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The Heilongjiang River is one of the largest rivers in the cool temperate zone and has an abundant fish source. To date, the microbiota community in water samples and fish guts from the Heilongjiang River is still unclear. In the present study, water samples and fish guts were collected from four locations of the Heilongjiang River during both the dry season and the wet season to analyze the spatio-temporal dynamics of microbiota communities in the water environment and fish guts through 16s ribosome RNA sequencing. The water qualities showed seasonal changes in which the pH value, dissolved oxygen, and total dissolved solids were generally higher during the dry season, and the water temperature was higher during the wet season. RDA indicated that higher pH values, dissolved oxygen, and total dissolved solids promoted the formation of microbiota communities in the water samples of the dry season, while higher water temperature positively regulated the formation of microbiota communities in the water samples of the wet season. LEFSe identified five biomarkers with the most abundant difference at the genus level, of which TM7a was upregulated in the water samples of the dry season, and SM1A02, Rheinheimera, Gemmatimonas, and Vogesella were upregulated in the water samples of the wet season. Pearson analysis revealed that higher pH values and dissolved oxygen positively regulated the formation of TM7a and negatively regulated the formation of SM1A02, Rheinheimera, Gemmatimonas, and Vogesella (p < 0.05), while higher water temperature had the opposite regulatory roles in the formation of these biomarkers. The relative abundance of microbiota diversity in fish guts varies greatly between different fish species, even if the fishes were collected from the same water source, indicating that dietary habits and fish species may be key factors, affecting the formation and construction of microbiome community in fish gut. P. glenii, P. lagowskii, G. cynocephalus, and L. waleckii were the main fish resources, which were collected and identified from at least six sample points. RDA indicated that the microbiota in the water environment regulated the formation of microbiota community in the guts of G. cynocephalus and L. waleckii and had limited regulated effects on P. glenii and P. lagowskii. The present study identified the regulatory effects of water qualities on the formation of microbiota communities in the water samples and fish guts, providing valuable evidence for the protection of fish resources in the Heilongjiang River. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are crucial for global biodiversity through supporting plant and animal species and providing essential resources. These ecosystems are under significant threat, particularly in island environments such as Madagascar. Our study focuses on the Amboaboa River basin, home to the rare and endemic fish species Rheocles derhami, last recorded in 2013. To assess the status of this and other threatened fish species including Ptychochromis insolitus and Paretroplus gymnopreopercularis, and to understand freshwater fish population dynamics in this biodiversity hotspot, we conducted a comprehensive survey using both environmental DNA (eDNA) and traditional fishing methods. While traditional methods effectively captured a diverse range of species, including several invasive aliens and the critically endangered endemic species that were the focus of this study, the eDNA approach detected only a fraction of these introduced species and struggled to identify some critically endangered endemics at the species level. This highlights the value of combining methods to enhance species detection. We also investigated the trade-offs associated with multi-primer assessments in eDNA analysis, focusing on three different primer combinations targeting the 12S mitochondrial gene: MiFish, Tele02, and Riaz. Additionally, we provided 12S reference barcodes for 10 species across 9 genera of fishes from the region to increase the coverage of the public reference databases. Overall, our study elucidates the current state of freshwater biodiversity in the Amboaboa River basin and underscores the value of employing multiple methods for effective conservation strategies. [ABSTRACT FROM AUTHOR]

Freshwater streams are frequently fragmented by infrastructure that has the potential to alter stream fish assemblage structure. However, separating natural vs anthropogenically derived assemblage structuring mechanisms within fragmented riverscapes can be challenging. Riverscape concepts such as the river continuum concept (RCC), serial discontinuity concept (SDC), and network dynamics hypothesis (NDH) conceptualize the roles of natural and anthropogenic regulators of assemblage structure along longitudinal gradients in streams. Each of these theories approaches the influence of stream continuity and discontinuity differently, and their application to metacommunity ecology might identify natural vs anthropogenic drivers of assemblage structure. Over 3 y, we surveyed fish assemblages and habitat variables from 40 sites along the longitudinal dimension of White Creek, a headwater stream in College Station, Texas, USA, to test theory-based hypotheses regarding the structuring of fish metacommunities. To achieve this goal, we constructed asymmetric eigenvector maps (AEMs) that integrated aspects of the RCC, NDH, and SDC theories and used these AEMs to test 3 hypotheses: (H1) fish species richness increases longitudinally downstream, but fragmentation by road–stream crossings causes repeated disruptions to this increase, as predicted by the SDC; (H2) spatial contexts based on the SDC explain more variation in metacommunity structure compared with RCC, NDH, or a neutral model; and (H3) distinct fish assemblages exist within fragments of stream created by impassable road–stream crossings. Competing generalized additive models based on stream theories indicated the SDC was the top-ranked model for predicting longitudinal increase in species richness, supporting H1. Spatial variables from the theory-integrated AEMs explained more variation in assemblage structure relative to the neutral model (particularly for the SDC model), supporting H2. Assemblage clustering and ordination showed unique assemblage structure in 3 of the 4 fragments, providing partial support for H3. Our results advance the goal of bridging the gap between theory and conservation of stream fishes by indicating that integration of stream ecosystem theories provides insight to the origins of spatial processes that regulate assemblage structure. Moreover, our results highlight that management of fragmented stream ecosystems might benefit from perspectives that frame anthropogenic alterations within the context of the natural architecture of riverscapes. [ABSTRACT FROM AUTHOR]

BACKGROUND: The recurrent contaminations of feed materials with mycotoxigenic fungi can endanger both farmed animals and humans. Biosynthesized nanomaterials are assumingly the ideal agents to overcome fungal invasion in feed/foodstuffs, especially when utilizing sustainable sources for synthesis. Herein, the phycosynthesis of selenium nanoparticles (SeNPs) was targeted using Cystoseira myrica algal extract (CE), and the conjugation of CE/SeNPs with chitosan nanoparticles (NCt) to produce potential antifungal nanocomposites for controlling Aspergillus flavus isolates in fish feed. RESULTS: The phycosynthesis of SeNPs with CE was effectually carried out and validated using visible/UV analysis, X‐ray diffraction and transmission microscopy; CE/SeNPs had diameters of 8.7 nm and spherical shapes. NCt/CE/SeNPs nanocomposite (173.3 nm mean diameter) was achieved and the component interactions were validated via infrared spectroscopic analysis. The antifungal assessment of screened nanomaterials against three Aspergillus flavus strains indicated that NCt/CE/SeNPs exceeded the fluconazole action using qualitative/quantitative assays. Severe alteration/distortions in A. flavus mycelial structure and morphology were microscopically observed within 48 h of NCt/CE/SeNPs treatment. The treatment of feed ingredients (crushed corn and feed powder) by blending with nanomaterials (NCt, CE/SeNPs and NCt/CE/SeNPs) led to significant reduction in A. flavus count/growth after storage for 7 days; NCt/CE/SeNPs could completely inhibit any fungal growth in feed material. CONCLUSION: The pioneering phycosynthesis of CE/SeNPs and their nanoconjugation with NCt generated bioactive antifungal agents to control A. flavus strains. The innovatively constructed NCt/CE/SeNPs nanocomposite is advised for application as an effectual, biosafe and natural fungicidal conjugate for the protection of fish feed from mycotoxigenic fungi. © 2024 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Globally, freshwater fishes are among the taxa most vulnerable to climate change but are generally understudied in tropical island ecosystems where climate change is predicted to alter the intensity, frequency and duration of extreme flow events. These changes may impact stream ecosystems and native and non‐native biota in complex ways.We compiled an extensive dataset of fish assemblages collected at 119 sites across the Caribbean island of Puerto Rico from 2005 to 2015. We coupled these data with stream flow indices and dam height to understand associations between flow and fish assemblage structure. Sixteen percent of sites contained exclusively non‐native species, 34% contained exclusively native species, and 50% contained native and non‐native species.We built generalised linear models and conducted all subsets model selection to identify extreme flow variables explaining variation in native and non‐native species richness and biomass. We also built models to determine the combined effects of extreme flows and the presence of non‐native species on native species richness and biomass.Extreme flows and dam height were important in explaining variations in native and non‐native species richness and biomass. Model averages showed native biomass decreased by 0.42 kg/ha with a 1‐m increase in dam height, by 0.05 kg/ha with 1 cm/s increase in maximum mean daily high flow and by 3.45 kg/ha with each additional day increase in maximum high flow duration, and increased by 2.06 kg/ha with each additional day increase in mean high flow duration. Model averages predicted that non‐native biomass increased by 1.32 kg/ha with a 1‐m increase in dam height and by 0.01 kg/ha with each additional day increase in mean high flow duration, and decreased by 0.36 kg/ha with each additional day increase in maximum high flow duration. Model averages also predicted an increase in native and non‐native biomass of 0.71 gage and 0.06 kg/ha, respectively, with each additional day increase in maximum low flow duration.The combined effects of non‐native species presence and extreme flows changed the relationship between maximum high and low flow durations and native biomass. Model averages showed that native biomass increased by 1.83 kg/ha with each additional day increase in maximum high flow duration and decreased by 2.52 kg/ha with each additional day increase in maximum low flow duration when non‐native species were present.Native fishes may be able to better cope with longer maximum durations of low flows than expected when non‐native fishes are absent. In mixed fish assemblages, extended maximum durations of high flows may act as a control of non‐native species and dampen their negative effect on native species, but longer maximum durations of low flows may heighten the negative effects of non‐native fishes.Our results are informative for tropical island ecosystems globally and can guide the management and conservation of native fishes, particularly when faced with the dual threats of climate change and non‐native species. Managers may consider increasing efforts to conserve native fishes in Caribbean rivers by maintaining connectivity and habitat complexity while preventing non‐native species introductions. [ABSTRACT FROM AUTHOR]

The present study was conducted to document the fish fauna and their IUCN status of Chessore sub-division of Shamator, Nagaland for a period of one year, from May 2023 - April 2024 covering the targeted areas. The survey reveals the presence of 20 species belonging to 5 orders, 9 families and 15 genera. The order Cypriniformes dominanted with 14 species while Anabantiformes, Perciform and Synbranchiformes with 1 species each is the least common. According to IUCN Red-list and habitat studies during different seasons, one species belonging to family cyprinidae is under IUCN-NT category, five species belonging to cyprinidae, channidae and cobitidae is under IUCN-VU while the rest falls under IUCN-LC and Data deficient (DD) category. A primary threat to the fish biodiversity in study area is due to anthropogenic activities and environmental changes. [ABSTRACT FROM AUTHOR]

Over one third of sharks, rays and chimaeras (chondrichthyans) are threatened with extinction globally. In the Mediterranean Sea, more than half of chondrichthyan species face this risk, although a variety of international, regional, and national rules and regulations apply directly and indirectly targeting management and conservation for these species. In this work, we provide an overview of relevant legislation and policies in the region, which regulate, inter alia, commercial fisheries, while highlighting through cases studies how implementation in practice at national level looks like. Horizontal gaps and inconsistencies that hinder chondrichthyan management in the region are also illustrated. Furthermore, we present recommendations for improvement and additional tools that can be used, even if not originally or explicitly targeting chondrichthyans, for improving the management of these taxa in the Mediterranean. [ABSTRACT FROM AUTHOR]

The demand for creative solutions to help migrate fish and conservation efforts grows as aquatic environments experience more and more pressure from humans and fragmentation of habitat. The utilization of hydroacoustic technology for communication in conjunction with smart fish pathway architecture is the main emphasis of this research to improve rehabilitation efforts for aquatic environments. Using sophisticated systems for tracking and regulation to improve migratory pathways, the study investigates cutting-edge solutions in engineering for fish passage. Real-time data capture and transmission are made possible by the application of hydroacoustic technology for communication, which means that fish populations and monitoring systems can effectively communicate. The creation of intelligent fish passage structures with actuators, sensors, and communications components is a major focus of the research. The best passage efficiency of these structures is ensured by their dynamic adaptation to fish behavior and variables in the environment. An essential interface for gathering information on behavior, evaluating migratory trends, and putting adaptive management plans into practice is hydroacoustic communications technology. In order to assess the efficacy of the hydroacoustic communication technology and smart fish passage design in a variety of aquatic habitats, a thorough field investigation is part of the suggested methodology. To evaluate the effect on migration of fish rates of achievement, species diversity, and general well-being of the ecosystem, field data will be studied. [ABSTRACT FROM AUTHOR]

Wetlands are characterized by flow and environmental dispersion, which are necessary in the water management system. Contaminant transport in wetlands has a significant effect in the field of biology and environmental fluid dynamics for the conservation of fish and wildlife species, erosion prevention, and mainly recreation. When an instantaneous contaminant is released into a wetland, both boundary absorptions and wind have a significant impact on the contaminant dispersion process. The present study highlights the wind effects and boundary absorption on environmental dispersion and stream-wise mean concentration in a width-dominated flow for a shallow wetland. A multi-scale time period is considered to determine the dispersion model, which illustrates the contaminant transport process greatly affected by different ecological parameters like dispersion time, boundary absorption, tortuosity and vegetation drag. It is noted that the stream-wise concentration distribution is almost identical to the transversal concentration distribution due to tortuosity and bottom vegetation effect. It is noticed that the stream-wise concentration of contaminant gradually decreases due to the increase of vegetation parameters and tortuosity. The distribution of flow velocity is derived analytically from the momentum equation for different wind strengths. The effect of boundary absorption strength on stream-wise and mean concentration are discussed. Also, it is evident that the distribution of concentration is complex for boundary absorption under the effects of wind. [ABSTRACT FROM AUTHOR]

Endemic to the upper and middle reaches of the Yangtze River in China, elongate loach (Leptobotia elongata) has become a vulnerable species mainly due to overfishing and habitat destruction. Thus far, no genome data of this species are reported. As a result, lacking of such genomic information has restricted practical conservation and utilization of this economic fish. Here, we constructed chromosome-level genome assemblies for both male and female elongate loach by integration of MGI, PacBio HiFi and Hi-C sequencing technologies. Two primary genome assemblies (586-Mb and 589-Mb) were obtained for female and male fishes, respectively. Indeed, 98.22% and 98.61% of the contig sequences were anchored onto 25 chromosomes, with identification of 26.22% and 25.92% repeat contents in both assembled genomes. Meanwhile, a total of 25,215 and 25,253 protein-coding genes were annotated, of which 97.41% and 98.8% could be predicted with functions. Taken together, our genome data presented here provide a valuable genomic resource for in-depth evolutionary and functional research, as well as molecular breeding and conservation of this economic fish species. [ABSTRACT FROM AUTHOR]

Simple Summary: Fish passage facilities are crucial for restoring river connectivity and protecting ecosystems. This study quantitatively assessed the upstream migration of fish under various environmental conditions. In the Heishuihe River downstream of the Songxin Dam, 19 fish species were monitored, with 15 species reaching the fishway entrance and 12 successfully passing through. The entrance attraction and passage rates of the vertical-slot fishway at Songxin were 15.7% and 40.42%, respectively. The results indicate that May is the optimal period for fish migration, with better performance observed during nighttime than daytime. Optimal entrance attraction occurred at a flow rate of 6–7 m3/s and a temperature of 19–20 °C, while the best passage efficiency was achieved at a flow rate of 0–0.5 m3/s and a temperature of 17–20 °C. A multifactorial Cox regression model identified diurnal rhythms, release location, temperature, and flow rate as primary hindering factors, while body length and water level were found to be promoting factors. A nomogram was developed to predict the success rates of fishway attraction and passage based on these key factors. This study provides theoretical and data support for optimizing fishway operations and offers scientific insights into ecological restoration. Fish passage facilities are essential for restoring river connectivity and protecting ecosystems, effectively balancing economic and ecological benefits. Systematic and comprehensive monitoring, assessment, and optimized management are therefore crucial. This study quantitatively evaluated the entire upstream migration process of fish from the downstream river to the entrance and exit of the fishway and investigated the upstream movement patterns of fish under various environmental factors. A total of 19 fish species were monitored in the Heishuihe River downstream of the dam, with 15 species reaching the fishway entrance and 12 species successfully passing through it. The entrance attraction and passage rates of the vertical-slot fishway at the Songxin hydropower station were 15.7% and 40.42%, respectively. The best upstream performance was observed in May, with fish demonstrating better upstream timing and speed during nighttime compared to daytime. Specifically, the highest entrance attraction efficiency was recorded at a flow rate of 6–7 m3/s and a temperature of 19–20 °C, while the optimal passage efficiency was observed at a flow rate of 0–0.5 m3/s and a temperature of 17–20 °C. Additionally, a multifactorial Cox proportional hazards regression model was constructed to identify key factors influencing the probability of fishway entrance attraction and successful passage. The model elucidated the impact patterns of these key factors on fish upstream migration, ultimately generating an alignment diagram for prediction and control. This study provides a theoretical foundation and data support for developing optimized operational schedules for fishways. The findings offer a more comprehensive and systematic approach for monitoring and evaluating fish passage facilities, serving as a scientific basis for ecological restoration and fish conservation in this region and similar areas. [ABSTRACT FROM AUTHOR]

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Objective: Increasing reliance on numerical simulation models to help inform management and restoration choices benefits from careful consideration of critical early steps in model development. Along the northern coast of the Gulf of Mexico, the eastern oyster Crassostrea virginica fulfills important ecological and economic roles. Using the eastern oyster as an example, we draw on several recent frameworks outlining best practices for model development and application for restoration, conservation, and management. Methods: We identify priority model questions, outline a conceptual ecological model (CEM) to guide numerical model development, and use this framework to identify uncertainties and research needs. Result: The CEM uses a nested design, identifying explicit vital rates, processes, attributes, and outcomes for the species (oysters), population, and metapopulation (i.e., network of populations) levels in response to drivers of species, population, and metapopulation changes and changing environmental factors. Most management actions related to oyster restoration and harvest affect population attributes directly, but many coastal management actions and changes (i.e., climate change and coastal and water resource engineering) impact environmental factors that alter vital rates and attributes of oysters, populations, and metapopulations. Conclusion: Investment in studies targeting individual oyster‐ and population‐level multi‐stressor responses (filtration, respiration, growth, and reproduction) and improving hydrodynamic and environmental models targeting drivers that influence metapopulation vital rates and attributes (i.e., connectivity and substrate persistence) would contribute to reducing uncertainties. Development of numerical models covering the entire oyster life cycle and connectivity of populations using hydrodynamic models of current and predicted conditions to provide key abiotic and biotic factors influencing larval movement, recruitment, and on‐reef oyster vital rates would assist in balancing the goals of conservation, restoration, and fisheries management of this foundational estuarine species. Impact statementManaging fisheries species of conservation, production, and habitat value relies increasingly on the development of numerical models. We develop a tiered conceptual ecosystem model to guide model development for the eastern oyster and to highlight key uncertainties in vital rates and outcomes. This tiered approach provides a flexible framework to guide numerical model development, and highlight key uncertainties influencing modeled outputs. [ABSTRACT FROM AUTHOR]

Context: Data on chondrichthyan (sharks, rays, and chimaeras) populations is largely lacking for many countries and territories in the Indo-Pacific. Aims: This study aims to provide a desktop review and information synthesis of the biodiversity, threats, and conservation of chondrichthyans in the Samoan archipelago (Samoa and American Samoa), focusing on their interactions with fisheries and exploring their social, cultural, and economic values. Methods: This study uses various literature sources, citizen science, and in-country engagement to assemble a review of current available information on chondrichthyans. Key results: A total of 67 chondrichthyans were documented to be present or potentially present in Samoa and American Samoa, consisting of 23 ray species and 44 shark species. Thirty-six of these species were listed in Threatened categories on the International Union for the Conservation of Nature Red List of Threatened Species. A biological productivity analysis conducted for species with sufficient information indicated that the silvertip shark (Carcharhinus albimarginatus), silky shark (Carcharhinus falciformis), bull shark (Carcharhinus leucas), oceanic whitetip (Carcharhinus longimanus), and whitetip reef shark (Triaenodon obesus) had the highest relative productivities. Conclusions: Both Samoa and American Samoa have relatively diverse shark and ray communities with management plans in place to protect chondrichthyans. These include participation in Western and Central Pacific Fisheries Commission initiatives, spatial protections, and community-based management programs. Implications: Current management approaches have the potential to provide significant protection to sharks and rays, however, their effectiveness may be hindered by a lack of proper enforcement, or compliance at the national and community levels. This study provides an insight into the species of Chondrichthyes (sharks, rays, and chimaeras) present in the Samoan archipelago, an overview of their conservation, and the dynamics surrounding their management and social, cultural, and economic importance. It highlights current knowledge gaps and provides a foundation for further research to better understand chondrichthyan biodiversity and conservation. [ABSTRACT FROM AUTHOR]

Though bioaccumulation of pharmaceuticals by aquatic organisms continues to receive scientific attention, the internal disposition of these contaminants among different tissue compartments of fish species has been infrequently investigated, particularly among fish at different trophic positions. We tested a human to fish biological read‐across hypothesis for contaminant disposition by examining tissue‐specific accumulation in three understudied species, longnose gar (Lepisosteus osseus; piscivore), gizzard shad (Dorosoma cepedianum; planktivore/detritivore), and smallmouth buffalo (Ictiobus bubalus; benthivore), from a river influenced by municipal effluent discharge. In addition to surface water, fish plasma, and brain, gill, gonad, liver, and lateral muscle fillet tissues were analyzed via isotope dilution liquid chromatography tandem mass spectrometry. Caffeine and sucralose, two common effluent tracers, were quantitated at low micrograms per liter levels in surface water, while an anticonvulsant, carbamazepine, was observed at levels up to 37 ng/L. The selective serotonin reuptake inhibitors (SSRIs) fluoxetine and sertraline and primary metabolites were detected in at least one tissue of all three species at low micrograms per kilogram concentrations. Within each species, brain and liver of select fish contained the highest levels of SSRIs compared to plasma and other tissues, which is generally consistent with human tissue disposition patterns. However, we observed differential accumulation among specific tissue types and species. For example, mean levels of sertraline in brain and liver tissues were 13.4 µg/kg and 1.5 µg/kg in gizzard shad and 1.3 µg/kg and 7.3 µg/kg in longnose gar, respectively. In contrast, smallmouth buffalo did not consistently accumulate SSRIs to detectable levels. Tissue‐specific eco‐exposome efforts are necessary to understand mechanisms associated with such marked bioaccumulation and internal dispositional differences among freshwater fish species occupying different trophic positions. Environ Toxicol Chem 2024;43:1894–1902. © 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC. [ABSTRACT FROM AUTHOR]

The Ib River is an important tributary of the Mahanadi River. The aim of the present study was to establish a reliable barcoding reference database for fish in Ib River. A total of 134 specimens, belonging to 42 species within 32 genera, 18 families, and 11 orders, were subjected to PCR amplification of the target region of mitochondrial genome and sequenced. The average length of the 134 barcodes was 648 bp. The average K2P distances within species, genera, and families were 0.13, 9.94, and 16.79%, respectively. The average interspecific distance was approximately 76.46 times higher than the mean intraspecific distance. The Barcode Index Number (BIN) discordance report showed that 134 specimens represented 42 BINs, of which 13 were singletons, 29 were taxonomically concordant while no species taxonomically discordant in our dataset. The barcode gap analysis demonstrated that 100% of the fish species examined could be discriminated by DNA barcoding. These results provide new insights into fish diversity in the Ib River and can provide a basis for the development of further studies on fish fauna. [ABSTRACT FROM AUTHOR]

Anthropogenic land use has caused a major crisis to the biodiversity of stream fishes in recent decades, especially with regard to biotic homogenisation. Understanding the response of stream fishes to anthropogenic land use will help to promptly implement effective conservation measures. In this study, we investigated the effects of agriculture on fish diversity in streams in the Wannan Mountains, China. We predicted that agriculture would influence fish diversity by affecting local habitat conditions. The results showed that habitat conditions (e.g. water temperature, water width, water depth) differed significantly between disturbed and reference sites. The disturbed sites had high species richness due to the addition of translocated species outpacing the loss of endemic species. Moreover, fish assemblages showed taxonomic differentiation accompanied by functional homogenisation, which mainly resulted from the addition of translocated species with redundant functional traits. However, the emergence of homogenisation shows a time delay. The biotic differentiation of fish assemblages in agroecosystems is temporary in the Wannan Mountains, and homogenisation may eventually develop as stress intensifies. Thus, it is urgent and necessary to take effective conservation measures to delay or prevent fish assemblages from worsening in agroecosystems before homogenisation develops. [ABSTRACT FROM AUTHOR]

A refugial population of the endangered delta smelt (Hypomesus transpacificus) has been maintained at the Fish Conservation and Culture Laboratory (FCCL) at UC Davis since 2008. Despite intense genetic management, fitness differences between wild and cultured fish have been observed at the FCCL. To investigate the molecular underpinnings of hatchery domestication, we used whole‐genome bisulfite sequencing to quantify epigenetic differences between wild and hatchery‐origin delta smelt. Differentially methylated regions (DMRs) were identified from 104 individuals by comparing the methylation patterns in different generations of hatchery fish (G1, G2, G3) with their wild parents (G0). We discovered a total of 132 significant DMRs (p <.05) between G0 and G1, 132 significant DMRs between G0 and G2, and 201 significant DMRs between G0 and G3. Our results demonstrate substantial differences in methylation patterns emerged between the wild and hatchery‐reared fish in the early generations in the hatchery, with a higher proportion of hypermethylated DMRs in hatchery‐reared fish. The rearing environment was found to be a stronger predictor of individual clustering based on methylation patterns than family, sex or generation. Our study indicates a reinforcement of the epigenetic status with successive generations in the hatchery environment, as evidenced by an increase in methylation in hypermethylated DMRs and a decrease in methylation in hypomethylated DMRs over time. Lastly, our results demonstrated heterogeneity in inherited methylation pattern in families across generations. These insights highlight the long‐term consequences of hatchery practices on the epigenetic landscape, potentially impacting wild fish populations. [ABSTRACT FROM AUTHOR]

Ecological operation of hydraulic engineering is essential for the conservation of fishery resources. Water velocity is known to affect the spawning of fishes delivering drifting eggs. This study aims to explore the effects of water velocity stimulation on the ovarian maturation and antioxidant capacity of adult grass carp (Ctenopharyngodon idellus) through laboratory experiments in order to understand the physiological mechanism underlying the response of natural reproduction to ecological flows. We examined the histology, sex hormones and vitellogenin (VTG) concentrations of ovary, and the transcripts of key genes in the hypothalamus-pituitary-gonad (HPG) axis, as well as the antioxidant activities of ovary and liver in grass carp. The results showed that although there was no discernible difference on the ovarian development characteristics of grass carp under water velocity stimulation, estradiol, testosterone, progesterone, 17a, 20bdihydroxy- 4-pregnen-3-one (17a, 20b-DHP), and VTG concentrations were elevated, which was related to the transcriptional regulation of the HPG axis genes. The gene expression levels (gnrh2, fshb, lhb, cga, hsd20b, hsd17b3, and vtg) in the HPG axis were significantly elevated under water velocity stimulation, while those of hsd3b1, cyp17a1, cyp19a1a, hsd17b1, star, and igf3 were suppressed. In addition, appropriate water velocity stimulation could enhance body health status by increasing the activities of antioxidant enzymes in the ovary and liver. The results of this study provide the fundamental knowledge and data support for ecological operation of hydropower projects and river ecological restoration. [ABSTRACT FROM AUTHOR]

Incidental capture of non-target species poses a pervasive threat to many marine species, with sometimes devastating consequences for both fisheries and conservation efforts. Because of the well-known importance of vocalizations in cetaceans, acoustic deterrents have been extensively used for these species. In contrast, acoustic communication for sea turtles has been considered negligible, and this question has been largely unexplored. Addressing this challenge therefore requires a comprehensive understanding of sea turtles' responses to sensory signals. In this study, we scrutinized the avenue of auditory cues, specifically the natural sounds produced by green turtles (Chelonia mydas) in Martinique, as a potential tool to reduce bycatch. We recorded 10 sounds produced by green turtles and identified those that appear to correspond to alerts, flight or social contact between individuals. Subsequently, these turtle sounds—as well synthetic and natural (earthquake) sounds—were presented to turtles in known foraging areas to assess the behavioral response of green turtles to these sounds. Our data highlighted that the playback of sounds produced by sea turtles was associated with alert or increased the vigilance of individuals. This therefore suggests novel opportunities for using sea turtle sounds to deter them from fishing gear or other potentially harmful areas, and highlights the potential of our research to improve sea turtles populations' conservation. [ABSTRACT FROM AUTHOR]

The northwestern Antarctic Peninsula is an important spawning, recruitment, and overwintering ground for Antarctic krill. The region is warming rapidly, and the current impacts of climate and environmental variability on the reproductive cycle of krill remain unclear. Here, we examine the reproductive stage of female krill in the austral winter from 2012 to 2016 in relation to climate and environmental data to assess what factors influence the timing of reproductive development. We observed significant interannual variability in the degree of maturation in female krill, ranging from 48% of female krill measured at a station in 2016 to a maximum of 94% of female krill measured at a station in 2014. On average, across all five years, three-quarters of the female krill sampled were in the stage known as previtellogenesis, the point at which the onset of sexual maturity begins. The preceding spring, summer, and autumn Southern Annular Mode and the Multivariate El Niño Index explained most of the variance in the data and indicated a strong, preconditioning storm-related effect on environmental conditions leading up to winter, affecting krill maturation status at the end of the winter season. Results from our study can be used to improve krill population models that are necessary for the management of the krill fishery and for conservation at the northwestern Antarctic Peninsula. [ABSTRACT FROM AUTHOR]

Simple Summary: Loliolus spp., such as Loliolus beka (Sasaki, 1929) and Loliolus uyii (Wakiya and Ishikawa, 1921), represent a dominant fishing bycatch in the East China Sea. However, their seasonal–spatial distribution characteristics are unclear. Here, the generalized linear mixed-effects model sdmTMB was used to evaluate ways of handling merged distribution data for L. beka and L. uyii to predict the variation in their spatial distributions under different climate change scenarios. Model predictions were validated using cross-validation, while model performance was assessed using T-tests. We speculated that the range and density of both species will vary over time, with some areas in the mid-East China Sea becoming potential habitats. In addition, we assumed that individuals of both species in the northern survey area might migrate to the northern Yellow Sea and Bohai Sea to spawn, whereas those in the central and southern Yellow Sea might migrate to coastal areas. During autumn, newborn larvae in the northern survey area would migrate to the southern Yellow Sea, whereas those in the central and southern areas would gradually migrate to offshore areas, resulting in a distribution ranging from coastal sea areas to the central survey area. Thus, this study provides novel insights into modeling habitat distributions for data-limited species and theoretical support for adapting fisheries resource management to climate change. Global climate change profoundly impacts the East China Sea ecosystem and poses a major challenge to fishery management in this region. In addition, closely related species with low catches are often not distinguished in fishery production and relevant data are commonly merged in statistics and fishing logbooks, making it challenging to accurately predict their habitat distribution range. Here, merged fisheries-independent data of the closely related squid Loliolus beka (Sasaki, 1929) and Loliolus uyii (Wakiya and Ishikawa, 1921) were used to explore the construction and prediction performance of species distribution models. Data in 2018 to 2019 from the southern Yellow and East China Seas were used to identify the seasonal–spatial distribution characteristics of both species, revealing a boundary line at 29.00° N for L. uyii during the autumn, with the highest average individual weight occurring during the summer, with both larvae and juveniles occurring during the autumn. Thus, the life history of L. uyii can be divided into winter–spring nursery and summer–autumn spawning periods. L. beka showed a preference for inshore areas (15–60 m) during the summer and offshore areas (32.00–78.00 m) during the winter. High-value areas of both species included inshore areas of the southern Yellow and mid-East China Seas during the autumn, enlarging during the spring to include central areas of the survey region, before significantly decreasing during the summer. Therefore, this study provides both a novel perspective for modeling biological habitat distribution with limited data and a scientific basis for the adjustment of fishery resource management and conservation measures in the context of climate change. [ABSTRACT FROM AUTHOR]

The expansion of marine protected areas (MPAs) is a core focus of global conservation efforts, with the "30x30" initiative to protect 30% of the ocean by 2030 serving as a prominent example of this trend. We consider a series of proposed MPA network expansions of various sizes, and we forecast the impact this increase in protection would have on global patterns of fishing effort. We do so by building a predictive machine learning model trained on a global dataset of satellite-based fishing vessel monitoring data, current MPA locations, and spatiotemporal environmental, geographic, political, and economic features. We then use this model to predict future fishing effort under various MPA expansion scenarios compared to a business-as-usual counterfactual scenario that includes no new MPAs. The difference between these scenarios represents the predicted change in fishing effort associated with MPA expansion. We find that regardless of the MPA network objectives or size, fishing effort would decrease inside the MPAs, though by much less than 100%. Moreover, we find that the reduction in fishing effort inside MPAs does not simply redistribute outside--rather, fishing effort outside MPAs would also decline. The overall magnitude of the predicted decrease in global fishing effort principally depends on where networks are placed in relation to existing fishing effort. MPA expansion will lead to a global redistribution of fishing effort that should be accounted for in network design, implementation, and impact evaluation. [ABSTRACT FROM AUTHOR]

Lotic fish species distributions are frequently predicted using remotely sensed habitat variables that characterize the adjacent landscape and serve as proxies for instream habitat. Recent advancements in statistical methodology, however, allow for leveraging fish assemblage data when predicting distributions. This is important because assemblage composition likely provides better information about instream habitat compared to landscape-derived metrics and therefore may improve predictions. To better understand the value of using multi-species fish data in species distribution modeling, we fit two conditional random fields (CRF) models to quantify the relative importance of fish assemblage co-occurrence, landscape-derived habitat variables, and interactions between these two predictor groups (i.e., effects of co-occurrence could be context-dependent) at over 1200 stream catchments in Pennsylvania, USA. We first compared predictive performance of CRF models against traditionally used single-species logistic regressions (generalized linear models; GLMs) and found that inclusion of fish assemblage data often improved predictive performance. The multi-species CRF models performed significantly better at predicting occurrence for 63% of species with an average percent increase in AUC of 25% compared to GLMs. Furthermore, the CRF identified species co-occurrences as more informative, and thus relatively more important, at predicting occurrence than the other effect types. The CRF also suggested that allowing these biotic effects to be context-dependent was important for predicting occurrence of many species. These findings illustrate the value of fish assemblage data for landscape-scale species distribution modeling and leveraging this information can improve predictions and inferences to help inform the management and conservation of freshwater fishes. [ABSTRACT FROM AUTHOR]

Pacific salmon, the signature species of the Pacific Northwest, have declined across their range for well over a century, due to a myriad of human-caused effects on their habitat and the fish themselves. Restoration efforts--some successful, some halting--began in earnest in the late 20th century, with considerable attention focused on the Columbia Basin, where historically salmon runs were crippled by a large interconnected hydroelectric system of federal and non-federal dams. In the 1980 Northwest Power Act, Congress created an interstate agency, the Northwest Power and Conservation Council, with access to a substantial amount of ratepayer dollars; the agency has chosen to expend those dollars principally for habitat rehabilitation and hatchery production. Generic federal laws like the Clean Water Act and the Endangered Species Act have provided some levers to modify dam operations to benefit fish and driven better protections for salmon throughout the Northwest. The relicensing requirements of the Federal Power Act, coupled with that law's fish protection provisions, have led to several notable dam removals. Significant restoration in Puget Sound watershed is underway due to a judicial decision finding that barrier road culverts violate treaty fishing rights, an interpretation that holds potential to foster salmon habitat improvement measures throughout the Northwest. Surveying events from Alaska's Bristol Bay in the north to the Klamath River along the Oregon-California border in the south, we explain how the law has--and must--play a key role in efforts to save salmon. Although the importance of particular laws varies from basin to basin--as does their effectiveness--some significant restoration is underway despite major unanswered questions such as the fate of the lower Snake River dams. The institution of tribal co-management programs, especially along the Oregon coast, provide an especially significant restoration tool if this development can be replicated across salmon country. The addition of tribal sovereigns into decision-making is likely to improve salmon protection and restoration wherever comanagement programs exist. Improved management will be a prerequisite if Pacific salmon are to recover in a climate-challenged world that threatens the existence of many runs. But to a large extent, restoring historic fish runs will require federal policies and leadership that have not always been present. As the first quarter of the 21st century draws to a close, salmon saving efforts are proceeding on a variety of fronts with some promising results, but the future of many salmon runs is clouded by the threat of climate change and a national ambivalence to confronting its challenges with a muscular response. [ABSTRACT FROM AUTHOR]

Fish migrate for varied reasons, including to avoid predators and to access feeding, spawning, and nursery habitats, behaviors that enhance their survival and reproductive rates. However, the migratory ecology of many important fishes, especially those in river–floodplain ecosystems, remains poorly understood. One fish of the Amazon Basin whose migratory behavior is poorly understood is the catfish Pseudoplatystoma fasciatum. Here, we used otolith elemental microchemistry to characterize the migration ecology of P. fasciatum in the Amazon Basin. The main research questions of this study were: (1) does P. fasciatum move between waters with different Sr isotopic signatures (87Sr/86Sr) and chemical compositions? (2) What distance do they migrate? (3) Is the migration of P. fasciatum related to age? And (4) does P. fasciatum migrate mainly upstream, downstream, or in both directions? We assessed whether P. fasciatum migrates between waters with different 87Sr/86Sr values, comparing the Sr isotopic signature of otolith transects of each individual with the range of Sr isotopic signatures within the respective rivers. We found that 34% of the 71 fish analyzed migrated between rivers with different Sr isotopic signatures and 66% did not. The mean migration distance migrated was 126 km, with most specimens migrating between 72 and 237 km. Apparently, no fish of age one or age six or older migrated. All fish that migrated were between two and five years of age, with 20% of the specimens that migrated being two years old, 40% three years old, 30% four years old, and 20% five years old. Sixty-six percent of all individuals that migrated between rivers with different Sr signatures did so bidirectionally, while 33% moved unidirectionally. According to our definition of homing behavior in which fish migrated back to the same river where they were born, 41% of all fish that migrated displayed apparent homing behavior. Our findings provide insights into the migratory ecology of P. fasciatum, corroborating and refining knowledge reported in the literature. Our results on the migratory ecology of P. fasciatum have implications for sustainable fisheries conservation and management: conserving P. fasciatum requires habitat maintenance and suitable fishing practices in spawning and nursery habitats, and managers must consider large geographic areas for effective fishery management and conservation. [ABSTRACT FROM AUTHOR]

Scientists increasingly draw on fishers' ecological knowledge (FEK) to gain a better understanding of fish biology and ecology, and inform options for fisheries management. We report on a study of FEK among fishers along the Lower Ucayali River in Peru, a region of exceptional productivity and diversity, which is also a major supplier of fish to the largest city in the Peruvian Amazon. Given a lack of available scientific information on stock status, we sought to identify temporal changes in the composition and size of exploited species by interviewing fishers from 18 communities who vary in years of fishing experience since the mid‐1950s. We develop four FEK‐based indicators to assess changes in the fish assemblage and compare findings with landings data. We find an intensification of fishing gear deployed over time and spatiotemporal shifts in the fish assemblage and reported declines in species weight, which point to a fishing‐down process with declines across multiple species. This finding is reflected in a shifting baseline among our participants, whereby younger generations of fishers have different expectations regarding the distribution and size of species. Our study points to the importance of spillover effects from the nearby Pacaya‐Samira National Reserve and community initiatives to support the regional fishery. Reference to fishers' knowledge also suggests that species decline is likely underreported in aggregated landings data. Despite the dynamism and diversity of Amazonian floodplain fisheries, simple FEK‐based indicators can provide useful information for understanding fishing‐induced changes in the fish assemblage. Fishers hold valuable knowledge for fishery management and conservation initiatives in the region. [ABSTRACT FROM AUTHOR]

In order to investigate the relationship between the surface distribution of fish larvae and juveniles and environmental factors in the Philippine Sea in summer, surface horizontal trawl surveys were conducted with large larvae and juvenile fish nets (diameter 1.3 m, mesh 0.5 mm) at 50 sampling stations in the Philippine Sea (11°N-19°N, 129°E-138°E) during the summer of 2022. A total of 38 159 fish larvae and juveniles, belonging to 14 orders, 21 families, and 56 species were collected. The dominant species in the daytime collection were Thunnus albacares and Encrasicholina punctifer, while the dominant species in the nighttime collection was Encrasicholina punctifer, so the co-dominant species was Encrasicholina punctifer, which accounted for 97.05% of the total number of samples collected. The total mean density of fish larvae and juveniles at each station was 292.43 ind./1 000 m³, with a mean density of 17.61 ind./1 000 m³ collected during the daytime and 526.54 ind./1 000 m³ collected during the nighttime, indicating significant differences in diel distribution. The stations with higher densities were mainly located in the sea near 15 N, and all sample were collected at night. Canonical correlation analysis showed that the environmental factors affecting the distribution of fish larvae and juveniles were, in descending order, sea surface salinity, sea surface temperature, and dissolved oxygen. The distribution of the dominant species Encrasicholina punctifer was mainly influenced by sea surface salinity and dissolved oxygen. The study shows that the fish larvae and juveniles in the Philippine Sea have a rich species composition with uneven surface distribution and significant differences in diel distribution. This study can provide a scientific basis for the assessment, conservation and utilization of fishery resources in the Philippine Sea. [ABSTRACT FROM AUTHOR]

The hemicultrine fishes are a group of small‐sized cyprinids, widely distributed but endemic to East Asian rivers and lakes. Till now, the taxonomic boundaries and relationships within this group remain poorly explored. In the present study, we study the phylogeny of this group, providing suggestions for classification of the hemicultrine group. Using two mitochondrial and three nuclear genes, and samples representing all genera, our results showed that the group consists of seven major lineages, of which four (Hemiculterella, Hainania, Pseudolaubuca, and Anabarilius) were monophyletic and three (Hemiculter, Toxabramis, and Pseudohemiculter) were not. Based on the phylogenetic tree, we redefined the genera. We revive the genus Siniichthys, which has three species, Siniichthys bleekeri, Siniichthys lucidus, and S. varpachovskii, that were previously treated as members of the genus Hemiculter but showed distant relationships to the genus Hemiculter in our phylogenetic tree. With the new results, a diagnostic key for clades of the hemicultrine group is provided. Furthermore, we provide more detailed information on diagnostic features of the recently described species Hemiculter yungaoi (Vasil'eva et al., 2022). This work will facilitate future systematic studies, pave the way for evolutionary studies, and provide valuable information for the urgent conservation of hemicultrine fishes. [ABSTRACT FROM AUTHOR]

The Yarlung Zangbo River is a river with abundant hydropower resources but fragile biodiversity in China. As an important benchmark for both research and ecological management, there is still a lack of knowledge about the swimming ability of fishes in the Yarlung Zangbo River. The induced flow velocity (Uind), critical swimming speed (Ucrit), and burst swimming speed (Uburst) of five Schizothoracinae species were tested in this study. Relative swimming ability related to body length and body shape was calculated. The results indicated that the average absolute swimming speeds (Uind‐a, Ucrit‐a, and Uburst‐a) of all the experimental fish were 10.20 ± 0.01, 57.58 ± 3.28, and 69.54 ± 2.94 cm/s, respectively, and the corresponding relative Uind, Ucrit, and Uburst related to body length (Uind‐l, Ucrit‐l, Uburst‐l) were 1.15 ± 0.07, 5.04 ± 0.26, and 7.23 ± 0.28 BL/s, respectively. Moreover, relative Uind, Ucrit, and Uburst related to body shape (Uind‐s, Ucrit‐s, and Uburst‐s) were 0.80 ± 0.13, 2.49 ± 0.51, and 4.32 ± 0.57 cm−2/s, respectively. No significantly differences in relative swimming speeds existed among five species. Only Oxygymnocypris stewartii was significantly weaker in Uburst‐s than Schizothorax o'connori. The body shape showed a stronger relationship with swimming speed than the body length did. Schizothoracinae fish in the Yarlung Zangbo River basin are less sensitive to the water flow and performed weaker Ucrit and Uburst compared to those in the Yangtze River basin, indicating that Schizothoracinae fish in the Yarlung Zangbo River may be more susceptible to threats from environmental changes. The paper enriched the research on the swimming ability of Schizothoracinae fishes and provided efficient data for the fish conservation in the Yarlung Zangbo River. [ABSTRACT FROM AUTHOR]

Simple Summary: The Argentine hake (Merluccius hubbsi) is a significant fish species in the Southwest Atlantic, both economically and ecologically. These fish often host Anisakidae larvae, which are common parasites. Despite their prevalence, the specific nutritional relationships between these parasites and their host are not well understood. This study uses stable isotope techniques to investigate these relationships by analyzing the carbon and nitrogen compositions in different tissues of the hake and comparing them to those in the parasites. The results show significant differences, indicating that the parasites primarily obtain their nutrients from the hake's stomach but also from other tissues. This study provides new insights into the complex nutritional interactions between the M. hubbsi and Anisakidae parasites, which can help improve the management and conservation of this important fish species. The Argentine hake (Merluccius hubbsi) is a vital fishery species in the Southwest Atlantic, recognized for its substantial economic importance. Previous studies have identified Anisakidae larvae as common parasites of M. hubbsi. However, the nutritional relationships between these parasites and their host remain poorly understood. This study employs stable isotope techniques to investigate the specific nutritional relationships between Anisakidae larvae and different tissues of M. hubbsi. The findings reveal notable differences in δ13C and δ15N compositions between the parasites and their host. The lower δ13C values in parasites compared to host tissues indicate the utilization of different carbon sources. The δ15N values of the parasites partially overlap with those of the host's stomach, indicating that the parasites primarily derive nutrients from the host's stomach. Nutritional niche indicators show that parasites have a broad carbon range (CR) and nitrogen range (NR), suggesting a high diversity in nutritional sources. The trophic discrimination factor (ΔTDF), which represents the difference in stable isotope values between host tissues and parasites, was analyzed for both δ13C and δ15N. The Δ T D F δ 13 C between the host liver and the parasites showed the greatest variation, indicating a strong dependence of the parasites on the liver's carbon sources. In contrast, variations in Δ T D F δ 15 N between host tissues and parasites were minimal. Analyzing ΔTDF across different stages of gonadal maturity in the host fish indicates that, as the gonads of the host fish mature, Δ T D F δ 13 C between host tissues and parasites significantly decreases (p < 0.01). The Kruskal–Wallis test showed significant differences in Δ T D F δ 13 C values among different parasite infection levels in muscle, liver, and stomach tissues, while no significant differences were found for Δ T D F δ 15 N values. These findings offer valuable insights into the nutritional relationships between parasites and hosts, aiding in a better understanding of the growth conditions and habitats of M. hubbsi. [ABSTRACT FROM AUTHOR]

To better understand stream‐fish sensitivity to fine sediment, we documented assemblage‐wide responses by selected traits along a sedimentation gradient. We then discuss the management implications of these 'dose–response' relations in the contexts of biotic assessments and conservation of sediment‐sensitive species. We identified a spatial gradient in sediment deposition among streams within the upper Piedmont of the Roanoke River basin in North Carolina and Virginia. We assessed fine‐sediment sensitivity of 81 species based on eight species traits stratified by four attributes: food preference, feeding location, spawning substrate and spawning behaviour. We then ranked each trait and scored each species with respect to its sediment sensitivity. Using data from electrofishing surveys during 2018–2019, we calculated proportional abundances of traits observed at 30 sites throughout the study area and grouped species by their aggregate sensitivity scores. We assessed relations between embeddedness and silt cover and occurrences of species and traits using a combination of regression and ordination approaches. All traits tested responded to embeddedness or silt cover, or both. Feeding traits exhibited the strongest responses to embeddedness, while reproductive traits exhibited the strongest responses to silt cover. Our findings indicate that negative responses of the probability of presence for high‐sensitivity traits to embeddedness and silt cover were linear, with no apparent thresholds. Additionally, proportional abundances of species with multiple high‐sensitivity traits were inversely related to embeddedness and silt cover. Overall, our findings regarding population‐level responses to sedimentation were consistent with our findings for trait‐specific responses. Our analysis of species sensitivity to fine sediment corroborated the patterns we saw in our trait‐specific analyses, indicating that population responses to sedimentation can be predicted from combinations of species traits. The 'dose–response' relations we documented may be applicable to managing sediment impacts on fishes, especially in the contexts of biotic assessments and conservation of sediment‐sensitive species. [ABSTRACT FROM AUTHOR]

The increasing global demand for marine resources raises concerns about sustainable resource management and biodiversity conservation. Spatial closures, such as marine protected areas, can be valuable tools for maintaining and restoring exploited populations. When these spatial closures adopt a dynamic nature being adapted to the changing environment, they can effectively account for factors such as shifting species distributions, which enhances their potential to achieve ecological and socio‐economic objectives. Here, we adapted a decision‐support tool (the software Marxan), typically used for selecting static and permanent areas, to produce management recommendations that integrate permanent and temporal closures to fisheries. Our aim was to compare the outputs of a static network of permanent no‐take reserves with four other dynamic scenarios, including permanent and temporal closures that account for seasonal variations in the populations of species. All scenarios prioritized sites for the conservation of one of the most valuable European fishing stocks, the Norway lobster (Nephrops norvegicus). Additionally, we considered 12 other commercially exploited species captured by the Norway lobster fishery. The assessed outputs included retained biomass, area extent, closure type (permanent and seasonal) and opportunity costs within each scenario. We observed that all dynamic scenarios required fewer management areas permanently closed than the static scenario. This resulted in a lower opportunity cost for fisheries but also a higher capacity for biodiversity conservation. Therefore, complementing permanent with temporal closures could enhance biodiversity conservation and fisheries management. The novel dynamic planning method presented here could be applicable to other species, ecosystems and socio‐economic contexts. [ABSTRACT FROM AUTHOR]

The water quality of Narmada River is decreasing down and the pollution is increasing as the length of time is increasing. It was also visually observed that Narmada River water is getting polluted due to anthropogenic activities of the human beings, such as bathing, cleaning clothes, religious wastes dumped into the River, vehicles washing, used pesticides containers nearby River and sewage wastes mixed with River water. Physicochemical parameters of three different sites viz., Bhedaghat, Lamhetaghat and Temar of Narmada River Jabalpur were analyzed along with Fish farm Bargi Nagar. Physicochemical parameters like temperature, pH, dissolved oxygen (DO), CO2 and total alkalinity were studied during June 2023 to November 2023. During the experimental period the water temperature, transparency, DO, pH, total alkalinity and free CO2 were recorded in the range of 22.5 to 30.2°C, 10.11 to 39.34 cm, 5.5 to 8.5 mg/l, 8 to 8.9, 160 to 220 mg/l and 3.8 to 5.9 mg/l, respectively. Results of the physicochemical parameters of present study indicated the poor water quality of Bhedaghat and Lamhetaghat as compared to Temar site of Narmada River due to different anthropogenic activities. This is the preliminary study regarding the conservation of state fish Mahseer of Madhya Pradesh. [ABSTRACT FROM AUTHOR]

Rhododendron arboreum, belonging to the Ericaceae family, is primarily distinguished by its vivid red or light pink flowers. The flower is often known as "Lali Gurans" in Nepali and is recognized as the official flower of Nepal. Rhododendron flowers have traditionally been used to cure various human ailments including blood dysentery, headache, asthma, cough, stomachache, fever, inflammation and fungal infections. Moreover, it has medicinal and pharmacological importance. The present study aimed to investigate the beneficial effects of dietary laligurans flower as the growth promotor and immunostimulant in common carp (Cyprinus carpio) fingerlings. Rhododendron flowers taken from the Phulchowki hills of Kathmandu Valley were taxonomically identified by the National Herbarium Center, Govt. of Nepal following ethanol (70%) extract (LGE) and plain powder (LGP) were prepared. There was a total of 7 diets used in the study in which the control diet (T1) did not have any supplementation. The other diets 0.2% (T2), 0.4% (T3), 0.8% (T4) and 1.6% (T5) were supplemented with ethanol extract (LGE) while 0.2% (T6) and 0.4% (T7) were with dry powder (LGP). The experiment was specifically built as a recirculating aquaculture system and was carried out at the Central Fisheries Promotion and Conservation Center (CFPCC), Government of Nepal located in Balaju, Kathmandu. The aquaria were divided into 7 diets, with 3 replicates for each diet hence, fingerlings of common carp (Cyprinus carpio) weighing 2.43±0.21g allocated to 21 glass aquaria randomly. The fish were provided with food equivalent to 5% of their body weight and the sampling was conducted after a period of 90 days of feeding experiments. Statistically significant growth (p< 0.05) was seen in all the treated fish. However, carp fed with LGE performed better and the maximum amount of growth was obtained in carp fed with the 0.8% (T4) diet. The levels of total protein, albumin and globulin demonstrated an upward trend, but the levels of SGOT, SGPT and ALP showed a downward trend when compared to the control and LGP-treated diet. The haematological parameters of the fish given a T4 treated diet were within the normal range, however the levels of hemoglobin (Hb) and hematocrit (PCV) were elevated. Based on the evidence, it is advised that aqua culturists use the ethanol extract of laligurans flower to promote fish growth and improve the socioeconomic activities of farmers. [ABSTRACT FROM AUTHOR]

Despite significant advancements in ichthyoplankton collection and data processing, challenges persist in the taxonomic identification of these organisms, particularly their eggs. To overcome these challenges, a novel technique has been developed to facilitate the identification of live eggs collected directly in wild. This user-friendly technique includes the collection, processing of the material, and field incubation. Sampling must be conducted using a pelagic net towed at low speed, preferably during early evening. The material processing involves pre-sorting and sorting to remove eggs and larvae. The separated eggs, kept in an aerated bowl, can be identified based on their morphological and meristic characteristics. Unidentified eggs can be placed in plastic bags with oxygen and incubated directly in the aquatic environment for 48–72 h. After this incubation period, the hatched larvae at the yolk-sac or preflexion stage, are identified to the lowest possible taxonomic level. Depending on the study's purpose, hatched larvae and field-collected larvae can be transported to research centers for further development, released back into the natural environment, or fixed to complete the collection. The application of this technique supports management and monitoring programs by identifying spawning areas through egg identification, forming broodstock, and replenishing threatened species, thereby enhancing scientific collections of ichthyoplankton. Additionally, it reduces mortality in ichthyoplankton techniques, including endangered species. Therefore, we believe that this novel taxonomic technique for identifying live ichthyoplankton represents a paradigm shift in the monitoring, management, and conservation of fish, as well as in ecological stewardship and advances in this area of research. [ABSTRACT FROM AUTHOR]

Understanding complex river floodplains is critical to conserve species of fish and their ecological functions. In 2011 through 2013, longitudinal gradients in fish assemblage were investigated in the Willamette River in western United States. Of 36,586 individual fish collected, 93% were native and 7% non‐native. The best predictors of fishes collected with a boat electrofisher were percent embeddedness, macrophytes, longitudinal river distance, average depth, and velocity. Habitat type (mainstem or slough) was also a significant predictor. The best predictor of fishes collected in nearshore habitats with a backpack electrofisher were longitudinal river distance, velocity, and percent embeddedness. Fish communities differed significantly between mainstem and slough habitat. Overall, 25 of 40 species had high fidelities to mainstem or slough habitats. Native species showed a high fidelity to both mainstem and slough habitats while non‐native species were significantly related only to slough habitats. Environmental characteristics strongly influenced fish assemblage structure in this large floodplain river. Maintaining and restoring mainstem and off‐channel habitats are critical for maximizing native species resilience in the face of non‐native species encroachment and a changing environment. Restoring the natural flow regime to the degree possible is needed to increase connectivity between the floodplain and mainstem and provide thermal and flood refuges for native fishes. Understanding habitat relationships provides essential context for fish conservation and management by resource agencies and landowners. [ABSTRACT FROM AUTHOR]

Identifying a fish's artificial or natural origin is crucial for stock enhancement assessments. In this study, we collected specimens of hatchery (including the early fry, reared, and released juveniles) and wild mangrove snapper Lutjanus argentimaculatus to explore the feasibility of using δ13C and δ15N values in scales as a non-lethal alternative to muscle tissues for discriminating between hatchery and wild origins. The results showed scales generally enriched in δ13C value and relatively consistent in δ15N value compared to muscle. Significant correlations were found between the two tissues for both δ13C and δ15N values (R2 = 0.80–0.88). Based on the isotopic composition of the scale core, individuals with different origins could be effectively discriminated, achieving a classification success rate of 77.6%. The random forest analysis revealed that a δ13C value of −15.8‰ could be a reference for determining the hatchery and wild origins of mangrove snapper. This study provides an isotopic approach for assessing the benefit of stock enrichment in mangrove snapper. It highlights the importance of regular sampling and scales analysis to expand fishery management and conservation practices. [ABSTRACT FROM AUTHOR]

The population dynamics of Polititapes aureus from Tunisia were investigated monthly during a one-year period (2018). The possible future commercial benefits of the species as a significant resource of artisanal fisheries require better knowledge of its population dynamics. This study provides the first insight into population parameters by investigating its population structure, growth, mortality, and exploitation rate. Allometric relationships between body size and length were determined. The shell length/ total weight ratio indicated a positive allometric growth and was expressed as TW = 0.0002 SL3.103. Length frequency data were analyzed to estimate population parameters using FiSAT ΙΙ software. P. aureus showed lower growth rate (K = 0.46 yr–1) and asymptotic length (L∞ = 38.80) compared to those obtained for other bivalve species (mean values: K = 0.61 and L∞ = 55.02). Longevity (Tmax) and the growth performance index (φ') were 7.95 yr-1 and 2.84, respectively. Total mortality (Z) was estimated from the length-converted catch curve at 0.85 yr-1 and fishing mortality (F) at 0.03 yr-1. Both values of natural mortality (M = 0.82 yr-1) derived from bivalve literature and based on Pauly's (1980) empirical equation (M = 0.83 yr-1) developed for fish were comparable. The most intensive growth occurred during the first three years. The data presented herein are crucial for appropriate fisheries management and conservation of clams. [ABSTRACT FROM AUTHOR]

This qualitative investigation examines fish conservation practices in the community water resources of three northeastern Thai provinces. Data was gathered from documentary review and field study, through observation, interviews, and focus group discussions. The findings revealed that fish resources are decreasing in Northeastern Thai communities. This is due to a combination of factors, including unsystematic conservation methods and negative human impact. In acknowledging the ecocontextual nature of Thai Buddhism, this investigation argues a case for the adoption of Buddhist principles toward environmentalism as a means for more sustainable and successful fish conservation. The paper outlines eight key religious principles compatible with conservation approaches and recommends their inclusion in government policy. [ABSTRACT FROM AUTHOR]

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Effective management and conservation of fishes requires understanding habitat use across multiple life stages while ensuring necessary habitats are both available and accessible. Tributary habitats may play an important role in recruitment and dispersal of fishes in anthropogenically modified rivers such as the Mississippi and Illinois Rivers of the Midwest U.S.A. Identifying source locations that contribute to recruitment of fish populations can determine the importance of connectivity within river networks and pinpoint critical habitats that sustain fish populations. In the Upper Mississippi River System (UMRS), the environments that fish use in early life stages (i.e., natal origin) can be identified using otolith trace element analysis due to stability and distinctness in water chemistry (strontium: calcium [Sr:Ca]) among water bodies that is reflected in otoliths.Here, we used trace element analysis to determine natal origin of six small‐bodied fishes including bullhead minnow (Pimephales vigilax), emerald shiner (Notropis atherinoides), gizzard shad (Dorosoma cepedianum), bluegill (Lepomis macrochirus), orangespotted sunfish (Lepomis humilis), and yellow perch (Perca flavescens) across six reaches of the UMRS (Pools 4, 8, 13, 26, the Open River of the Middle Mississippi River, and the La Grange Pool of the Illinois River). Otolith core Sr:Ca for fishes was quantified using laser ablation inductively coupled plasma mass spectrometry. Using the resulting Sr:Ca chemical signatures of otolith cores, natal origin (tributary, immigrant, or potential resident) was determined for individual fish based on family‐specific relationships between otolith and water chemistries.We found that all species originated from tributaries and other reaches (i.e., were immigrants) to varying extents, which acted as evidence for network connectivity. Specifically, tributaries contributed up to 48% of individuals at a given reach. In certain reaches, Pool 26 and the Open River reach, up to 80% of individuals in a species immigrated from another mainstem river reach. Network connectivity was also important in both upstream and downstream directions. Contributions from network connectivity varied among species: bullhead minnow used less whereas orangespotted sunfish used more network connectivity than when all species were combined. Further, the use of network connectivity varied spatially where individuals captured in Pool 8 and the La Grange Pool less often and those from Pool 26 and the Open River more often originated from network connectivity compared to the whole assemblage across reaches.These results indicate that species' life history traits probably interacted with the physical environment, which differs spatially, to yield observed recruitment source patterns. Our results show that network connectivity contributes to established assemblages of native small‐bodied fishes throughout the UMRS and underscore the role of interjurisdictional management in maintaining network connectivity to sustain fish populations. [ABSTRACT FROM AUTHOR]

Anthropogenically driven flow intermittency is increasing in freshwater streams, with important implications for the management and conservation of aquatic ecosystems. Because most freshwater fishes are mobile, they are expected to emigrate from intermittent reaches, but this may not be true in streams transitioning from perennial to intermittent. Here, we attempt to determine if riverine fishes vacate drying reaches before intermittency or remain in local refuges.We implemented a controlled, in situ experimental flow reduction resulting in intermittency, reducing flows from ~1.0 to 0 m3/s over a 3‐week period. We monitored fish and fish‐habitat changes over a 5‐week period before, during and after flow reductions.During flow reductions, total wetted habitat was ultimately reduced by 91%. Habitat loss over time was not equal among habitat types: pool habitat increased slightly as run habit was lost, and backwater and isolated pool habitats were not strongly related to discharge. Likewise, water depth in run habitats decreased faster than other habitats.Only the river carpsucker Carpiodes carpio appeared to move upstream during flow recession; seven other species remained within drying sites. Habitat loss negatively affected fish populations, but at a lower rate than that at which habitat was lost, until sites dried completely. Overall, two species, red shiner Cyprinella lutrensis and western mosquitofish Gambusia affinis, had increased population growth during the study, whereas the remaining species had population declines.Fishes were able to find transient local refuges during flow reductions but did not vacate sites before intermittent conditions. Accounting for lack of emigration from anthropogenic flow‐intermittent reaches will be important for designing conservation actions for fishes threatened by increasing flow intermittency. Creation of refuge habitats may not be effective for widely dispersed species that do not actively seek refuge habitats, unless those habitats support enough individuals to maintain resilience following the intermittent conditions. [ABSTRACT FROM AUTHOR]

Fresh water is essential to human society and the survival of all terrestrial ecosystems. Despite the fact that India possesses a diverse range of fresh water resources, most systems are under pressure from anthropogenic activity, posing major threats to fish diversity. As a result, conservation and management are vital to the interests of all persons, nations, and governments, and thus the current research. Present research work done from November 2021 to October 2022. Approximately 17 species were collected and identified during the study of the Borda dam, belonging to 7 orders, 9 families, and 16 genera. Among them, 5 species were belong to the Order Cypriniformes, and Siluriformes each, 3 species to Order Perciformes, while the Orders Osteoglossiformes, Synbranchiformes, Beloniformes and Cichliformes comprises single species. As a result, the findings of our current study will provide significant information about the diversity of fish fauna in the Borda dam, which will be used in the future for monitoring, fisheries management, and conservation. [ABSTRACT FROM AUTHOR]

Fisheries management and conservation require consideration of fish, habitat, and people. In fisheries science, a growing body of research on human values, perspectives, and behaviours around fish—known as 'human dimensions' research—has emerged from the realization that management and conservation require a better understanding of people. Surveys are a common and versatile tool in human dimensions research, but not all surveys are equal. Large-scale, probabilistic surveys draw random samples from known populations (e.g., all license-holding recreational fishers in a jurisdiction) and represent the 'gold standard' in survey research. However, these surveys may fall short of this standard for various reasons. Surveys using non-probabilistic sampling are also common in human dimensions research. Non-probabilistic surveys are attractive to researchers facing time, cost, and other constraints, but differ notably from their probabilistic counterparts: data from non-probabilistic samples are typically unfit for population estimates and other inferences due their uncertain representativeness. Nonetheless, a wealth of research with non-probabilistic data within and outside of fisheries (e.g., in health sciences) suggests that these methods have valid applications and advantages in some contexts. We reviewed the literature on non-probabilistic surveys and sampling in the human dimensions of fisheries, and explored seminal literature from other thematic areas where such methods are common, to better understand their strengths, weaknesses, and applications relative to probabilistic methods. Here, we describe (1) how researchers have used non-probabilistic methods to study the human dimensions of fisheries, (2) how mismatching research questions, objectives, and methods can produce 'awkward surveys,' and (3) how researchers can use non-probabilistic surveys in ways that invoke their methodological strengths. While uncertain representativeness may limit the utility of non-probabilistic data in some contexts, non-probabilistic methods are time- and cost-effective, and have distinct advantages in studies of niche groups and phenomena, emergent or understudied phenomena, and in supplementary roles. [ABSTRACT FROM AUTHOR]

Hydropower plants (HPPs) create barriers across rivers and fragment aquatic ecosystems, river reaches and habitats. The reservoirs they create slow the flowing water and convert the riverine into lacustrine ecosystems. The barriers created by HPPs interrupt the seasonal migrations of many fish species, while the reservoirs drive away fish species that are dependent on flowing water habitats. This paper assesses the distribution of fish species in the 3S rivers—Sekong, Sesan and Sre Pok, in Cambodia, Laos and Viet Nam—using IUCN Red List-assessed species distribution by HydroBasin Level 8 from the freshwater reports of the Integrated Biodiversity Assessment Tool (IBAT) and their connectivity with the Mekong. There are currently 61 commissioned dams in the 3S basins and a further 2 under construction, 23 of which are larger than the 30 MW installed capacity. A further 24 HPPs are proposed or planned in these basins. The changes in connectivity caused by the dams are measured by adapting the River Class Connectivity Index (RCICLASS); the original connectivity of the 3S basin taking into account the two major waterfalls in the Sesan and Sre Pok rivers was estimated at 80.9%. With existing dams, the connectivity has been reduced to 23.5%, and with all planned dams, it is reduced further to 10.9%. The resulting re-distribution of fish species occurring throughout the 3S basins is explored, by focusing on migratory guilds and threatened and endemic fish species. With all dams built, it is predicted that the total numbers of species in HydroBasins above the dams will be reduced by 40–50%. The Threatened Species Index is estimated to fall from over 30 near the confluence of the three rivers to less than 10 above the lowest dams on the 3S rivers. The analysis demonstrates how widely available global and regional datasets can be used to assess the impacts of dams on fish biodiversity in this region. [ABSTRACT FROM AUTHOR]

The Yellow River Estuary and its adjacent waters serve as crucial spawning, foraging, and nursery areas for marine organisms, possessing abundant biological resources. Monitoring fish communities provides a baseline for implementing the sustainable utilization of marine resources. In this study, data were collected from 15 spring surface and bottom sites and 17 summer surface sites using eDNA and trawl surveys. The results showed that 37, 40, and 35 fish species were detected using eDNA in the spring (surface and bottom) and summer (surface), respectively, with 38 fish species caught during summer trawling. The dominant species mainly belonged to Engraulidae of Clupeiformes in the spring and Gobiidae of Perciformes in the summer, characterized by smaller-sized, short-lived, and pelagic fish species. The summer surface communities exhibited higher diversity than the spring surface and bottom communities. NMDS analysis revealed a degree of seasonal differences in fish communities and that there may be a lack of vertical stratification in the spring communities. The pH and DO were identified as the key environmental factors affecting the fish community. Additionally, the combination of eDNA and trawl surveys was regarded as a superior survey method. Our study provides valuable information for understanding seasonal fish communities in the Yellow River Estuary and its adjacent waters, contributing to fishery resource management and conservation in the region. [ABSTRACT FROM AUTHOR]

The concept of "state fishes of India" highlights the importance and significance of the prioritized fish species distributed across various states within the country. This review article systematically documents the current status of state fishes from various perspectives, identifies the prevailing knowledge gaps, and also highlights the issues and strategic plans essential for the conservation and sustainable utilization of these valuable genetic resources. A total of 8357 publications were checked for the consolidated information on state fish species, and the appropriate items were selected under eight categories: biology, physiology and nutrition, aquaculture, habitat and environmental parameters, genetics and biotechnology, harvest and postharvest, fish health management, and others. The synthesized information was used to present the current status of research and development on state fish species. The knowledge gaps that are to be addressed are also depicted under the perspectives of fisheries management and conservation aquaculture. Based on the findings, strategic plans for the targeted conservation programmes are proposed and discussed under various in situ and ex situ conservation measures. Further, the departmental processes involved in the declaration, the importance of stakeholder involvement, namely, local communities and policymakers, in fostering effective conservation measures, and planning for utilization of these valuable fish genetic resources are also indicated. [ABSTRACT FROM AUTHOR]

The present study delved into the world of hidden diversity by examining specimens identified as Leporinus piau from the river basins of the northern Brazilian states of Maranhão and Piauí. Using genetic analyses that combined data from three mitochondrial markers and one nuclear marker, the study identified two well‐supported groups, reinforcing the findings of previous publications. The first group, found in samples from the Itapecuru, Mearim, Turiaçu, and Pericumã basins, in Maranhão, appears to represent a relatively ancient diversification and the possibility of concealed cryptic diversity. The second group, comprising specimens from the Parnaíba (Piauí) and Mearim (Maranhão) basins, appears to have resulted from a more recent process of diversification and has a close relationship with Leporinus friderici from the type locality. Our findings not only confirm the existence of a complex scenario of cryptic diversity in the genus Leporinus from the study basins but also underscore the taxonomic inconsistencies within this group of fish. This study offers a comprehensive analysis of the species diversity of the Maranhão and Piauí basins, which are critical regions for the conservation of Amazonian fish, providing valuable insights for the sustainable management and conservation of these fish. [ABSTRACT FROM AUTHOR]