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The 2010 Gulf of Mexico Deepwater Horizon was the largest oil spill in human history that occurred during a 12-week period in a region less than 100 km from the coast of Louisiana; however, after more than a decade of post-spill research, few definitives can be said to be known about the long-term impacts on the development and distribution of fishes in and around the region of the disaster. Here, we examine endemic Gulf of Mexico fish species that may have been most impacted by noting their past distributions in the region of the spill and examining data of known collecting events and observations over the last twenty years (ten years prior to the spill, ten years post-spill). Five years post-spill, it was reported that 48 of the Gulf's endemic fish species had not been collected and, with expanded methods, we now report that 29 (of the 78 endemic species) have not been reported in collections since 2010 (five of these are only known from observations post-spill). Although the good news that some previously 'missing' species have been found may be cause to celebrate, the lack of information for many species remains a cause for concern given focused sampling efforts post-spill. [ABSTRACT FROM AUTHOR]

Ethiopia has considerable freshwater potential. Currently, the recognized fish diversity in the country's freshwater ecosystem is more than 200. Despite the presence of such high fish diversity with considerable economic returns, ichthyofaunal studies on Ethiopian rivers are scarce. Thus, this study aimed to identify and compare ichthyofaunal diversity and distribution in floodplain rivers of the Abbay and Tekeze Basins, Ethiopia. Fish were collected using gillnets, cast nets, hooks, electrofishing, and mosquito nets and identified to the species level. Gillnets had stretched mesh sizes of 4–14 cm with a panel length of 25–75 m and a width of 1.5–2 m per mesh size. They were set in the afternoon (5:00 p.m.) and lifted the following morning (7:30 a.m.). Immediately after capture, fish were preliminary identified in the field and tagged with proper information (e.g., sampling locality and date of collection). Similar fishing efforts were applied at all sampling sites for two dry and two wet months over a period of two years (2018-2019). In the present study, both alpha and beta diversity indices were also examined. Identification keys and an annotated checklist of species were generated for easy naming of the entire fish species in the basins. In the ichthyological collection, 43 fish species with 11 new records from the Ayima, Gelegu, and Shinfa Rivers were identified. The first two rivers in the Abbay Basin were the richest in species and number of individuals. Gelegu River had the highest abundance as well. Generally, this study was conducted in areas where no fish biodiversity studies have been undertaken, and the results obtained from this study could be important for fish biodiversity conservation. [ABSTRACT FROM AUTHOR]

Length-weight relationships are presented for twelve fish species collected at 22 sampling points in the Heishui River, a priority tributary for fish conservation in the mainstream of the Baihetan Reservoir area, China. A combination of gill nets was used for sampling over a period between November 2018 and May 2021. The gill nets consisted of 12 nets per point with dimensions of 20 × 2 m (length and width), mesh size ranging from 20 to 80 mm, and soaking depth ranging from 40 to 160 cm. In addition, fixed gill nets were employed, with 10 nets per point having dimensions of 10 to 30 m in length and 1.5 to 2.5 m in width. The mesh size of these fixed gill nets was 10, 15, or 20 mm. This study presents the length-weight relationships of twelve species for the first time in the Heishui River Basin, including the new maximum body length of Pseudorasbora parva (Temminck and Schlegel, 1846). The slope (b) values for the assessed species ranged from 2.5 to 3.5. All the estimated relationships are highly significant (P < 0.05) with a high coefficient of determination R 2 ranging from 0.9574 to 0.9997. It is expected that the results obtained from this study will contribute to filling the knowledge gap in this area and also assist fisheries scientists in future assessment studies. [ABSTRACT FROM AUTHOR]

Hydropower operations significantly alter the natural hydrological conditions of rivers, exerting adverse effects on riverine ecosystems. Accurate identification of fish habitats under hydropower operation and maintaining suitable ecological flow are crucial for riverine ecological conservation and water resource management. Coreius guichenoti was selected as the target species and the Yibin reach of the downstream Jinsha River was selected as the studied river reach. Subsequently, Weighted Usable Area (WUA) and Habitat Connectivity Index (HCI) were employed to comparatively analyze the habitat quantity and quality before and after the construction and operation of the Xiangjiaba hydropower station, namely the natural period (1991–2005), construction period (2006–2014), and operation period (2015–2020). Finally, correlations between WUA, HCI, and flow were established to determine the optimal ecological flow corresponding to optimal fish habitats. The results indicate that the average WUA and HCI during the construction period are similar to the natural period. In comparison to the natural period, the average WUA decreases by 9.2%, and the average HCI decreases by 0.05 during the operation period. It is determined that the habitat conditions are optimal when the flow is between 3000 and 5000 m3/s. After further refining the flow scenarios, the suitable ecological flow is determined to be 3500 m3/s. This study can provide a scientific basis for the water resources management in the Jinsha River and contribute to the field of riverine ecological conservation and restoration. [ABSTRACT FROM AUTHOR]

China harbors a high species diversity of freshwater fishes not shared with any of its neighboring nations. Freshwater fish diversity in the country has been under severe threat from human activities over the past decades, thus conservation freshwater fishes and ecosystems is urgently needed. To accumulate baseline data for guiding protection actions, the third red list assessment of Chinese freshwater fishes was carried out. Among Chinese freshwater fishes assessed, there are 355 at‐risk species (22.3% of the total), including 69 ranked as Critically Endangered, 97 as Endangered, and 189 as Vulnerable. Two species are classified as Extinct and one as Regionally Extinct. China's threat level seems to be lower than the known average level found in the IUCN's global assessment of freshwater fishes, but this is an artifact of a high rate of species classified as Data Deficient. Conservation of freshwater fishes is presently facing a grim situation in China. Imperilment of Chinese freshwater fishes is primarily attributed to habitat loss and degradation arising from human perturbations, particularly river damming. Despite the adoption of protected areas setting up, captive breeding and release, and a fishing moratorium, conservation efforts for freshwater fishes are compromised by disproportional attention in China's biodiversity conservation, baseline data deficiency, insufficiently designed protection networks, and inefficient or inadequate implementation of conservation strategies. To achieve the objectives of Chinese freshwater fish conservation, it is proposed to conduct a national‐scale survey of fish diversity and reassess their at‐risk status, develop systematic conservation planning of freshwater fish diversity and ecosystems, prioritize strategies for protected areas development, perform genetic‐based captive breeding for releasing in concert with other protection actions, and implement flexible fishing moratorium strategies in different water bodies. [ABSTRACT FROM AUTHOR]

Conservation practices from the perspective of functional diversity (FD) and conservation prioritization need to account for the impacts of exotic species in freshwater ecosystems. This work first simulated the influence of exotic species on the values of FD in a schemed mechanistic model, and then a practical case study of conservation prioritization was performed in the Min River, the largest river in southeastern China, to discuss whether including exotic species alters prioritization. The mechanistic model revealed that exotic species significantly altered the expected FD if the number of exotic species occupied 2% of the community. Joint species distribution modelling indicated that the highest FD occurred in the west, northwest and north upstreams of the Min River. Values of FD in 64.69% of the basin decreased after the exotic species were removed from calculation. Conservation prioritization with the Zonation software proved that if first the habitats of exotic species were removed during prioritization, 62.75% of the highest prioritized areas were shifted, average species representation of the endemic species was improved and mean conservation efficiency was increased by 7.53%. Existence of exotic species will significantly alter the metrics of biodiversity and the solution for conservation prioritization, and negatively weighting exotic species in the scope of conservation prioritization is suggested to better protect endemic species. This work advocates a thorough estimate of the impacts of exotic species on FD and conservation prioritization, providing complementary evidence for conservation biology and valuable implications for local freshwater fish conservation. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are experiencing accelerating global biodiversity loss. Thus, knowing where these unique ecosystems' species richness reaches a peak can facilitate their conservation planning. By hosting more than 290 freshwater fishes, Iran is a major freshwater fish hotspot in the Middle East. Considering the accelerating rate of biodiversity loss, there is an urgent need to identify species‐rich areas and understand the mechanisms driving biodiversity distribution. In this study, we gathered distribution records of all endemic freshwater fishes of Iran (85 species) to develop their richness map and determine the most critical drivers of their richness patterns from an ecoregion approach. We performed a generalized linear model (GLM) with quasi‐Poisson distribution to identify contemporary and historical determinants of endemic freshwater fish richness. We also quantified endemic fish similarity among the 15 freshwater ecoregions of Iran. Results showed that endemic freshwater fish richness is highest in the Zagros Mountains while a moderate level of richness was observed between Zagros and Alborz Mountains. High, moderate, and low richness of endemic freshwater fish match with Upper Tigris & Euphrates, Namak, and Kavir & Lut Deserts ecoregions respectively. Kura – South Caspian Drainages and Caspian Highlands were the most similar ecoregions and Orumiyeh was the most unique ecoregion according to endemic fish presence. Precipitation and precipitation change velocity since the Last Glacial Maximum were the most important predictors of endemic freshwater fish richness. Areas identified to have the highest species richness have high priority for the conservation of freshwater fish in Iran, therefore, should be considered in future protected areas development. [ABSTRACT FROM AUTHOR]

Garra cambodgiensis (stonelapping minnow) has experienced significant population declines, prompting intensive research and management, although its distribution in river systems such as the Mekong remains obscure. Effective conservation and management necessitate accurate monitoring and survey data on the distribution of freshwater species. Traditional surveying techniques for fish may be challenging and generate insufficient data on species distribution. This study developed an eDNA‐based method for detecting G. cambodgiensis to address this void. Twenty‐one locations were surveyed. Water samples were collected in triplicate from the river's surface at each site and processed within 48 h in a dedicated laboratory. Primers and probes for G. cambodgiensis were meticulously designed and species‐specificity tested to ensure accurate detection without interference from co‐occurring species in the same geographic range. Each water sample was analysed by qPCR using six technical replicates. The results of qPCR were reported as positive with quantifiable eDNA concentration (copies/mL), below the limit of quantification, or non‐detectable. G. cambodgiensis eDNA was detected in water samples collected from 10 out of 21 sampling sites, with concentrations ranging from 8.5 to 2990.0 copies/mL. Importantly, G. cambodgiensis eDNA was consistently detected in all three replicate water samples at each site where the qPCR experiment yielded positive results. The findings of this study demonstrate the feasibility and effectiveness of incorporating eDNA‐based monitoring or surveys for G. cambodgiensis in the ecologically diverse Mekong River. Monitoring based on eDNA can aid in targeting and informing conservation and management of G. cambodgiensis in its natural habitat. Comprehensive and robust information on species distribution can be obtained via an eDNA‐based survey, which could contribute to more efficient and informed decision‐making processes in fisheries management and conservation efforts. [ABSTRACT FROM AUTHOR]

The large number of cryptic species and extensive intraspecific phenotypic plasticity among freshwater fishes pose a challenge to the correct assessment of diversity within these taxa, which is crucial for their conservation. Recently, three different genetic lineages have been identified within the Italian endemic South European roach Sarmarutilus rubilio , a threatened species with a broad ecological niche. Using geometric morphometrics, we tested the existence of morphological differences associated with genetic common ancestry (i.e. between lineages) and/or environmental parameters. We observed streamlined body shapes in sites scarcely altered by human intervention and with fast water flow; on the contrary, we observed deeper body shapes in canals and in one reservoir with slow/still water flow. Our results suggest that morphological diversity in the South European roach is mainly a result of phenotypic plasticity in response to different environmental drivers (i.e. lotic vs. lentic hydrodynamic patterns) rather than different genetic backgrounds. [ABSTRACT FROM AUTHOR]

Ayer Hitam Utara State Park Forest (AHUSPF) is an invaluable sanctuary in Johor, the last remaining intact peat swamp forest reserve that hosts many species unique to this distinctive habitat. Some rapid surveys conducted from 2019 to 2022 recorded 40 species of freshwater fish within AHUSPF. Notably, 11 are stenotopic to acid blackwater, and 12 are stenotopic to acid water, most belonging to the family Osphronemidae and Danionidae. The International Union for Conservation of Nature Red List has designated two species, Encheloclarias curtisoma and Betta persephone, as Endangered, while Betta omega is classified as Critically Endangered. The checklist presented herein was first produced from an inventory study in AHUSPF. The preservation of peat swamp forests in the area is under imminent threat due to the alarming rate of land conversion, forest fires, and the recent potential threat from the red-claw crayfish invasion in the aquatic environment. Hence, continuous monitoring is vital for documenting and updating the conservation status of the fish species. These endeavours will facilitate the development of practical conservation approaches to ensure the long-term sustainability of AHUSPF and its associated species. [ABSTRACT FROM AUTHOR]

Simple Summary: We constructed a high-quality genome assembly of Eupleurogrammus muticus at the chromosomal level using PacBio SMRT, Illumina Nova-Seq, and Hi-C technologies. By combining genomic annotation, comparative genomic analyses, and species attribute information, we identified many candidate genes related to the whip-like tail, innate immunity, and DNA repair of E. muticus, and determined the evolutionary relationship and divergence time between E. muticus and related species. These findings provide important genomic resources for exploring the genetic mechanisms underlying the unique characteristics of E. muticus and fishery resource conservation. Smallhead hairtail (Eupleurogrammus muticus) is an important marine economic fish distributed along the northern Indian Ocean and the northwest Pacific coast; however, little is known about the mechanism of its genetic evolution. This study generated the first genome assembly of E. muticus at the chromosomal level using a combination of PacBio SMRT, Illumina Nova-Seq, and Hi-C technologies. The final assembled genome size was 709.27 Mb, with a contig N50 of 25.07 Mb, GC content of 40.81%, heterozygosity rate of 1.18%, and repetitive sequence rate of 35.43%. E. muticus genome contained 21,949 protein-coding genes (97.92% of the genes were functionally annotated) and 24 chromosomes. There were 143 expansion gene families, 708 contraction gene families, and 4888 positively selected genes in the genome. Based on the comparative genomic analyses, we screened several candidate genes and pathways related to whip-like tail formation, innate immunity, and DNA repair in E. muticus. These findings preliminarily reveal some molecular evolutionary mechanisms of E. muticus at the genomic level and provide important reference genomic data for the genetic studies of other trichiurids. [ABSTRACT FROM AUTHOR]

Small‐scale fisheries are vital to millions of rural people, but surprisingly little is known about the environmental and socio‐economic factors that guide rural peoples' decisions to adopt a fishery‐oriented livelihood. We analyzed data from a large‐scale household survey of 3929 households in 235 rural communities in the Peruvian Amazon to develop multi‐scalar quantitative models to explain engagement in fishing and the relationship between fishing livelihoods and poverty. Households harvested an average of 1000 kg of fish and sold 450 kg over the 12 months preceding interviews. The mean total annual income was 3119 USD per household and fishing contributed 27% to total income. Access to extensive floodplain habitat, geographical isolation, and an available workforce were important drivers of fishing activity, while poor market connectivity and limited financial capital restricted households from increasing the scale of market‐oriented fishing. Wealthier households generally harvested more fish, whereas reliance on fisheries was greatest among poorer households who harvested less fish. Fisheries management and conservation initiatives in developing regions must consider the distinct drivers of fishing specialization across the full wealth spectrum with particular attention to "high reliance‐high harvest" households. [ABSTRACT FROM AUTHOR]

The mucus layers of fish serve as the main interface between the organism and the environment. They play an important biological and ecological role. The current study focuses on Nile tilapia epidermal mucus reared under different commercial feeds (coded A and B) and environments (biofloc technology and earthen pond systems). Crude protein levels in feed A and B were 30% and 28%, respectively. Water parameters in all culturing systems were suitable for tilapia throughout the study period. The antimicrobial potency of tilapia (n = 5 from each) epidermal mucus was tested in vitro against human and fish pathogenic strains viz. Staphylococcus epidermidis, Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Francisella noatunensis, and Aeromonas hydrophila. To determine the antimicrobial activity, zones of inhibition (ZOI) were measured in millimetres and compared with two antibiotics (chloramphenicol and ciprofloxacin). SDS‐PAGE analysis was performed on skin mucus samples of tilapia to determine protein quantity and size (molecular weight). Results of tilapia skin mucus (crude and aqueous) revealed a strong antibacterial effect against all the selected pathogenic strains. However, variation has been observed in the mucus potency and ZOI values between the biofloc and pond tilapia mucus. The crude mucus of tilapia fed on feed A and cultured in the pond exhibited strong antibacterial effects and high ZOI values compared to the mucus of biofloc tilapia, aqueous mucus extracts and positive control chloramphenicol (antibiotic). The SDS‐PAGE results showed that the high molecular weight proteins were found in the collected epidermal mucus of BFT‐B (240 kDa) and EP‐B (230 kDa). Several peptides in fish skin mucus may play a crucial role in the protection of fish against disease‐causing pathogens. Thus, it can be utilized in the human and veterinary sectors as an 'antimicrobial' for treating various bacterial infections. [ABSTRACT FROM AUTHOR]

There is very little information on Andean condors scavenging on fish. Here we report five events of condors feeding on fish carrion in the Bolivian Chaco Serrano in three consecutive years. In 2019, 2020, and 2021, condors were observed feeding on discarded fish from local fishermen, 3 km west of Villa Montes, in the 'El Angosto' section of the Pilcomayo River. Fishing, mainly for sábalo (Prochilodus lineatus), is the most important economic activity in that part of the Pilcomayo basin and its discards explain fish carrion availability there, while driving scavengers to feed on this resource. We believe that fish carrion abundance, the intensity of intra‐ and interspecific competition for access to carrion, and overall carrion availability hierarchically influence the fact that condors feed on fish, something we will investigate later based on the observations reported here. From a conservation perspective, the main consequence of scavengers feeding on fish from the Pilcomayo is that they could be getting heavy metal poisoning. Heavy metal poisoning is a serious threat with widely known negative effects for wildlife. Our observations should serve to promote comprehensive bio‐monitoring of the Pilcomayo basin, using approaches such as One Health, and emphasizing the importance of coexistence between humans and the rest of biodiversity, with the Andean Condor as the flagship species. [ABSTRACT FROM AUTHOR]

Objective: Natural dispersal or unauthorized introductions of nonnative predatory sport fish can undermine native species conservation and other fisheries management objectives. The use of reproductively sterile triploid fish may provide a lower risk stocking option (i.e., genetic and reproductive containment) for diversifying angling opportunities while possibly reducing angler motivation to illegally transplant fish. Management interest in triploid Walleye Sander vitreus is growing, and these fish are currently stocked by several fisheries agencies. However, little is known about the poststocking growth, body condition, and survival of triploid Walleye—information that is important for calibrating expectations and guiding policy regarding their use. Methods: We compared the age‐specific size, body condition, and survival of subadult (i.e., ages 0–3) triploid Walleye to those of normal diploid conspecifics in two eastern Colorado reservoirs. Paired stockings of triploid and diploid Walleye occurred over 3 years. Both fry and fingerlings were stocked each year. Result: Triploids were generally smaller in length (6.6% smaller on average) and weight (20.6% smaller) compared to diploids across all age‐classes. Despite being smaller, triploids had similar body condition relative to diploids. On average, the survival of triploids from spring stocking to their first fall was 6.3× lower than that of diploids, but no differences in survival were observed beyond this early life stage. This pattern was consistent across cohorts and reservoirs. Conclusion: The present work provides a foundation for future studies that are designed to clarify patterns of survival from spring to the first fall by accounting for size at stocking and natural‐origin fish and studies that are planned to assess the poststocking performance of triploid Walleye independent of diploids. Impact statementBalancing recreational fisheries management with native species conservation efforts can be challenging, especially in cases where anglers highly value nonnative predators. The practice of stocking sterile fish is an emerging management approach aimed at addressing concerns about introducing or maintaining existing populations of predatory fish outside of their native range. While artificially induced triploidy is among the most common methods for producing sterile fish, little is known about how triploid fish grow and survive in the wild, information that is crucial for decision making regarding their use. In this study, we provide some of the first information regarding the size, body condition, and survival of triploid Walleye relative to normal, diploid Walleye in the wild. Our findings will aid managers in making decisions regarding the use of triploid Walleyes in their programs. [ABSTRACT FROM AUTHOR]

Intraspecific functional variation is critical for adaptation to rapidly changing environments. For visual opsins, functional variation can be characterized in vitro and often reflects a species' ecological niche but is rarely considered in the context of intraspecific variation or the impact of recent environmental changes on species of cultural or commercial significance. Investigation of adaptation in postglacial lakes can provide key insight into how rapid environmental changes impact functional evolution. Here, we report evidence for molecular adaptation in vision in 2 lineages of Nearctic fishes that are deep lake specialists: ciscoes and deepwater sculpin. We found depth-related variation in the dim-light visual pigment rhodopsin that evolved convergently in these 2 lineages. In vitro characterization of spectral sensitivity of the convergent deepwater rhodopsin alleles revealed blue-shifts compared with other more widely distributed alleles. These blue-shifted rhodopsin alleles were only observed in deep clear postglacial lakes with underwater visual environments enriched in blue light. This provides evidence of remarkably rapid and convergent visual adaptation and intraspecific functional variation in rhodopsin. Intraspecific functional variation has important implications for conservation, and these fishes are of conservation concern and great cultural, commercial, and nutritional importance to Indigenous communities. We collaborated with the Saugeen Ojibway Nation to develop and test a metabarcoding approach that we show is efficient and accurate in recovering the ecological distribution of functionally relevant variation in rhodopsin. Our approach bridges experimental analyses of protein function and genetics-based tools used in large-scale surveys to better understand the ecological extent of adaptive functional variation. [ABSTRACT FROM AUTHOR]

The high demand for carp as consumed fish nor decorative fish, causes an increasing production. However, an obstacle occurs in production, due to the reproductive characteristics of Common Carp fish. Different times in sperm and egg production from male and female fish cause difficulties in breeding. Hence, it needed sperm preservation so the breeding could be done for the whole year. Natural extenders are the solution to preserve fish sperm without side effects. The purpose of this study was to determine the effect of different types of extenders and different doses on the percentage of sperm motility and viability of carp (Cyprinus carpio) after storage This research was conducted at the Faculty of Fisheries and Marine Sciences, Universitas Brawijaya and the Freshwater Cultivation Installation (IBAT Punten), Batu, East Java. The method in this study was Complete Random Design (CRD) with 6 treatments, K (100ml lactate ringer); A (1ml cider + 99ml lactate ringer); B (1ml coconut + 99ml lactate ringer); C (1ml date juice + 99ml lactate ringer); D (1ml honey + 99ml lactate ringer); E (1ml sugar cane + 99ml lactate ringer). The results showed that the highest motility was obtained in the treatment using date extract extender with a motility percentage rate of 77.66%; the highest viability was obtained in the honey extract with 80.71%; and the highest fertility rate was obtained in the honey extract treatment with 72.67 %. [ABSTRACT FROM AUTHOR]

Cave-obligate aquatic organisms are difficult to monitor for conservation due to cryptic diversity, unknown subterranean hydrological connectivity, and accessibility to habitats. Conservation management practices have benefitted from evolutionary data; however, the evolutionary and biogeographic histories of most cave-obligate organisms are unknown. The modes and patterns leading to most cave-obligate organism distributions are also uncertain. The Southern Cavefish (Typhlichthys subterraneus, Amblyopsidae) is the largest ranging cavefish in the world but represents a species complex of which the distribution and relatedness within remains unclear. To explore modes of cave-adaptive evolution, we performed population genomic analyses on a dataset of single nucleotide polymorphisms harvested from ultraconserved elements. We found five to eight strongly delineated genetic clusters. Little to no genetic exchange occurred between clusters, indicating high genetic distinctiveness and low connectivity, a concerning result for the fitness and conservation of these fishes. Genetic clusters did not correspond to caves nor to other geographic boundaries examined. Unfortunately, one of the geographic units most easily communicated for conservation– caves– do not match the biological units of interest. Our results support multiple independent colonization events from a widespread surface ancestor with a small degree of cave connectivity among, but not between, clusters. We suggest whole cave system conservation. [ABSTRACT FROM AUTHOR]

Objective: Shark depredation, the full or partial consumption of a hooked fish by a shark before it is landed, is an increasing source of human–wildlife conflict in recreational fisheries. Reports of shark depredation in the catch‐and‐release Tarpon (also known as Atlantic Tarpon) Megalops atlanticus fishery in the Florida Keys are increasing, specifically in Bahia Honda, a recreational fishing hot spot and a putative Tarpon prespawning aggregation site. Methods: Using visual surveys of fishing in Bahia Honda, we quantified depredation rates and drivers of depredation. With acoustic telemetry, we simultaneously tracked 51 Tarpon and 14 Great Hammerheads (also known as Great Hammerhead Sharks) Sphyrna mokarran, the most common shark to depredate Tarpon, to quantify residency and spatial overlap in Bahia Honda. Result: During the visual survey, 394 Tarpon were hooked. The combined observed shark depredation and immediate postrelease predation rate was 15.3% for Tarpon that were fought longer than 5 min. Survival analysis and decision trees showed that depredation risk was highest in the first 5–12 min of the fight and on the outgoing current. During the spawning season, Great Hammerheads shifted their space use in Bahia Honda to overlap with Tarpon core use areas. Great Hammerheads restricted their space use on the outgoing current when compared to the incoming current, which could drive increased shark–angler interactions. Conclusion: Bahia Honda has clear ecological importance for both Tarpon and Great Hammerheads as a prespawning aggregation and feeding ground. The observed depredation mortality and postrelease predation mortality raise conservation concerns for the fishery. Efforts to educate anglers to improve best practices, including reducing fight times and ending a fight prematurely when sharks are present, will be essential to increase Tarpon survival and reduce shark–angler conflict. Impact statementShark depredation in recreational fisheries is an increasing source of human–wildlife conflict in the United States. This study quantified shark depredation in the Tarpon fishery and characterized the spatial ecology of Great Hammerheads and Tarpon in Bahia Honda in the Florida Keys. [ABSTRACT FROM AUTHOR]

An increasing focus on aquaculture using introduced strains or species poses a serious threat to native wild species in sub‐Saharan Africa, yet almost no policies have been enacted or regulations put in place to address this environmental challenge. Aquaculture in these regions has traditionally been conducted on a relatively small scale but is currently expanding rapidly and is projected to continue increasing in the coming decades, with increasing use of genetically improved strains. This expansion is occurring in a region known for its high biodiversity, creating challenges for increasing fish production without damaging wild fish populations. However, few studies have yet assessed the impacts of changes in aquaculture practice on the genetic composition and diversity of wild populations. The use of non‐native improved strains for aquaculture could cause competition, gene introgression when there is interbreeding with native populations or species, displacement of species and possible extinction of the native wild populations.After providing historical context on African aquaculture, this review describes the current methods of fish breeding and genetic improvement programmes for the main species of cultured fishes, focusing on the potential conservation impacts of the use of introduced (and selectively bred) farmed species. Existing aquaculture policies, legislation and regulations regarding the import and farming of fish are then compared across the main fish‐producing countries. We recommend a regional policy framework considering fish introduction, risk analysis and risk management, human resources development and genetic monitoring that could be drafted into the existing policies to strengthen conservation efforts.We conclude by making recommendations for refining existing regulations and for future research aimed at minimizing the impacts of aquaculture on wild fish populations in sub‐Saharan Africa. Aquaculture in this region needs implementation of responsible guidelines to avoid genetic impacts on native populations of high conservation value. [ABSTRACT FROM AUTHOR]

Aquatic wildlife health assessment is critically important for aquatic wildlife conservation. However, the health assessment of aquatic wildlife (especially aquatic wild animals) is difficult and often accompanied by invasive survey activities and delayed observability. As there is growing evidence that aquatic environmental microbiota could impact the health status of aquatic animals by influencing their symbiotic microbiota, we propose a non-invasive method to monitor the health status of wild aquatic animals using the environmental microbiota health index (microHI). However, it is unknown whether this method is effective for different ecotype groups of aquatic wild animals. To answer this question, we took a case study in the middle Yangtze River and studied the water environmental microbiota and fish gut microbiota at the fish community level, population level, and ecotype level. The results showed that the gut microHI of the healthy group was higher than that of the unhealthy group at the community and population levels, and the overall gut microHI was positively correlated with the water environmental microHI, whereas the baseline gut microHI was species-specific. Integrating these variations in four ecotype groups (filterfeeding, scraper-feeding, omnivorous, and carnivorous), only the gut microHI of the carnivorous group positively correlated with water environmental microHI. Alcaligenaceae, Enterobacteriaceae, and Achromobacter were the most abundant groups with health-negative-impacting phenotypes, had high positive correlations between gut sample group and environment sample group, and had significantly higher abundance in unhealthy groups than in healthy groups of carnivorous, filter-feeding, and scraper-feeding ecotypes. Therefore, using water environmental microHI to indicate the health status of wild fish is effective at the community level, is effective just for carnivorous fish at the ecotype level. In the middle Yangtze River, Alcaligenaceae, Enterobacteriaceae (family level), and Achromobacter (genus level) were the key water environmental microbial groups that potentially impacted wild fish health status. Of course, more data and research that test the current hypothesis and conclusion are encouraged. [ABSTRACT FROM AUTHOR]

Development of Florida's marine Fisheries-Independent Monitoring (FIM) program began in 1985, and it initiated long-term monitoring in Tampa Bay in 1989 with the purpose of providing timely fishery-independent data and analyses to fishery managers for the conservation and protection of the species that support Florida's fisheries. Over time, the program expanded sampling in other Florida estuaries. Data from this monitoring program are integral to the assessment and management of numerous state and federally managed fishes, so long-term consistency is of paramount importance, but sampling design modifications have been necessary over time. This review presents three case studies in which the estuarine component of the FIM program was changed to address emerging data needs in management of Florida's fishery resources, while maintaining standardization and consistency with long-term surveys statewide. In the first case study, survey changes increased the amount of data on juvenile common snook, Centropomus undecimalis, on the Gulf of Mexico and Atlantic coasts and improved indices of abundance, survival estimates, and age-length keys for state management purposes. In the second case study, the FIM program improved estimates of abundance of juvenile reef fishes by initiating a complementary survey that expanded FIM sampling to new regions of the Florida Gulf coast and targeted a unique habitat (polyhaline seagrass beds along estuarine shoal habitats) not previously sampled in the standard longterm survey. In the third case study, the FIM program addressed a data limitation for regional management of spotted seatrout, Cynoscion nebulosus, by initiating seasonal sampling in western Florida. In each case study, the standard long-term survey design was modified to include sampling of new and unique areas and habitats, providing valuable data on estuarine fish assemblages that support analyses at the broader, ecosystem level. Survey amendments were designed to maintain standardization and consistency, all with limited additional funding. The success of these survey modifications was the result of several key factors: mission-focused programmatic goals, geographically dispersed laboratories, standardized protocols, ongoing critical analysis of the data, grant award success, and high-level data management. Although each case study originated with a survey expansion, all were followed by survey reductions or streamlining, so expansion and reduction scenarios are presented in this review. Regardless of these modifications, the mission of the FIM program remains the same: to provide timely data and analysis for the use of fishery managers, including state and federal partners. [ABSTRACT FROM AUTHOR]

Recent technological advancements have facilitated the extensive collection of movement data from large-scale fishing vessels, yet a significant data gap remains for small-scale fisheries. This gap hinders the development of consistent exploitation patterns and meeting the information needs for marine spatial planning in fisheries management. This challenge is specifically addressed in the Campania region of Italy, where several Marine Protected Areas support biodiversity conservation and fisheries management. The authors have created a spatially-explicit dataset that encompasses both large-scale (vessels exceeding 12 meters in length) and small-scale (below 12 meters) fishing efforts. This dataset (available at https://doi.org/10.6084/m9.figshare.23592006) is derived from vessel tracking data and participatory mapping. It offers insights into potential conflicts between different fishing segments and their interactions with priority species and habitats. The data can assist researchers and coastal management stakeholders in formulating policies that reduce resource competition and promote ecosystem-based fisheries management. Furthermore, the provided mapping approach is adaptable for other regions and decision-making frameworks, as we are committed to sharing the tools and techniques we employed. [ABSTRACT FROM AUTHOR]

Walleye is an important sportfish across eastern North America, is commercially fished in the Laurentian Great Lakes region, and has been introduced outside its native range. Thirty-eight Walleye populations within six watersheds across the Eastern Highlands and other portions of the native range were screened at eight microsatellite DNA loci to better understand evolutionary history and to inform fishery management and conservation efforts. Population genetic variation showed divergent assemblages of populations, respectively, living in the Mobile Bay, Mississippi River, Eastern Highlands (Tennessee, New, and Ohio Rivers), and Great Lakes drainages today. All estimates of effective numbers of breeding individuals were under 25, and all populations within all watersheds had ~15–20% inter-individual relatedness, likely attributable to the effects of both natural demographic processes and stocking. The extent of Eastern Highlands Walleye includes both the Ohio and Tennessee River basins. [ABSTRACT FROM AUTHOR]

The European Fish Index EFI+ is the only fish-based multimetric index for the assessment of the ecological status of running waters that is validated and thus applicable across most countries of the European Union. Metrics of the index rely on several attributes of the species present in the fish assemblage, irrespective of their native/alien status. The abundance of alien fish, together with other anthropogenic impacts, is one of the most important threats to the conservation of native fish and ecosystem health and is also an indicator of degraded stream conditions. Therefore, to improve the performance of the EFI+ in regions with high incidence of alien species, the EFI+ was adapted to include alien fish pressure as a new metric that reflects the number of alien species as well as the proportional abundance of alien individuals. The application of the adapted index (A-EFI+) is illustrated with data from several Iberian Mediterranean basins and showed similar or stronger correlations than the original EFI+ with anthropogenic pressure (land-use variables and alterations in hydrology and river morphology) and with other regional fish indices. EFI+ has been invaluable to intercalibrate fish indices across Europe, and A-EFI+ is similar but explicitly includes alien pressure, thus helping to provide a more comprehensive assessment of ecosystem health and to communicate it to society. [ABSTRACT FROM AUTHOR]

Isaza Gymnogobius isaza, a small freshwater goby endemic to Lake Biwa, Japan, is categorized as "Endangered" in the International Union for Conservation of Nature Red List of Threatened Species; nevertheless, it remains subject to fishing without any specific management strategies. The sex ratio, and gonadosomatic and hepatosomatic indices of Isaza caught by commercial bottom trawl and set net while migrating to and from an offshore pelagic area and nearshore spawning area were investigated in Lake Biwa from winter to early summer. Male spawning migrations preceded those of females. In addition, mortality during spawning was male-biased. Both findings suggested a possible impact of the commercial set net fishery on Isaza reproduction. Future conservation and fisheries management of the species need to be considered. [ABSTRACT FROM AUTHOR]

Fish is an important resource in Malawi as a source of food for the majority as it provides affordable source of dietary animal protein as well as income. A number of fish species in the Malawi water bodies have their population dwindling. One of the species under serious threat of extinction is the Opsaridium microlepis - a potamodromous fish species that migrate to the rivers during its spawning period and its management seems a nightmare. A number of studies reveal contrasting results on genetic makeup and morphological aspect of this fish species. With changes in the ecosystems of the rivers connecting Lake Malawi, coupled with absence of strong management measures in the major rivers adjoining the lake, problems have arisen in the conservation of potamodromous fish species. This necessitated the present study to investigate if the morphological features of stocks of O. microlepis are the same or not and if they have changed to adapt to changes in the ecosystems. One hundred and eleven O. microlepis fish samples were collected from Linthipe River (48), Bua River (59) and North Rumphi River (4) monthly from March to August 2020 using trawled and static gillnets. Twenty-four morphometric characteristics were measured to determine if any morphological differences existed among the fish samples from the three rivers. Principal component analysis (PCA) was used to compare morphology of the fish. Results of the study showed no significant morphological differences among stocks from the three rivers, implying that O. microlepis in these rivers belong to same stock morphologically. The study reveals that the species do not differ morphologically even though they migrate to different rivers for breeding. The study further notes that numerous activities taking place along the tributary rivers (as observed during the study) such as modification of fishing gears as well as fishing methods and the deterioration of the spawning grounds due to siltation from soil erosion caused by deforestation and agriculture, are putting the potamodromous fish species such as O. microlepis under serious threat. The study recommends that the populations of O. microlepis from the rivers can be managed equally since they are morphologically similar. Adopting uniform catchment management and sustainable exploitation of O. microlepis (such as regulations on mesh sizes and fishing methods, closing the rivers from fishing activities during spawning period, river bank and catchment management and restoration) with the aim of conserving the stocks from further overexploitation in these rivers is recommended so that the communities and the people at large continue to utilize the resource sustainably and at the same time, sustaining their livelihood. [ABSTRACT FROM AUTHOR]

Studies relating to fish trophic ecology provide important insights regarding their life history. However, there is a lack of information linking fish diet composition with riparian cover in small streams. To investigate whether diet composition varied between streams with pristine and logged forests, I compared the food items consumed by four characid species: Bryconops melanurus, Moenkhausia collettii, Moenkhausia dichroura, and Moenkhausia oligolepis. I sampled 18 first‐order streams in the eastern Amazon: six with pristine forest, six with conventional logging, and six with selective logging. All fish species were classified as omnivorous, with diverse food categories recorded in their diets: mainly terrestrial insects for Moenkhausia species and aquatic insect nymphs for B. melanurus. However, the relative importance of each category varied only in streams with conventional logged forests. In these streams, all fish species consumed mainly autochthonous items, especially aquatic insect nymphs. In addition, terrestrial insects and seeds were absent in these streams with reduced riparian cover. In summary, this study highlighted that fish diet in conventional logged forests strongly differed from areas with pristine and selective logged forests. This finding states that managed forests may support a diverse diet for fish community, similar to that found in pristine forests. Therefore, management and conservation strategies of riparian vegetation in Amazonian streams are important to maintain habitat and food quality, which may be associated with a diverse diet for fish species. [ABSTRACT FROM AUTHOR]

The European Union Water Framework Directive (WFD) is a comprehensive initiative guiding river basin water management, addressing pressures such as pollution from diffuse and point sources, and hydromorphological alterations. However, pressures that can deteriorate the ecological quality of water bodies through biotic changes (i.e., by the introduction of non-indigenous species) are not rigorously addressed by the WFD. This study explores associations between conventional ecological quality indices based on physicochemical and biotic quality elements (fish and macroinvertebrates) against the presence and densities of non-indigenous freshwater fish species (NIFS) in lotic ecosystems of Greece, aiming to unravel the potential usage of NIFS in future ecological assessments. The dataset comprises 277 samplings at 115 sites, covering physicochemical and biotic (fish and macroinvertebrate) quality indices, and anthropogenic pressure variables. Based on our findings, the occurrence and densities of four NIFS (Lepomis gibbosus, Pseudorasbora parva, Gambusia holbrooki, and Carassius gibelio) were highly associated with the ecological quality assessments of the applied indices. Higher occurrences and densities of these NIFS were related to samplings of lower ecological quality. In addition, NIFS exhibited a positive association with anthropogenic pressures, likely due to their adaptability to less optimal environmental conditions or higher tolerance to pollution and other stressors. Our findings underscore the need for a paradigm shift in ecological quality assessments, emphasizing the use of NIFS either as a potential indicator of ecosystem health or as a pressure that deteriorates ecological quality. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems are the most threatened on Earth, with many species facing extinction. The Clanwilliam sandfish (Labeo seeberi) is South Africa's most threatened migratory freshwater fish and is endemic to the Olifants–Doring River system in the Cape Fold Ecoregion. Non‐native fish predation and river desiccation have caused a recruitment bottleneck, severely compromising juvenile survival and resulting in a declining population of aging sandfish. The Saving Sandfish Project launched an emergency head‐start intervention in 2020 to reduce extinction risk. We (1) rescued juvenile sandfish from drying pools in a key spawning tributary (the Biedouw River); (2) relocated them to 6 off‐stream reservoirs; and (3) released reservoir‐reared sandfish back into their natal river once large enough to evade non‐native fish predation. Here, we estimate survival in the reservoir environment, evaluate return rates relative to wild run size, and assess the probability of return based on conditions at release. Between 2020 and 2022, we stocked 33,391 juvenile sandfish into the 6 reservoirs. After 1 year, the estimated survival rate at one reservoir was 0.679 (range based on 95% CI: 0.385–0.973). Release and return results are presented only for the first (2020) rescue cohort. In 2021, we released 1277 sandfish from 2 reservoirs into the Biedouw River, comprising 16.6% of the 2020 rescue cohort. Mean size at release was 169 mm (SE 0.6) total length. Of those released, 994 were PIT‐tagged. A total of 77 PIT‐tagged sandfish were recorded during the 2022 spawning migration—a return rate of 7.7% of tagged releases in the first year of returns. Size of fish and distance from the Doring River at release were significant predictors of return probability, with larger fish released further from the Doring experiencing a higher probability of return. This program serves as a model for the conservation of freshwater fish where there is an imminent and high risk of extinction. [ABSTRACT FROM AUTHOR]

The Río San Pedro and Río La Pasión lie within the Usumacinta River Basin, a globally significant center of freshwater fish diversity. Both rivers are listed among Central America's top 50 regions for conserving freshwater biodiversity. This study presents an updated checklist of 70 fish species, of which six are non-native to the Usumacinta River Basin. From these species, 69 are reported from the Río La Pasión and 56 reported from the Río San Pedro, representing higher species richness than previously reported. The checklist derives from a systematic survey of fishes conducted in 2019 and records available in public databases and published literature. Seventy-eight percent of the species were reported in both rivers, and Cichlidae and Poeciliidae had the most species. Secondary species represent 59% of the species reported, followed by peripheral species with 22% of the species. The species with highest fidelity in Río La Pasión were the armored catfish Pterygopichthys spp. and the livebearer Gambusia sexradiata; and the cichlids Thorichthys meeki and Oscura heterospila had highest fidelity in the Río San Pedro. Thorichthys helleri was widely distributed in both rivers. According to the IUCN Red List of Threatened Species, there are four species classified as Vulnerable in Río La Pasión. However, 62% of the species are of Least Concern, 25% of the species are Data Deficient, and 6% are listed as Not Evaluated. More research is needed to document the status of the fish fauna, and improved habitat protection is required to conserve stocks. [ABSTRACT FROM AUTHOR]

In recent years there has been a growing focus on filling critical knowledge gaps on the challenge of abandoned, lost, and discarded fishing gear (ALDFG) in the global ocean. While not the biggest contributor to the world's marine debris problem, ALDFG has been shown to be a particularly deadly form of marine litter due to its ability to entangle, entrap, and ensnare marine wildlife, damage coastal habitats, and result in negative economic impacts to the fishing sector. In the Eastern Caribbean region, fisheries play a crucial role in ensuring livelihood and food security for vulnerable coastal communities. Therefore effective management interventions that are geared towards eliminating anthropogenic threats to the marine environment, including ALDFG are considered of paramount importance. This article aims to gain insight into challenges associated with the governance of ALDFG within the small-scale fisheries of the Eastern Caribbean with a view to outlining opportunities for improvement. A qualitative approach was utilized and interviews were conducted with fisheries and conservation experts from both national and regional-level institutions. The participants revealed that ALDFG was of significant concern for their country or the region and each advocated for the establishment of improved management infrastructure. Identified barriers that could impede this critical goal include limited human and financial capacity, lack of knowledge and understanding of ALDFG generally, lack of trust, and policy incoherence across sectors and between regional and national agencies. To overcome barriers, a multi-faceted approach is required, including regulatory and institutional improvements. [ABSTRACT FROM AUTHOR]

This document provides a summary of several recent decisions by the European courts in environmental matters. The first case discussed concerns the European Investment Bank (EIB) and its refusal to provide an internal review of its decision to grant a loan for the construction of a biomass power plant in Spain. The Court of Justice (CJEU) ruled that the EIB must provide for an internal review of its decision. The second case involves the diesel scandal, specifically the imposition of double sanctions on Volkswagen in Italy and Germany. The CJEU found that the Italian sanction constituted a criminal sanction and applied the principle of "ne bis in idem," which prohibits double jeopardy. The third case focuses on the enforcement of the Habitats Directive and the failure of Member States to designate special areas of conservation and implement appropriate conservation measures. The CJEU ruled that the European Commission must prove that conservation measures are incomplete, insufficient, or inappropriate for each Natura 2000 site. The final case addresses the quality of drinking water in Italy and the failure of certain municipalities to comply with EU requirements. The CJEU found that Italy had not complied with its obligations under Directive 98/83 and had not improved the situation as quickly as possible. Overall, these cases highlight the complexities and challenges in enforcing environmental laws and protecting the environment. [Extracted from the article]

The Assamese snake-head fish, Channa stewartii (Playfair, 1867) is endemic to the Brahmaputra River Basin (upper, middle, and lower) in India and Bangladesh, as well as the Ganges River basin extending from southern Nepal south-eastward. This study aimed to examine the taxonomic status and the length-weight relationship and condition factor of C. stewartii populations from a newly found community in Assam, Morigaon district, India. Taxonomic assessment involves morphological examination and comparison with existing literature to confirm the species identity. The morphological observation clearly indicated that C. stewartii specimens were distinguished by their blue fins with black patches, red fin edges, and reddish-pink pectoral fins. The female fishes have slightly duller, yellowish colours than the males, although they still have brighter colours than the males. Phylogenetic analyses also showed that our recent collection was clustered with C. stewartii from Assam, India. Measurements of C. stewartii length-weight relationship exhibited that both male (b = 3.389) and female (b = 3.396) showed a positive allometric growth. Additionally, the condition factor (K) for both sexes exceeded 1, indicating the well-being and health of the fish in their habitat. The findings contribute to the understanding of the ecological characteristics and population dynamics of C. stewartii in Morigaon district, providing valuable information's for fisheries management and conservation efforts in the region. [ABSTRACT FROM AUTHOR]

Arctic char (Salvelinus alpinus) and Dolly Varden (S. malma) are two closely related species in the genus Salvelinus. Both species show substantial intra-specific variation in ecology, morphology, and post-glacial history across their distributional ranges, which has presented substantial challenges for conservation and management and has led to the coining of the term, 'the charr problem'. Arctic char and Dolly Varden have been studied extensively by scientists since the 1700s, not only because these fishes play important ecological roles within ecosystems, but also because they are culturally, economically, and recreationally valuable. While several detailed reviews have been published on Arctic char over the past 40 years, Dolly Varden remain understudied. In addition, advances in the fields of genetics, ecology, and morphometrics have improved our understanding of the behavior, feeding, habitat requirements, post-glacial histories and intraspecific diversity of each of these two species. Herein, we present an updated review that focuses on placing findings from more recently published (through 2022) phylogenetic, ecological and morphometric studies within the foundational context of earlier papers and reviews (since 1943). We also review anticipated effects of climate change on both species. Across their ranges, Arctic char and Dolly Varden can display a variety of life history types, with many populations exhibiting anadromy and/or potadromy; due to their use of distinct habitats at specific life stages, migratory chars are vulnerable to climate-induced changes to habitat quantity and quality. In addition to reviewing the existing literature, we highlight knowledge gaps and research priorities that, when addressed, will enable more informed conservation and management initiatives for these highly valued fishes. [ABSTRACT FROM AUTHOR]

With increasing emphasis on ecological environment conservation, the conservation of fish habitat and the regional carbon balance need to be incorporated into the operation process of reservoirs. In this research, formulas for calculating ecological and environmental objectives in reservoir operation were obtained by fitting the curve of discharge and fish habitat area and comprehensively analysing the factors affecting reservoir carbon emissions. Additionally, we used the multi-objective optimization algorithm NSGA-II-DE to study the competitive relationship between the economic, ecological, and environmental benefits of the Longtoushi Reservoir and proposed a relatively optimized operation scheme using the multi-objective decision-making method VIKOR. The results of this scheme showed that the power generation, weighted usable area (WUA) and carbon emissions of Longtoushi Reservoir during the study period were 5.74 × 108 kW h, 9.61 × 104 m2 and 51.32 t, respectively. Compared with the relative optimal operation scheme, the power generated by the maximum power generation scheme increased by 2.66%, the WUA decreased by 1.68%, and carbon emissions increased by 9.86%; the power generation of the maximum WUA scheme increased by 0.16%, the WUA decreased by 0.08%, and carbon emissions increased by 0.72%; and the power generation of the minimum carbon emission scheme increased by 3.14%, the WUA decreased by 1.62%, and the carbon emissions increased by 9.14%. In general, competition between power generation, WUA and carbon emissions is inevitable, and reducing the water level in reservoirs can effectively increase ecological and environmental benefits. [ABSTRACT FROM AUTHOR]

The North American river otter Lontra canadensis was once widespread in North America but became extinct in the State of Indiana owing to habitat losses and unregulated trapping. However, following reintroduction, the population has expanded markedly since 1995, representing a notable conservation success story.The recent population growth has led to conflict with recreational angling groups who perceive otters as competitors. To investigate the extent of this competition, a DNA‐based study was conducted to determine whether material from the stomachs of trapper‐harvested otters could be used to identify fish prey species they had eaten.Representative specimens from 33 wild fish species were used as positive controls for DNA assays of otter prey. Mitochondrial DNA barcoding sequences generated from each fish species were used to develop a piscine barcoding assay to identify otter prey species.Fourteen otter carcasses were dissected, and multiple independent DNA extractions and mitochondrial sequencing reactions were performed on the prey bolus from each stomach. The sequences were analysed bioinformatically for taxonomic assignment to prey species.DNA evidence of nearly two dozen fish species, including species of recreational (e.g. bass) or conservation interest (darters) was found in the stomach material.This approach could help to determine the presence of prey species in otter diets, including those fish of conservation concern. That, in turn, would help to determine the best management options for conserving both otters and fish. [ABSTRACT FROM AUTHOR]

Habitat descriptions found in critical habitat designations and recovery plans are important for protecting endangered species. However, in order to protect critical habitat, it is necessary to update descriptions of habitat use when range shifts occur or new studies change the understanding of habitat use.This study examined the habitat use of a threatened desert fish to determine whether current habitat use matched the descriptions in recovery documents. Recovery documents describe humpback chub (Gila cypha) as being dependent on rocky, canyon‐bound habitats during all life stages, but recent surveys found humpback chub in open, silt‐laden habitats, suggesting this species may be able to occupy a wider range of habitats.Hoop net catch data from a long‐term monitoring project in the Colorado River were used to compare catches of two size classes: juvenile/subadult (<200 mm total length [TL]) and adult humpback chub (≥200 mm TL). Catch information was analysed on an individual net scale and on a geological segment scale using generalized linear mixed models.There was no difference in juvenile/subadult humpback chub catch between hoop nets set in rocky habitat compared with habitat with only fine sediment. Humpback chub catch for all life stages in a river segment characterized by silt banks exceeded or was not significantly different from catch in rocky segments.This case study demonstrates the importance of revisiting habitat descriptions, sampling in areas outside known or expected habitat and incorporating new data related to range expansion or habitat changes in recovery strategies to better describe and protect habitats that can support imperilled species. [ABSTRACT FROM AUTHOR]

The development of area‐based tools that combine fishing, aquaculture and repopulation practices is increasingly necessary and important to conserve ecosystems, promote sustainable use of marine resources and contribute to the well‐being of the people that rely on them.In the Gulf of California, Mexico, two small‐scale fishers' cooperatives were granted a Permit for Exploratory Aquaculture of bivalve species, and their members decided to set three zones within those concessions: (i) a zone for natural seed collection and repopulation, (ii) a no‐take zone and (iii) an area where fishing was allowed. This management arrangement, named by them as the Integral Management Zone (Zona de Manejo Integral), was conceived as an innovative alternative to the current policy tools available in the Mexican General Law for Sustainable Fisheries and Aquaculture.The natural collection of bivalve larvae in the artificial collectors was sufficient to allow the development of the repopulation project. Based on hydrodynamic models of larval dispersal, self‐recruitment was low, and the collection of seed depended on distant sources. The broader scale (regional) connectivity source–sink patterns should be considered in the design stages of the Integral Management Zones.The implementation of the Integral Management Zones can complement other conservation and fisheries management tools available in Mexican environmental and fisheries laws. The approach envisioned to implement this tool is participative, with a meaningful role of local fishers in the decisions concerning the use of these zones, with a supportive engagement of governmental and other stakeholders (e.g., academia and civil society organizations). [ABSTRACT FROM AUTHOR]

Sustainable fisheries management seeks to balance fisheries' conservation with fishers' economic well‐being. Marine protected areas are increasingly used as a component of management frameworks to improve the resilience of, or maintain, marine resources. However, any spatial management measures need to consider the seasonal distribution of key species at key life stages, such as the recruitment stage.Trichiurus japonicus (hairtail) is the highest yielding single fish species in China, but it is showing signs of miniaturization and early maturity, which are indicators of overfishing. Thus, it is a suitable model species for studies aiming to find a solution to the challenge of balancing fishing activities with resource protection.The potentially important seasonal nursery grounds of T. japonicus in the East China Sea were identified using a model combining data for the variability in abundance and the probability of occurrence of T. japonicus recruits. Based on fishery‐independent survey data, a Bayesian hierarchical species distribution model revealed that the locations and sizes of core nursery grounds of T. japonicus varied seasonally and that the main drivers were depth, sea bottom temperature and sea bottom salinity.The possible seasonal interactions between fishing effort and nursery grounds at different levels of importance were evaluated by analysing the spatial overlap between fishery hot spots and T. japonicus core nursery grounds. The results showed that the proportion of overlap was highest in spring and lowest in summer.These findings highlight the urgent need to develop fleet‐adapted management measures for different levels of overlap and suggest that the eastern and southern areas of the East China Sea hairtail national aquatic germplasm resources conservation zone (TCZ) should be included in conservation planning. [ABSTRACT FROM AUTHOR]

The Pacific seahorse (Hippocampus ingens) is a teleost fish native to the Pacific Ocean. In Mexico they are protected by national legislation; however, there are no studies regarding their commercial use or population status. From a conservation perspective they are a threatened fish and from a socio‐economic aspect they represent a source of income for many fishing communities. The integration of these two points of view requires, among other things, the recognition that fishers have knowledge and skills that can help implement conservation strategies and management plans for seahorses and their habitats.The objective was to document the knowledge of fishers from Sinaloa about the fishing status and current commercialization of wild populations of H. ingens. For this, semi‐structured interviews and participatory observation were carried out with 112 participants in the two main ports of the state of Sinaloa (Mazatlán and Topolobampo) from July to August 2021. The data obtained were coded and then, through content analysis, systematized results were obtained that allowed a qualitative and quantitative analysis.The species was found to be caught using six different fishing gears (catch per unit effort, CPUE = 0.07–1.24 seahorses per boat per day) and have an important financial value. Most fishers catch seahorses incidentally, but three of them mentioned targeting them directly. Fishers perceive a decrease in catches and in the size of the Pacific seahorse, as well as an increase in prices.The information analysed indicates that seahorse populations in Sinaloa are exploited and have economic value, despite current regulations. This study shows that the exploitation of seahorses in Sinaloa is unsustainable and requires the implemention of collaborative management strategies (e.g. stakeholder management, the establishment of marine protected areas, sustainable harvest practices, community‐based enforcement efforts, educational campaigns, research, and conservation partnerships) that fully take into account the knowledge and practice of local fishers of Sinaloa and Mexico. [ABSTRACT FROM AUTHOR]

The extensive nature of recreational angling makes it difficult to explore trends in global catches. However, trophy fishing world records may provide an insight into recreational fishing pressure on the largest species and size classes. Trophy fishing is promoted and recorded by the International Game Fish Association (IGFA), who manage an 80‐year database on the largest individuals of a species caught – called all‐tackle records (ATRs) – with information on the size and location of each record catch.We analyse these data to explore temporal trends in the size of record‐setting fishes, determine how past and present ATR catches are distributed globally, and examine trends in records for International Union for Conservation of Nature (IUCN) threatened species.The number of ATRs, and the number of species awarded an ATR, have increased significantly over the past 80 years. New records are for increasingly smaller maximum‐sized species of fish, with the average sized record shifting from 167.7 kg in the 1950s to 8.1 kg in the 2010s. ATRs for species listed as threatened (Vulnerable or higher) on the IUCN Red List have also declined by approximately 66% over the past two decades. Records were unevenly distributed around the world but have spread globally over time. Historically, ATRs were concentrated around the coastline of the USA but in recent decades more were reported in areas such as Japan and New Zealand.These data either reflect a shift away from mainly targeting large taxa to targeting a wider variety of smaller species, or that there are now limited larger specimens and so fewer ATRs are being set. Additionally, the scarcity of new records for threatened species appears to support IUCN assessments of their poor stock status. The spread of ATRs suggests a growing pressure on the largest size classes in regions with previously little trophy fishing pressure. We encourage the greater use of catch‐and‐release initiatives and mandatory data collection for all near records to better quantify trophy fishing pressure and ensure sustainable practices. [ABSTRACT FROM AUTHOR]

Fish entrainment from reservoirs to downstream rivers by various water release structures may result in serious consequences for reservoir ecosystems. This study proposed an integrated modeling approach for determining fish entrainment risk zones and suitable reservoir regulations. The modeling approach combines hydrodynamic and fish risk assessment modeling with using fuzzy rules set defined by expert knowledge in fish ecology. We applied this modeling approach in the Maling Reservoir in China, where fish entrainment in the reservoir has been observed in the turbine, spillway, and irrigation system. Percocypris pingi (Tchang, 1930) and Onychostoma simum (Sauvage & Dabry de Thiersant, 1874), representing the main and protected fish species, were selected as target fish species. Five reservoir operation schemes were investigated under normal and designed water levels. The modeling results suggest that the fish entrainment risk for protected fish species (Onychostoma simum) is higher than that for the main fish species (Percocypris pingi). The results indicate a ranking of the fish entrainment risk from high to low in the following scenarios: with all spillways in operations, with one spillway in operation, with intakes in operation, with an irrigation system in operation, and with intakes and the irrigation system in combined operations. In addition, under normal and designed water levels, dead fish entrainment zone areas and percentages were extremely low compared to the entire forebay of the reservoir. These results indicate that the operation of the Maling Reservoir does not affect the ecological status of fish. These findings are generally applicable to any fish species in reservoirs that balance reservoir operations and ecological protection of fish, and could assist reservoir managers in making informed decisions on how to mitigate and compensate for fish entrainment. [ABSTRACT FROM AUTHOR]

This research paper presents the first comprehensive assessment of ichthyofaunal diversity in Hisar district, conducted from October 2021 to March 2022. This study summarized fortnightly field data from the fish market and local fish farmer ponds. A total of 12 fish species belonging to 4 orders, 7 families and 12 genera were recorded in Hisar district. The order Cypriniformes was found to be the most dominant, with the Cyprinidae family being the most prevalent. Indian major carp, along with exotic carp, constituted a significant portion of the fish catch in Hisar district. The conservation status analysis revealed that 50% of the species were categorised as least concerned, 17% as near threatened, 17% as vulnerable, and 16% as nearly endangered. This study provides valuable insights into the ichthyofaunal diversity of Hisar district, contributing to our understanding of the local fish populations and their conservation needs. [ABSTRACT FROM AUTHOR]

The Short neck clam, Paphia malabarica, inhabits the ecologically diverse waters along the South Konkan coast of Maharashtra, serving as a vital resource for local communities. Concerns over the sustainability of clam populations necessitate a thorough investigation into the stock structure of P. malabarica to inform effective conservation and management strategies. This research employs geometric morphometrics to analyze shape variations in key morphological features of the clam, aiming to identify distinct morphotypes indicative of genetically differentiated stocks. The study area's diverse environmental conditions provide an intriguing context for understanding how local hydrodynamics, substrate composition and ecological interactions may influence phenotypic diversity within clam populations. Our findings aim to contribute valuable insights into the stock discrimination of P. malabarica, providing a foundation for informed conservation and fisheries management practices along the South Konkan coast of Maharashtra. [ABSTRACT FROM AUTHOR]

Anglers are a diverse population whose behaviours and perspectives are influenced by a myriad of factors including knowledge, expertise, management actions, and regulations. We examine similarities and differences in behaviours and perspectives amongst freshwater anglers of rainbow trout and steelhead (Oncorhynchus mykiss) in British Columbia, Canada, using an online survey. Findings from the survey suggest that subgroups or “types” of anglers are identifiable by differences in their behaviours and perspectives according to geographic area, gear type, fishery, and frequency of fishing activities. Our results indicate that angler types share many of the same motivations for engaging in fishing behaviours and similar concerns regarding threats to their preferred fishery; however, differences were evident across types of issues related to angler behaviour, as well as views on fisheries management. Overall, we argue that understanding fishery-scale angler heterogeneity can benefit fisheries management by highlighting areas of agreement and disagreement and encouraging tailored communications and relationship-building with important angler subgroups.

Objectives: Genus Labeo of family Cyprinidae comprising of important group of fish species are known for ornamental purpose, food, extracting oil, medicinal value and for potential viable aquaculture. The present study was conducted to assess the morphometric and molecular identification of freshwater fishes of genus Labeo including Catla catla, Labeo rohita, Labeo calbasu, Labeo gnius, Labeo bata from the three fish resources of River Indus, Punjab, Pakistan. Methods: Out of 75, thirty fish specimen were amplified and sequenced with 650 bp of mitochondrial COI gene for the evaluation of fish biodiversity, management and conservation by using different bioinformatics techniques. Results: Maximum and minimum genetic divergence between fishes of C. catla, L. calbasu, L. boga, L. gonius and L. rohita, were 0.052 to 0.105, respectively. Highest divergence was found between Labeo bata and Labeo rohita. Interspecific mean distance was found higher than intraspecific distance. In nucleotide base composition, AT contents was higher than GC contents indicated the clear pattern of anti-G bias. Transition rate was k1 = 8.84 for purines and transversional rate was k2 = 15.47 for pyrimidines with transition/transversion bias R = 5.62. Tajima D test and nucleotide diversity was measured D = 1.382883 and π = 0.049981 respectively. Positive value of D indicated a strong selective pressure and lack of population expansion. Thirty species were identified with e-value 0.0 and similar identity 99.85 %–100 % with maximum 600 bp length. Phylogenetic tree revealed two major clades with 95 % high bootstrap values identity showed closet relationship among these species. Conclusions: Current study supported the efficacy of the COI gene for the species identification in River Indus and develop the concept for establishing Pakistani fish gene bank which is still needed.