNA))

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14 pages, 1377 KB

Open AccessEditor’s ChoiceArticle

The Effects of Predominantly Chemoautotrophic Versus Heterotrophic Biofloc Systems on Nitrifying Bacteria, Planktonic Microorganisms, and Growth of Penaeus vannamei, and Oreochromis niloticus in an Integrated Multitrophic Culture

by Raysa Pâmela Oliveira Sena, Dariano Krummenauer, Wilson Wasielesky, Jr., Otávio Augusto Lacerda Ferreira Pimentel, Aline Bezerra, Jorge Renato Tagliaferro dos Santos Junior, Andrezza Carvalho, Elisa Ravagnan, Andrea Bagi and Luis H. S. Poersch

Fishes 2024, 9(12), 478; https://doi.org/10.3390/fishes9120478 - 26 Nov 2024

Cited by 4 | Viewed by 3057

Abstract

The aim of this study was to evaluate the effect of predominantly chemoautotrophic and heterotrophic biofloc systems on ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and planktonic microorganisms in an integrated Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. Shrimp and tilapia were stocked [...] Read more.

The aim of this study was to evaluate the effect of predominantly chemoautotrophic and heterotrophic biofloc systems on ammonia-oxidizing bacteria (AOB), nitrite-oxidizing bacteria (NOB), and planktonic microorganisms in an integrated Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. Shrimp and tilapia were stocked at a density of 400 shrimp m⁻² and 45 fish m⁻³, respectively. The trial consisted of two biofloc treatments, with three replicates each: chemoautotrophic and heterotrophic. The identification and quantification of the planktonic microorganisms (ciliates, flagellates, microalgae, and total bacteria) and nitrifying bacteria were carried out through direct counting and fluorescence in situ hybridization, respectively. At the end of the trial, heterotrophic treatment had resulted in higher total abundance of bacteria. The relative abundance of AOB and NOB in relation to the total abundance was less than 0.1% for both treatments. The system was dominated by flagellates in both treatment groups. The abundance of microalgae and ciliates was higher with chemoautotrophic treatment. After 43 days, the shrimp weights were higher in the chemoautotrophic group, while the final weights of the tilapia were not significantly different between the two treatments. The type of biofloc system (Chemoautotrophic vs. Heterotrophic) did not significantly alter the establishment of AOB and NOB in a Penaeus vannamei and Oreochromis niloticus integrated multitrophic culture. The two treatments proved to be equally efficient for maintaining good water quality, but the chemoautotrophic treatment resulted in better shrimp growth. Thus, our study demonstrated that chemoautotrophic biofloc is a promising approach in integrated multitrophic aquaculture. Full article

(This article belongs to the Special Issue Biofloc Technology in Aquaculture)

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