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AbstractThe Mekong River basin is a biodiversity hotspot and supports the largest inland capture fishery globally. The fish and fisheries, especially migratory species that underpin the capture fisheries, are, however, under threat from multiple pressures, not least hydropower development, expansion of irrigated agriculture and aggregate mining. In this paper the Global Swimways concept was used to understand migratory patterns in different Mekong fish species and provide insights for management and conservation of migratory species in the basin. Information was collated from existing databases, FishBase, and literature searches to determine the significance of migration routes of the river system. A total of 1393 fish species was recorded. About 21% of these are truly migratory species, mostly potamodromous and amphidromous species, and contribute ≈70% of catch. Distribution of fish in the Mekong River exhibits a well-defined zonation pattern, with species diversity highest in the lower floodplains and delta reaches. Three main migration zones occur in the Lower Mekong Basin (LMB) but with considerable migration of some species between zones. Some species adopt multiple migration strategies as opposed to simple longitudinal or lateral migrations, with sub-populations occurring in different reaches of the LMB exhibiting different migratory strategies. Approximately 11% of native fish species are threatened; among migratory species 35% are threatened. There are multiple challenges to maintaining swimways in the Mekong, including improved understanding of migratory pathways, managing intensification of environmental pressures and managing heavy fishing pressure. Measures to conserve and protect the migratory fish species in the Mekong are suggested. [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]

Accelerating rate of human impact and environmental change severely affects marine biodiversity and increases the urgency to implement the Convention on Biological Diversity (CBD) 30×30 plan for conserving 30% of sea areas by 2030. However, area‐based conservation targets are complex to identify in a 3‐dimensional (3D) ocean where deep‐sea features such as seamounts have been seldom studied mostly due to challenging methodologies to implement at great depths. Yet, the use of emerging technologies, such as environmental DNA combined with modern modeling frameworks, could help address the problem. We collected environmental DNA, echosounder acoustic, and video data at 15 seamounts and deep island slopes across the Coral Sea. We modeled 7 fish community metrics and the abundances of 45 individual species and molecular operational taxonomic units (MOTUs) in benthic and pelagic waters (down to 600‐m deep) with boosted regression trees and generalized joint attribute models to describe biodiversity on seamounts and deep slopes and identify 3D protection solutions for achieving the CBD area target in New Caledonia (1.4 million km2). We prioritized the identified conservation units in a 3D space, based on various biodiversity targets, to meet the goal of protecting at least 30% of the spatial domain, with a focus on areas with high biodiversity. The relationship between biodiversity protection targets and the spatial area protected by the solution was linear. The scenario protecting 30% of each biodiversity metric preserved almost 30% of the considered spatial domain and accounted for the 3D distribution of biodiversity. Our study paves the way for the use of combined data collection methodologies to improve biodiversity estimates in 3D structured marine environments for the selection of conservation areas and for the use of biodiversity targets to achieve area‐based international targets. [ABSTRACT FROM AUTHOR]

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 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]

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]

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]

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]

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]

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]

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]

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]

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]

The AFS Idaho Chapter held its 61st Annual Meeting jointly with the AFS Washington-British Columbia Chapter. The meeting took place in Spokane, Washington and had a total of 420 registrants, including students, retirees, and professionals. The meeting focused on the theme of "Returning Home: Anadromous Fisheries in the Pacific Northwest" and featured plenary speakers discussing topics such as the cultural significance of Pacific salmon, rebuilding runs in the Snake River basin, and the adaptive abilities of salmonids in response to climate change. The meeting also included workshops, symposia, business meetings, and awards ceremonies. The next meetings for both chapters are scheduled for 2025. [Extracted from the article]

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]

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]

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]

Objective: Successful conservation and management of fishes require an understanding of their age and growth. However, methods for estimating the age and growth of long‐lived fish species are difficult to validate. The Kootenai River basin has a decades‐long mark–recapture program for endangered White Sturgeon Acipenser transmontanus. The mark–recapture history information for White Sturgeon allowed for the evaluation of fin rays for age and growth analysis. Methods: Age was estimated from pectoral fin rays of known‐age White Sturgeon (n = 162) to evaluate ageing accuracy and precision. Lengths were back‐calculated using four models and measurements obtained from two fin ray transects (i.e., lateral and posterior). Result: Between‐reader agreement for White Sturgeon ages was 58.7%. Consensus age agreement with known ages was poor (30.7%) and decreased with age. Among the four back‐calculation models, the Fraser–Lee model provided the lowest root mean square error and percent error. Estimates of mean back‐calculated lengths at age derived from the Fraser–Lee model were similar between the two measurement transects. Back‐calculated lengths at age were similar to known lengths at age. Conclusion: Ageing of White Sturgeon using fin rays was unreliable, and accuracy decreased with fish age. Back‐calculated lengths at age were accurate using measurements from fin rays of known‐age fish. Length estimates from the two measurement transects were similar when using the Fraser–Lee method, suggesting that they may be used interchangeably. Impact statementValidation of age and growth information for long‐lived species is difficult. Although age estimates regularly underestimated true age of White Sturgeon, particularly for fish older than age 10, growth estimates were similar to known lengths at previous ages. As such, fin rays are likely suitable for evaluating age and growth of White Sturgeon, but results from such analyses should be interpreted with appropriate caution. [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]

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 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]

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 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]

Displaying antigens on yeast surface as an oral vaccine has been widely explored, while its potential as an immersion vaccine has not been evaluated. Here, an immersion vaccine was prepared by displaying ORF25 of Cyprinid herpesvirus 2 (CyHV‐2) on the surface of Saccharomyces cerevisiae. Carassius auratus gibelio was immersion immunized by 2 × 107 CFU/mL yeast for 2 h, and reinforce the immunity using the same method 14 days after the first immunization. The results showed that ORF25 specific antibody in immunized crucian carp serum was detected at a high level, and the mRNA expression level of IgM, IgT, IL‐1β, and IFN‐1 in vaccinated head‐kidney and spleen tissues were higher than the control group, indicating that innate and adaptive immunity were induced. Moreover, the immersion vaccination provided effective protection for fish against CyHV‐2, leading to a relative percent survival of 50.2%. Meanwhile, immersion vaccination restrained virus replication and histological damage in CyHV‐2 infected crucian carp. Our data suggested that immersion immunization of S. cerevisiae‐displayed ORF25 could be served as a candidate vaccine to prevent CyHV‐2 infection. [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]

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]

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]

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]

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]

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]

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]

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]

Stream restorations are increasingly critical for managing and recovering freshwater biodiversity in human-dominated landscapes. However, few studies have quantified how rehabilitative actions promulgate through aquatic communities over decades. Here, a long-term dataset is analyzed for fish assemblage change, incorporating data pre- and post-restoration periods, and testing the extent to which native assemblage stability has increased over time. In the late 1950s, a large capacity dam was installed on Putah Creek (Solano County, CA, USA), which altered the natural flow regime, channel structure, geomorphic processes, and overall ecological function. Notably, downstream flows were reduced (especially during summer months) resulting in an aquatic assemblage dominated by warm-water nonnative species, while endemic native species subsisted at low levels as subordinates. A court-mediated Accord was ratified in 2000, providing a more natural flow regime, specifically for native and anadromous fishes in the stream. The richness of nonnative species decreased at every site following the Accord, while the richness of native species increased or stayed constant. At the three most upstream sites, native species richness increased over time and ultimately exceeded nonnative richness. Native assemblage recovery was strongest upriver, closer to flow releases and habitat restoration activities, and decreased longitudinally downstream. Rank-abundance curves through time revealed that, while species evenness was low throughout the study, dominance shifted from nonnative to native species in the upstream sites coincident with rehabilitation efforts. Mean rank shifts decreased following flow rehabilitation; thus the assemblage became increasingly stable over time following flow rehabilitation. Putah Creek's rehabilitation may represent a model for others interested in improving endemic freshwater communities in degraded ecosystems.

The management and conservation of fisheries and aquatic resources are inherently applied activities. Therefore, when knowledge generated from research and monitoring, or knowledge that is held by practitioners and other actors (e.g., Indigenous elders, fishers), fails to inform those applied decisions, the persistent gap between knowledge and action is reinforced (i.e., the knowledge–action gap). In the healthcare realm, there has been immense growth in implementation science over the past decade or so with a goal of understanding and bridging the gap between knowledge and action and delivering on evidence‐based decision making. Yet, within fisheries and aquatic sciences, the concept of implementation science has not received the same level of attention. We posit, therefore, that there is an urgent need to embrace implementation science to enhance fisheries and aquatic management and conservation. In this paper, we seek to describe what implementation science is and what it has to offer to the fisheries and aquatic science and management communities. For our context, we define implementation science as the scientific study of processes and approaches to promote the systematic uptake of research and monitoring findings and other evidence‐based practices into routine practice and decision making to improve the effectiveness of fisheries management and aquatic conservation. We explore various frameworks for implementation science and consider them in the context of fisheries and aquatic science. Although there are barriers and challenges to putting implementation science into practice (e.g., lack of capacity for such work, lack of time to engage in reflection, lack of funding), there is also much in the way of opportunity and several examples of where such efforts are already underway. We conclude by highlighting the research needs related to implementation science in the fisheries and aquatic science realm that span methodological approaches, albeit a common theme is the need to involve practitioners (and other relevant actors) in the research. By introducing the concept and discipline of implementation science to the fisheries and aquatic science community, our hope is that we will inspire individuals and organizations to learn more about how implementation science can help deliver on the promise of evidence‐based management and decision making and narrow the gap between research and practice. [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 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 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]

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]

Seabirds interact with fishing vessels to consume fishing discards and baits, sometimes resulting in incidental capture (bycatch) and the death of the bird, which has clear conservation implications. To understand seabird–fishery interactions at large spatiotemporal scales, researchers are increasing their use of simultaneous seabird and fishing vessel tracking. However, vessel tracking data can contain gaps due to technical problems, illicit manipulation, or lack of adoption of tracking monitoring systems. These gaps might lead to underestimating the fishing effort and bycatch rates and jeopardize the effectiveness of marine conservation. We deployed bird‐borne radar detector tags capable of recording radar signals from vessels. We placed tags on 88 shearwaters (Calonectris diomedea, Calonectris borealis, and Calonectris edwardsii) that forage in the northwestern Mediterranean Sea and the Canary Current Large Marine Ecosystem. We modeled vessel radar detections registered by the tags in relation to gridded automatic identification system (AIS) vessel tracking data to examine the spatiotemporal dynamics of seabird–vessel interactions and identify unreported fishing activity areas. Our models showed a moderate fit (area under the curve >0.7) to vessel tracking data, indicating a strong association of shearwaters to fishing vessels in major fishing grounds. Although in high‐marine‐traffic regions, radar detections were also driven by nonfishing vessels. The tags registered the presence of potential unregulated and unreported fishing vessels in West African waters, where merchant shipping is unusual but fishing activity is intense. Overall, bird‐borne radar detectors showed areas and periods when the association of seabirds with legal and illegal fishing vessels was high. Bird‐borne radar detectors could improve the focus of conservation efforts. [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]

Transdisciplinary approaches combining technical perspectives with qualitative insights from the social sciences and non-academic stakeholders have emerged as a promising way to address the complexity of current socioenvironmental crises. However, transdisciplinary incorporation of diverse interests, knowledge, and worldviews requires acknowledging and addressing inherent inequities. Our case study combines two complementary transdisciplinary studies, the first conducted by a biologist/ecologist being trained in inter- and transdisciplinary methods at the time of the study, applying a quick participatory diagnosis in a fishing community, while the second is conducted by a social scientist studying the research group itself. Our results allow an exploration of the challenges and possibilities of navigating from transdisciplinary ideals to practical implementation. Our findings highlight the importance of nurturing relationships built on care, reciprocity, and openness to address the power imbalances inherent in university-community participatory practices. We suggest that the community's autonomy and agency can be preserved while actively engaging its members in the transdisciplinary process, alleviating power differences and fostering a collaborative and equitable transdisciplinary framework. Overall, we emphasize the significance of integrating participatory methods, critical reflexivity, and attention to power dynamics in realizing the potential of transdisciplinary approaches for addressing complex conservation challenges and fostering meaningful community engagement. [ABSTRACT FROM AUTHOR]