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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]

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]

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

Understanding the community structure and ecology of fish populations in rainforest streams is a prerequisite for any actions towards their exploitation, management or conservation. We examined the community structure and species diversity of nothobranchiids (African rivulines) in rainforest streams of Cameroon's southern plateau and part of the coastal plain, using data on 19 environmental variables for ecological indices and multivariate analyses. In total, 1 019 individual cyprinodontiforms assigned to 14 species (largely species of Aphyosemion) were collected, for a global sampling effort of 78.6%. The presence of nothobranchiids in the study area was associated with several local environmental factors common to all sampling sites, mainly canopy cover above the watercourse and physicochemical characteristics of the stream habitat. Distribution of the species was strongly spatially structured, driven by the site's elevation and the water temperature, and influenced primarily by the riparian vegetation, substrate type, water conductivity and flow velocity. However, fish species richness did not differ significantly between the five sectors sampled and by elevation. The nothobranchiid communities were highly diverse (Shannon's H′ = 2.28 ± 0.05; Pielou's J = 0.87) and the species evenly distributed. Seven species were exclusive to a single sector, others were prevalent in multiple sectors, and no species was common to all sectors. Affinities between species were relatively few, though there were exceptions, and most species tended to exclude each other. These findings highlight nothobranchiids as local fish assemblages having high biotic integrity and responsiveness to environmental degradation. In tropical Africa, these fishes often occupy fragile habitats influenced by anthropogenic activities. A better understanding of the unifying role of habitat in ecology will assist management efforts to promote biodiversity conservation. [ABSTRACT FROM AUTHOR]

Highlights: What are the main findings? The commercial small pelagic fishes (Decapterus maruadsi and Trachurus japonicus) in the Beibu Gulf were still miniaturizing. Fisheries management, characterized by reduced fishing efforts, cannot completely restore population structure in a short period. What are the suggestions for the future fisheries development in the Beibu Gulf? Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Simple Summary: Decapterus maruadsi and Trachurus japonicus, as the main commercial small pelagic fish in the coastal fisheries of China, have been facing the threat of population decline due to overfishing. In this work, we assessed the population status of two commercial small pelagic fish stocks in the Beibu Gulf (in the South China Sea) over the past 15 years (2006–2020). The analysis results show that the commercial small pelagic fishes in the Beibu Gulf were still miniaturizing, and fisheries management characterized by reduced fishing efforts cannot completely restore population structure in a short period. Continuing to maintain low fishing mortality and increasing the catchable length should be the key ways to achieve fishery resource conservation and recovery. Our findings will provide a key scientific basis for future improvements in offshore fisheries management. Long-term variations in population structure, growth, mortality, exploitation rate, and recruitment pattern of two major commercial small pelagic fishes (CSPFs) (Decapterus maruadsi and Trachurus japonicus) are reported based on bottom trawl survey data collected during 2006–2020 in the Beibu Gulf, South China Sea. All individuals collected during each sampling quarter over a period of 15 years were subjected to laboratory-based analysis. In this study, the stock of D. maruadsi and T. japonicus inhabiting the Beibu Gulf was assessed using length-based methods (bootstrapped electronic length frequency analysis (ELEFAN)) to complete stock assessment in different fishery management periods (the division of fisheries management periods was based on China's input and output in the South China Sea offshore fisheries over 15 years, specifically divided into period I (2006–2010), period II (2011–2015), and period III (2016–2020)). The results showed that the mean body length, dominant body size, and estimated asymptotic length of two CSPFs decreased, whereas their growth coefficient decreased, indicating miniaturization and slower growth, respectively. Estimated exploitation rates and catching body length for two CSPFs indicated that both stocks in the Beibu Gulf were overexploited in period I and moderately exploited after 2011. These stocks were taking a good turn in status in period III, with the exploitation rate much lower than the initial period and reversing the downward trend in catching body length. Furthermore, the variations in the spawning season of the two CSPF stocks and their barely satisfactory expected yield indicated the complexity of the current fishery management in the Beibu Gulf. These results suggest that management measures to reduce fishing pressure may have a positive influence on the biological characteristics of those CSPFs in the Beibu Gulf; however, the stock structure already affected by overfishing will be a huge challenge for the conservation and restoration of fisheries resources in the future. Given that the current stocks of D. maruadsi and T. japonicus in the Beibu Gulf still have low first-capture body length (Lc) and high fishing mortality (F) (compared to F0.1), we identify a need to refine population structure by controlling fishing efforts and increasing catchable size, and more consideration should be given to the local fishery resource status in fisheries management. [ABSTRACT FROM AUTHOR]

Accurate and precise estimates of survey abundance indices are essential inputs for stock assessment models and are important for the successful conservation and management of fisheries stocks. Since abundance indices can be standardized in various different ways, from conventional design-based approaches to model-based approaches, it is essential to compare the efficiency of those approaches and quantify the consequences for stock assessments. In this study, we focus on an important commercial stock of witch flounder (Glyptocephalus cynoglossus) in NAFO 3N+3O divisions. We first compare the survey indices standardized by design-based and model-based approaches, and find that a model-based estimator provides more precise estimates of survey indices than design-based approach for this stock. We then apply a widely used age-structured statistical catch-at-length (ACL) assessment model to the standardized catch-at-length survey indices from both approaches to estimate the age-based population dynamics for this stock. We conclude that the ACL model fit to model-based indices performed better than the same model fit to design-based indices. [ABSTRACT FROM AUTHOR]

The present research was conducted within the framework of a broader investigation with the objective of identifying freshwater parasites and bacteria on national territory, with the aim of gaining a deeper understanding of the relationships between parasites, hosts, and the environment, and to assess the potential detrimental effects of parasitic infestation on the conservation status of fish populations. Within this study, it was documented the first recordings of parasites Vorticella globularia and Epistylis sp. in the Romanian Petroleuciscus borysthenicus celensis fish species. A total of 42 specimens were collected from the Gurban River to study their infestation status, focusing on the skin, gills, and fins. From the samples analyzed, 16 specimens presented signs of infestation with five distinct parasite species (Ichthyophthirius multifiliis, Dactylogyrus vastator, Trichodina acuta, Vorticella globularia and Epistylis sp) and four bacterial strains (Aeromonas veronii, Shewanella putrefaciens, Aeromona hydrophila, and Citrobacter freundii). The results indicate that the skin is the organ most severely impacted by parasites and bacteria, followed by the gills. The fins, on the other hand, are the least susceptible to infection. Furthermore, the significant amount of parasitic infestation coupled with the high bacterial load of Aeromonas veronii indicates a plausible link between the two. [ABSTRACT FROM AUTHOR]

This study presents a comprehensive analysis of the length-weight relationship, condition factors, and age of Schizothorax eurystomus in the Shakhimardan River basin in Central Asia, along with a comparative perspective to other Schizothorax species in the region. The study found that S. eurystomus exhibits positive allometric growth, which is consistent with similar patterns observed in this species from the Syr Darya River basin. The two analyzed condition factors showed mean values within the normal range, indicating good feeding and environmental conditions. However, significant disparities between minimum and maximum values of these factors indicated varied growth conditions which may be influenced by anthropogenic factors. Age estimation using opercular bones showed variations in the total length among fish of the same age, and a clear age distribution pattern across different sites. Younger fish predominantly inhabited the shallower, warmer, and lower sections of the river, which is impacted by agricultural water diversion, while older specimens were found in areas with higher discharge and deeper pools. Overall, this research provides valuable insights into the life history traits of S. eurystomus, underlining the need for sustainable fishery management and conservation strategies in the Shakhimardan River basin. The findings also emphasize the importance of considering habitat quality and anthropogenic pressures regarding understanding both fish population dynamics and growth patterns. [ABSTRACT FROM AUTHOR]

Freshwater-limited fish populations are often tightly constrained by river drainage boundaries. As a case in point, the distribution of lineages within New Zealand's diverse Galaxias vulgaris complex is broadly structured by geographic barriers, reflecting tectonic processes. However, several drainages of the Central Otago region have been locally modified by past gold-mining activities, with artificial water races connecting formerly isolated headwaters of distinct river drainage systems. Here we synthesise published genetic data to highlight the role of anthropogenic catchment modification in redistributing fish diversity. These data show that several local phylogeographic anomalies for stream-resident Galaxias fishes are closely linked to anthropogenic connections across major drainage divides. While these anthropogenic translocations may parallel natural geologically-driven mixing events that occur on deeper time scales, they nevertheless have potential conservation implications given the increasing fragmentation of native fish populations. Our review also highlights the role of sub-catchment units in shaping the hierarchical structure of intraspecific biodiversity. [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]

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]

Israel's region forms a continental bridge; hence, the freshwater fish fauna in Israel consists of unique populations of species that originated from Africa, Asia, or Europe and are often endemic or at the edge of their distribution range. Worldwide, fish biodiversity suffers significantly from pressures and disturbances of freshwater habitats, especially in arid regions, such as in parts of Israel. Biodiversity conservation requires efficient tools for monitoring changes in populations. DNA barcoding, by complementing and enhancing species identification, provides such monitoring tools. In this study, over 200 specimens representing over 28 species were DNA barcoded and together with previously available records, a DNA barcoding database for freshwater fish of Israel was established. Of the 71 distinct barcodes generated, 37% were new, attesting to the uniqueness of fish populations in Israel. For most species, morphological and molecular species identifications agreed. However, discrepancies were found for five genera. Based on DNA barcoding, we propose Acanthobrama telavivensis as a junior synonym for Acanthobrama lissneri. In Garra spp., we propose splitting Garra nana into two species and assigning Garra rufa in the region to Garra jordanica, or possibly to two species. Israeli Pseudophoxinus kervillei is not the same species as in Syria and Lebanon. However, Pseudophoxinus syriacus might not be endangered since it is genetically very similar to Pseudophoxinus drusensis. In Israel, instead of five reported Oxynoemacheilus species, combining DNA barcoding with morphology suggests only three. Genetic and geographic separation suggested that Aphanius mento is likely a species complex. The study provides a thorough barcoding database, suggests significant species reconsiderations in the region, and highlights the Sea of Galilee and the Beit She'an valley streams as biodiversity "hotspots." This study will therefore promote further studying of the fish species in the region and their ecology, as well as the monitoring and conservation of freshwater fish biodiversity in Israel and the region. [ABSTRACT FROM AUTHOR]

Waterbodies are polluted by human activities or the increasing intensity of these activities, and this affects fish populations. The quality of the water fish inhabit directly impacts their growth and overall health. Length-weight relationships (LWRs) and relative condition factors (Kn) were estimated for three freshwater fish species from the Sutlej River of India from October 2020 to May 2022. A total of 232 fish specimens were caught with cast and gill nets in Gobindsagar Reservoir, Himachal Pradesh and Ropar Wetland, Punjab. Total length was strongly correlated with all the morphological characters (p < 0.001). The growth coefficients calculated (b) for Bangana dero, Cyprinus carpio, and Sperata seenghala were 2.858, 2.506, and 2.555, respectively, and indicated negative allometric growth. The correlation coefficients (r) indicated strong linear relationships between the weights and lengths of all three fish species. The outcomes of this study will help fisheries researchers, environmentalists, and scientists to develop future monitoring and conservation strategies for these fish species. [ABSTRACT FROM AUTHOR]

Fish migration is a complex and multifaceted phenomenon that plays a crucial role in shaping aquatic ecosystems and supporting the livelihoods of millions of people worldwide. By understanding the various types of fish migration and their ecological significance, scientists, policymakers, and resource managers can develop effective strategies for conserving migratory fish populations, restoring habitat connectivity, and promoting sustainable fisheries management. As human activities continue to exert pressure on aquatic ecosystems, efforts to protect and preserve migratory fish species are essential for maintaining the health and resilience of freshwater and marine environments. This paper delves into the various types of fish migration, highlighting their significance in ecosystem dynamics, fisheries management, and conservation efforts. [ABSTRACT FROM AUTHOR]

Central Valley Spring-run Chinook (CVSC) are listed as threatened under the California and federal Endangered Species Acts, but how ocean fisheries affect CVSC is not routinely monitored or managed, largely because of data limitations. Most tag data for CVSC are from a hatchery program that may not sufficiently represent natural-origin fish in ocean and inland fishery recovery data. However, a discontinued tagging program for Butte Creek Wild Spring-run Chinook (BCWSC) provides for estimation of fishery impacts and maturation schedules for a limited set of years, which we compared with estimates for hatchery-origin fish for common years, while extending the hatchery-origin estimates over a wider time-frame. Additional scale-age data from BCWSC allow inferences about more recent maturation rates, conditional on harvest-rate estimates borrowed from other stocks. Overall, CVSC appear to experience low age-3 ocean fishery impact rates, but age-4 impact rates can be comparable to ocean harvest rates estimated for Sacramento River Fall Chinook. Tagging data from the years available indicate that ocean fisheries may reduce spawning run sizes (all ages combined) by 40% to 60% during periods of high fishing effort. Effects of ocean fishing on spawner abundance are weaker in years of reduced fishing or for cohorts displaying earlier maturation. It appears that maturation rates of hatchery-origin CVSC may have increased (i.e., earlier maturation) over the full time-period examined, and there may be indications of increasing maturation rates for BCWSC as well. [ABSTRACT FROM AUTHOR]

Knowledge of the ecology, spatial distribution and conservation status of fish populations is achieved by fishery‐dependent techniques, and by more recently developed non‐invasive fishery‐independent techniques. Passive acoustic monitoring (PAM) is a fishery‐independent method that provides remote sensing of soniferous species, populations, communities and ecosystems by recording soundscapes and their components.A case study is presented to demonstrate how PAM can contribute to a dynamic understanding of fish distribution, ecological preferences and conservation status. This case study refers to the cusk‐eel Ophidion rochei (Ophidiiformes), a nocturnal, behaviourally cryptic, soniferous fish species, described as uncommon and rare in the scientific literature, and listed as Data Deficient in the IUCN Red List.A systematized literature review was carried out using Ophidion+rochei as the search term, and by grouping records into two main categories: (i) traditional techniques (including all fishery‐dependent techniques and underwater visual census); and (ii) PAM.This review highlights how PAM has provided new sightings of O. rochei at a rate three times higher than all other monitoring techniques combined. In contrast with the knowledge achieved to date by fishery‐dependent techniques, the reported acoustic mass phenomena indicate that this species can be very abundant. Ophidion rochei was found to inhabit a wide range of depths and ecosystems, at least throughout the Mediterranean basin.This paper supports the urgency and the importance of relying on the integration of different fishery‐independent techniques for multidisciplinary monitoring, in line with the Goal 14 requirements of the UN Decade of Ocean Science for Sustainable Development. [ABSTRACT FROM AUTHOR]

Establishing large networks of fully protected marine protected areas (MPAs) is challenging because of displacement costs for fisheries. The use of partially protected areas is often proposed as an alternative. However, how conservation and fisheries outcomes of MPA networks are mediated through time by the level of protection remains uncertain. Here we use a metapopulation model of a commercially exploited demersal coastal fish to assess conservation and fisheries outcomes of alternative management policies. We compare the temporal performances of nonspatial management, large MPAs, or networks of MPAs in an overfished case study. In addition, we assess how the magnitude of both outcomes is mediated by larval connectivity and level of protection. We distinguish the relative contribution to fisheries outcomes of unprotected areas in between MPAs, and unprotected areas further away, receiving less displaced fishing effort and potential biomass export. We show that spatial management outperforms nonspatial management, that conservation and fisheries outcomes increase with increasing levels of protection, that fisheries outcomes in areas in between MPAs are higher when connected through larval dispersal, and that increases in catch are preceded by a short‐term decrease. Our results call for an increase in protection levels to meet both ecological and fisheries management goals. [ABSTRACT FROM AUTHOR]

Dams are one of the main threats to Neotropical potamodromous fish, causing blockages of migratory routes and loss of breeding areas in an increasing number of drainage systems. In this scenario, current data argue that the maintenance of free-flowing tributaries along fragmented watersheds would be an important strategy to the migratory fish conservation, both in panmixia situations and in scenarios with different coexisting stocks, as already reported for Prochilodus lineatus. This study analyzed microsatellite loci and mitochondrial haplotypes in samples of P. lineatus obtained in different years along the Cinzas River basin, as well as in the Capivara Reservoir (largest Reservoir in the Paranapanema main channel, upper Paraná River) and in the Tibagi River, all connected by free stretches, aiming to investigate the contributions of the Cinzas River basin to the population dynamics of migratory fish in the Capivara reservoir region. Both markers detected high genetic diversity levels and indicated different genetic stocks of P. lineatus along the Cinzas River basin, suggesting some temporal genetic structuring, as well as the mixture of these stocks in the sample from the Capivara reservoir and from other points, corroborating the relationships among stocks in this reservoir and its tributaries. [ABSTRACT FROM AUTHOR]

The naked characin (Gymnocharacinus bergii) is the only endemic fish of the arid Patagonia of Argentina, living only in the thermal headwaters of the Valcheta Stream in the Somuncura Plateau. This species is listed as Critically Endangered on the IUCN Red List.In April 2018, a massive mortality event was observed in the species. Parasitological studies identified the cause as an epidemic of white spot disease, caused by the parasite Ichthyophthirius multifiliis (Ich).Ich is a common disease in aquaculture settings, but it has also been reported as an epizootic in wild fish populations across tropical and temperate regions worldwide. This occurrence is associated with the introduction of fish into non‐native environments.This article presents the first recorded instance of a mass mortality event and Ich outbreak in the naked characin. It includes a mapping of the disease in the headwaters of the stream, an estimation of the impact on the species' population size, and an analysis of potential causes associated with this epidemic.The results indicate that the epizootic produced mortality of 82% of the global population of the naked characin and was linked to the presence and high abundances of the invasive fish species Uruguay tetra (Cheirodon interruptus). The disease occurred in stream sectors where both characid species coexist, particularly in areas with the highest water temperatures.The Ich outbreak represents the most recent and severe threat recorded for the Critically Endangered naked characin. Implementing control measures against the invasive Uruguay tetra is imperative to prevent future outbreaks that could push the species to the brink of extinction in the near future.This study provides crucial information for assessing current management interventions and developing new strategies within the framework of the action plan for naked characin conservation. [ABSTRACT FROM AUTHOR]

Fred Utter died in his sleep during the night of 5 March 2023 at the age of 91. In this paper, 3 friends and colleagues of Fred describe the important role that his genetics research has played in the management and conservation of fish populations. [ABSTRACT FROM AUTHOR]

Objective: A recent expansion of the northern stock of Black Sea Bass Centropristis striata into the northern Gulf of Maine raises questions about this species' movement and population dynamics in this region. Determining the origin of these fish is essential, as dramatic changes in migration patterns or current population boundaries could have profound effects on stock assessment estimates and subsequent management regulations. Methods: In this study, we measured otolith core concentrations of stable isotopes (δ18O, δ13C) and trace element:calcium ratios (Mg:Ca, Mn:Ca, Cu:Ca, Zn:Ca, Ba:Ca, Sr:Ca) to assess the natal origin of Black Sea Bass that were caught off the coast of Maine. Spawning condition adults from southern New England (SNE) and the mid‐Atlantic Bight (MAB) were used to characterize the chemical fingerprint of these known spawning regions. Result: Unique chemical fingerprints were identified for fish from SNE and the MAB, with high reclassification success using random forest analysis (16% error rate). The classification of Black Sea Bass of unknown origin that were caught in Maine waters indicated that 85% of the samples matched to SNE and 13% to the MAB, whereas one sample remained unclassified. Conclusion: Results from this study support the current management population separation of the northern stock of Black Sea Bass between SNE and the MAB and lends additional information to the understanding of this species' movement into the northern Gulf of Maine. As fish stocks around the world continue to shift into new regions due to climate change, knowledge of their natal origin will be critical to long‐term sustainable management of this species. Impact statementDetermining which population Black Sea Bass located in Maine came from helps scientists understand how these fish migrated there, their potential for success, and their expected growth and maturity. If this species becomes more abundant in the region, this information could help inform regulation surrounding conservation and fishing practices. [ABSTRACT FROM AUTHOR]

Understanding the patterns of genetic diversity of species and precise stock identification are important in fisheries conservation management. However, studies on genetic diversity, connectivity, population structure, and gene flow of groupers within the Indo-Malaya Archipelago (IMA) waters are limited. The objective of the present study was to examine the phylogeographic patterns of the family Epinephelidae in IMA waters based on a parallel study of five selected species utilizing the mitochondrial COI. The grouper species were: areolate grouper (Epinephelus areolatus), blacktip grouper (Epinephelus fasciatus), sixbar grouper (Epinephelus sexfasciatus), blue-lined hind (Cephalopholis formosa), and white-edged lyretail (Variola albimarginata). Specimens were obtained from fish landing sites and fish markets from 23 locations throughout the IMA waters. This study showed genetic structuring for two species (Epinephelus areolatus and Variola albimarginata) but genetic homogeneity for the other three investigated species across IMA. Various geological and demographic histories, local and regional oceanographic features, and biological characteristics are hypothesized to shape the present genetic pattern of each species across the IMA waters. The establishment of effective international cooperation is encouraged to manage grouper species stocks in this region. [ABSTRACT FROM AUTHOR]

Riverine systems and associated fish populations worldwide are threatened by human impacts, especially in tropical countries with emerging economies. In India, community-based fish sanctuaries are a key mechanism for the conservation of freshwater fish populations, but there are few peer-reviewed studies on this subject. Here we integrate over 35 combined years of field experience with a literature synthesis to define and classify community-based fish sanctuaries. We present a novel, critical analysis of fish sanctuaries as social–ecological systems with a functional characterization based on natural capital, ecosystem services, human well-being, and policy and governance. We find that such sanctuaries are shaped by complex social–ecological processes, including coevolution of religious practices and ecological change, feedback processes created by retaliatory conflicts between river users, and diverse and dynamic governance strategies. These sanctuaries hold great potential for the conservation of rare fish species in India, but are subject to myriad threats at local, regional and global scales. Given the complexity of these social–ecological systems, we outline their conservation potential and highlight directions for future research. [ABSTRACT FROM AUTHOR]

The length-weight relationship parameter is important for obtaining fish weight and biomass data with relevant implications about species role on ecosystem functioning. Here we report the length-weight relationship (LWR) for 24 fish species from three streams located in the Atlantic Forest in the Rio de Janeiro State, Brazil. Fish were collected with electrofishing and standard length (cm) and wet weight (g) were measured to obtain the a and b parameters of the Log (W) = Log (a) + b Log (SL) equation. Length-weight relationships for seven out of 24 species (Hypostomus punctatus, Deuterodon taeniatus, Deuterodon hastatus, Deutorodon janeiroensis, Characidium vidali, Characidium interruptum and Rineloricaria zawadiskii) are reported for the first time. The length-weight relationships reported here contribute to the database that can support fish diversity conservation, fisheries management plans and studies on fish biology. [ABSTRACT FROM AUTHOR]

The present work is aimed to assess the water quality parameter of Gomti river and its relation with ichthyofaunal diversity data and it revealed that only 56 fish species identified in middle stretch of Gomti river and representing 20 families with 37 fish genus. Out of the total 56 fish species only 6 species are exotic fish species. The higher relative abundance was found in small size fishes and IUCN status of threaten categories fishes were also assessed to know the conservation status of fishes. Various fish diversity indexes were measured to evaluate the diversity pattern of fishes and their distribution structure as per ecological point of view like Simpson's diversity index, Shannon_H diversity, Piclou's Evenness equitability index and Magalef diversity index. [ABSTRACT FROM AUTHOR]

Aim: Biodiversity changes can occur gradually or as distinct jumps as species distributions end and others begin. However, comprehensive assessments of freshwater biodiversity and how assemblages change along a continuum have been hindered by the connectivity and networked nature of streams and their large numbers of rare and cryptic species found there. We hypothesize that the boundary where fish distributions end marks an ecological shift in freshwater assemblages and could unify stream concepts. Location: Trask River watershed, Oregon, USA, temperate North America. Taxon: Fishes, amphibians, crayfishes, bivalves, mammals, pathogens. Methods: We targeted freshwater species across taxa using multigene eDNA metabarcoding of 48 different DNA barcodes to identify assemblages to understand species patterns distributed along a longitudinal gradient in watersheds around the upper fish distribution boundary. Detections from multiple genetic sources improve the detection probability for rare species. Results: We detected a shift in the assemblage from lower reaches towards headwaters where fish distributions end, leading to fewer species across taxa at reduced eDNA signal. We uncovered a hidden biodiversity in watersheds by detecting a sparsely distributed amphibian pathogen Batrachochytrium dendrobatidis, the elusive mammal Mountain Beaver, fish species that went undetected using traditional approaches, and newly discovered cryptic lineages of sculpins. Salmonids were detected further upstream with eDNA than expected. Main conclusions Our findings unify stream concepts owing to the marked species shift at the upper extent of fish elevating the importance of this boundary. The detection of salmonids further upstream suggests a distribution extension. The sculpin detections reveal a cryptic species complex with ramifications for fish conservation, potential pockets of endemism and possible identification of new species. We show extensive diversity in watersheds, some of which was previously hidden, transforming our understanding of species presence and distributions affecting our ability to track, protect and manage them across watersheds. [ABSTRACT FROM AUTHOR]

The introduction of non-native fish species poses a threat to native assemblages in floodplain systems. Establishing oxbow lake-based conservation areas has been proposed as a practical approach to mitigate this threat. Previous studies have extensively discussed the effects of lateral connectivity between oxbow lakes and main channels on fish communities but overlooked the spatial longitudinal gradients of oxbow lakes on a broader spatial scale. Over the course of about ten years, the temporal changes in fish community diversity were estimated in 28 oxbow lakes along the Ishikari River in Hokkaido, Japan. The associations between these temporal variations and the locations of the lakes were then explored along a longitudinal spatial gradient. The results showed that upstream oxbow lakes underwent mild alterations to their species composition and maintained a high level of native uniqueness. In contrast, downstream oxbow lakes experienced intense species turnover and increased non-native fish diversity. Additionally, the dominance of non-native fish in downstream areas rapidly expanded upstream to a location 110 km from the source of the Ishikari River over the decade. It is emphasized that the lakes in the upper reaches were the only remaining refuges for native fish and should be prioritized in conservation efforts. Our study proposes the application of location and species contributions to regional community heterogeneity as indicators for highlighting native fish conservation areas. [ABSTRACT FROM AUTHOR]

Large cichlids of the genera Oreochromis, Tilapia, Serranochromis and Sargochromis are the backbone of the gillnet fishery of the Zambezi River, but Oreochromis spp. is currently over‐exploited and at risk of local extinction. As a result, the Sikunga Fish Protected Area was established in 2012 to restore a decline in fish stocks of the Zambezi River, but its efficiency has never been assessed. The aim of this study was to compare fish assemblages, abundance and mean sizes between a fish protected area (Sikunga FPA) and nonprotected areas; the Sikunga Buffer Zone and the Lisikili Fished Area on the Zambezi River. Monthly gillnet surveys, using commercial gillnets, were conducted from July to December 2020. Overall catch rate (CPUE) by weight of all species differed significantly among the sampling sites (Kruskal–Wallis H‐test, range χ2(2) = −27.95, p = 0.0001). The highest CPUE was recorded at Sikunga Fish Protected Area (2.85 kg/set ± 0.42 (SE)), followed by the Sikunga Buffer Zone (0.93 kg/set ± 0.16 (SE)) and the Lisikili Fished Area (0.61 kg/set ± 0.14 (SE)). Further analyses showed that the mean sizes of O. andersonii, Coptodon rendalli, Serranochromis and macrocephalus were significantly larger at the Sikunga Fish Protected Area than at the Lisikili Fished Area. A particularly interesting observation pertains to a lack of variation in catch rates of Serranochromis macrocephalus and mean sizes of Clarias gariepinus between the protected and nonprotected areas, signifying that fish protected areas can be species‐specific, and not all species in a water body will respond positively to protection. The overall results of this study support the innovation of fish protected areas as a fundamental tool in attaining sustainable management of fishery resources in inland waters of Namibia and other developing countries. [ABSTRACT FROM AUTHOR]

Dispersal of eggs and larvae from spawning sites is critical to the population dynamics and conservation of marine fishes. For overfished species like critically endangered Nassau grouper (Epinephelus striatus), recovery depends on the fate of eggs spawned at the few remaining aggregation sites. Biophysical models can predict larval dispersal, yet these rely on assumed values of key parameters, such as diffusion and mortality rates, which have historically been difficult or impossible to estimate. We used in situ imaging to record three-dimensional positions of individual eggs and larvae in proximity to oceanographic drifters released into egg plumes from the largest known Nassau grouper spawning aggregation. We then estimated a diffusion–mortality model and applied it to previous years' drifter tracks to evaluate the possibility of retention versus export to nearby sites within 5 days of spawning. Results indicate that larvae were retained locally in 2011 and 2017, with 2011 recruitment being a substantial driver of population recovery on Little Cayman. Export to a nearby island with a depleted population occurred in 2016. After two decades of protection, the population appears to be self-replenishing but also capable of seeding recruitment in the region, supporting calls to incorporate spawning aggregation protections into fisheries management. [ABSTRACT FROM AUTHOR]

Here, we present the results of a large-scale fish rescue prior to the building of flood protection structures along a stretch of the River Svratka running through Brno city centre (Moravia, Czech Republic). During this demanding and unique event, 5,861 fish, with a total weight of 1,951 kg, were caught and successfully transferred downstream. A total of 21 species of fish were recorded, of which two were protected species and two non-native to the Czech Republic. The dominant species caught (i.e. > 10%) were chub (Squalius cephalus), nase (Chondrostoma nasus), roach (Rutilus rutilus) and vimba bream (Vimba vimba), making up 85% of the catch. While this stretch of the Svratka supported a type-specific fish community dominated by rheophilic species, the occurrence of many species was supported through stocking by the Moravian Anglers Association. The length-frequency distribution of individual fish species suggests there has been a lack of recruitment over a relatively long period. This is most likely linked with hydropeaking from the Brno reservoir water power plant, with daily sharp fluctuations in flow in a river channel lacking shallow bankside areas and refuges with slowflowing water preventing fish fry survival. [ABSTRACT FROM AUTHOR]

There are many syntheses on the role of animal behavior in understanding and mitigating conservation threats for wildlife. That body of work has inspired the development of a new discipline called conservation behavior. Yet, the majority of those synthetic papers focus on non-fish taxa such as birds and mammals. Many fish populations are subject to intensive exploitation and management and for decades researchers have used concepts and knowledge from animal behavior to support management and conservation actions. Dr. David L. G. Noakes is an influential ethologist who did much foundational work related to illustrating how behavior was relevant to the management and conservation of wild fish. We pay tribute to the late Dr. Noakes by summarizing the relevance of animal behavior to fisheries management and conservation. To do so, we first consider what behavior has revealed about how fish respond to key threats such as habitat alteration and loss, invasive species, climate change, pollution, and exploitation. We then consider how behavior has informed the application of common management interventions such as protected areas and spatial planning, stock enhancement, and restoration of habitat and connectivity. Our synthesis focuses on the totality of the field but includes reflections on the specific contributions of Dr. Noakes. Themes emerging from his approach include the value of fundamental research, management-scale experiments, and bridging behavior, physiology, and ecology. Animal behavior plays a key role in understanding and mitigating threats to wild fish populations and will become more important with the increasing pressures facing aquatic ecosystems. Fortunately, the toolbox for studying behavior is expanding, with technological and analytical advances revolutionizing our understanding of wild fish and generating new knowledge for fisheries managers and conservation practitioners. [ABSTRACT FROM AUTHOR]

The thornback ray (Raja clavata) is the most important chondrichthyan in terms of landings in the Mediterranean Sea. Intense harvesting may induce negative genetic effects reducing the resilience of overfished species. For this reason, genetic diversity information should be considered in fisheries management and conservation policies.Microsatellite markers were used to unravel the genetic features (variability, connectivity, sex‐biased dispersal) of R. clavata populations, both at the small (around the coast of Sardinia, western Mediterranean Sea) and larger spatial scales (at the pan‐Mediterranean level, and between the Atlantic Ocean and the Mediterranean Sea).Individual clustering, multivariate and variance analyses rejected the hypothesis of genetic homogeneity, with significant genetic differences between Mediterranean and Atlantic rays, as well as within the Mediterranean Sea between its western and eastern basins. The data indicated that both the Strait of Gibraltar and the Sicilian Channel seem to be effective in limiting the dispersal of thornback ray individuals, but a further structuring was identified, with the significant genetic differentiation of the populations located in the Algero‐Provençal and Tyrrhenian basins. Such a fine‐scale arrangement suggests the occurrence of additional barriers to species dispersal. A lack of significant genetic differentiation, stable over the years, was measured at a local scale among R. clavata Sardinian samples.Several possible mechanisms, both biological and abiotic (e.g. migratory behaviour, waterfronts and oceanographic discontinuities), are discussed. Overall, the genetic data presented, both at the local and regional level, could represent the baseline information for the temporal monitoring of populations and assessing the effects of present or future fisheries‐related management actions.The data obtained are information of paramount importance for minimizing the gaps in our current knowledge of the genetic diversity of thornback rays and maximizing the information needed for the correct protection of R. clavata populations. [ABSTRACT FROM AUTHOR]

This paper applies the von Bertalanffy growth equation to study the age structure and growth characteristics of 210 Ptychobarbus dipogon collected in September 2019 in the middle and upper reaches of the Yarlung Zangbo River and employs FISAT II software to estimate the population characteristics' parameters. Its aim is to provide a basis for the conservation of the population resources of the Ptychobarbus dipogon. In this study, the length of the catch ranged from 137 mm to 475 mm, the weight ranged from 44.04 g to 1142.80 g, the minimum age was 5 years, and the maximum age was 47 years. The body length–weight relationship was W(♀) = 4.1738 × 10−5L2.7687 (n = 86, R2 = 0.901); W(♂) = 2.7784 × 10−5L2.8434 (n = 100, R2 = 0.918). The growth equation was Lt(♀) = 505.000[1 − e−0.048(t−1.992)]; Lt(♂) = 452.254[1 − e−0.069(t−4.233)]; Wt(♀) = 1296.576[1 − e−0.048(t−1.992)]2.7687; Wt(♂) = 1001.872[1 − e−0.069(t−4.233)]2.8434. The inflection point ages of the female and male Ptychobarbus dipogon were 7.95 and 6.05, respectively. The exploitation rate of Ptychobarbus dipogon was 0.61, which exceeds the optimum exploitation rate of resources (0.57). The population resources are overfished. It is suggested to strengthen the conservation of Ptychobarbus dipogon population resources and the protection of native fish on the Qinghai–Tibet Plateau. [ABSTRACT FROM AUTHOR]

This study provides the first socio-ecological overview of the Seriola dumerili fishery occurring in the Balearic Islands. This pelagic top-predator is among the five most valued fish resources of the Balearic community. Despite its ecological importance and potential vulnerability to aggregation fishing, few studies address the ecology of this large Carangidae species. Shining a light on its ecology is vital to ensure adequate species conservation and the sustainable and effective management of the fishery. Historical catches from 1950–1999, alongside detailed landing data for the last 21 years, were analysed to identify potential patterns in ecological and socio-economic factors. Significant inter-annual variability among the years was found in historical catches of greater amberjack, while catches and mean prices of the different size categories revealed significant results between seasons and months, respectively. Additionally, the purse seine fleet accounted for the highest percentage of S. dumerili catches. CPUE did not appear to change greatly between months and years after the annual 8-month fishing ban imposed in 2011 and therefore a re-evaluation of the closure was intended. Overall, this study suggests seasonality influences the S. dumerili fishery in the Balearic Islands, within which ecological influences show a higher regulating power than socio-economic factors. [ABSTRACT FROM AUTHOR]

Inland fishing is an essential activity for the livelihood and food security the Colombian population. The knowledge and evaluation of exploited fish stocks is a priority to develop sustainable management and conservation strategies of the fisheries. To optimize the management processes of fishery resources and conservation of species, it is necessary to evaluate the population structure and identification of stocks. Geometric morphometrics analysis have shown useful in the evaluation of fish stocks. This study focuses on the species Plagioscion magdalenae, commonly called "Pacora", corvinata, or river croaker, which belongs to the family Sciaenidae, a family characterized as an important fishery resource. With the aim of generating a baseline about the state of the P. magdalenae population structure, samples were collected along the marshy complex of the Dique channel, Colombia, between December 2020 and October 2021. In this study, the existence of morphometric variability between individuals of Plagioscion magdalenae was found across sampling sites, Ciénaga de Capote and Ciénaga del Jobo; shape differences between location suggest the action of environmental pressures and the existence of anthropogenic pressures, such as unsustainable artisanal fishing. [ABSTRACT FROM AUTHOR]

Interbreeding between various fish populations or species is known as hybridization, and it significantly affects fish taxonomy and conservation tactics. By producing individuals with intermediate features, hybridization in the field of ichthyology challenges conventional ideas of species boundaries and blurs the borders between species. Additionally, it unearths cryptic species and previously undetected genetic diversity. Occasionally, it can also result in taxonomic inflation, which makes it more difficult to classify fish species. Hybridization threatens endangered species by compromising their genetic integrity and can lead to genetic erosion within native populations, both of which negatively affect conservation. For environmentalists, maintaining genetic integrity while accepting hybridization as a natural process remains a difficult task. By encouraging range changes and modifying ecosystems, climate change intensifies these processes by expanding the window of opportunity for hybridization. In light of changing environments, it is crucial to understand how hybridization affects fish taxonomy and conservation. Adaptability, continual study, and a dedication to maintaining the great range of fish species in our planet's aquatic ecosystems are necessary for effective conservation methods. [ABSTRACT FROM AUTHOR]

The eleventh session of the SAG of the WECAFC was held virtually from 25-27 April 2022. The SAG considered the outcomes of the work carried out by various joint Working Groups (WG) between 2019 and 2022 and their recommendations to the 18th Session of WECAFC (WECAFC18). The SAG also reviewed the status of the main fish stocks in Areas 31 and 41. A revised version (v0.8) of the Data Collection Reference Framework (iDCRF) was also reviewed. During the meeting, the Working Groups and other regional experts presented reviews of draft fishery management plans and regional strategies, regional plan of action, as well as a guide and a study, as follows: • reviews: State of fisheries and aquaculture in the WECAFC region; Biological data, the stocks spatial distribution and the ecological connectivity between the areas beyond national jurisdiction and the exclusive economic zones in the WECAFC region; • fishery management plan: A draft on regional fish spawning aggregation fishery management plan (FSAMP) with focus on nassau grouper and mutton snapper; A draft Caribbean Regional Management Plan for the anchored (moored) fish aggregating device (aFAD); • regional Strategy: A draft on the Management of bycatch and discards in Latin American and Caribbean WECAFC bottom trawl (shrimp and groundfish) fisheries; • regional Plan of Action: A draft for the Conservation and Management of Sharks, Rays and Chimeras in the WECAFC area; • guide: WECAFC guide for improved monitoring of aFAD catches and improved assessment of aFAD impact on stocks; and • study: A study on health and safety in the dive fisheries of key species in the WECAFC region (Technical report). Additionally, there was a review by the SAG of outputs from activities of the multiple WGs during the intersession, as summarized in the reports of the respective WGs, which also included draft recommendations to the 18th session of WECAFC, tailored terms of reference and 2022-2024 workplans. A list of specific SAG recommendations for the attention of WECAFC18 is included in the preface of the report. Tailored terms of reference and workplans for 2022-2024 are provided for each WG as appendixes. [ABSTRACT FROM AUTHOR]

Simple Summary: In recent decades, societies, states and local authorities have become increasingly aware that for effective long-term management and protection of aquatic ecosystems and populations, it is necessary to take into account the genetic changes occurring in these populations. One type of high-resolution molecular marker suitable for studying the neutral and adaptive genetic diversity of populations is single nucleotide polymorphism (SNP). This review is an attempt to show the benefits of using SNPs to recognize natural populations of aquatic animals and detect the threats to them from accidentally or intentionally released farm animals, fishery and global climate changes. It is postulated that conservation actions should protect not only pristine natural populations that are endangered or overfished, but also protect populations of non-threatened species from unnecessarily released semi-domesticated animals. The enhancement of natural populations with farmed material usually reduces their genetic diversity. Experimental size-selective catches of artificially created populations have caused evolutionary changes in the life cycles of fishes. However, fishery-induced evolution in natural populations is difficult to observe. The negative measurable effects on populations can be expected when the number of breeding individuals is reduced below 100, which occurs very rarely in the sea and more often in fragmented freshwater streams, ponds and seasonal rivers. An increasing number of aquatic species have been studied for genetic polymorphism, which extends the knowledge on their natural populations. One type of high-resolution molecular marker suitable for studying the genetic diversity of large numbers of individuals is single nucleotide polymorphism (SNP). This review is an attempt to show the range of applications of SNPs in studies of natural populations of aquatic animals. In recent years, SNPs have been used in the genetic analysis of wild and enhanced fish and invertebrate populations in natural habitats, exploited migratory species in the oceans, migratory anadromous and freshwater fish and demersal species. SNPs have been used for the identification of species and their hybrids in natural environments, to study the genetic consequences of restocking for conservation purposes and the negative effects on natural populations of fish accidentally escaping from culture. SNPs are very useful for identifying genomic regions correlated with phenotypic variants relevant for wildlife protection, management and aquaculture. Experimental size-selective catches of populations created in tanks have caused evolutionary changes in life cycles of fishes. The research results have been discussed to clarify whether the fish populations in natural conditions can undergo changes due to selective harvesting targeting the fastest-growing fishes. [ABSTRACT FROM AUTHOR]

Ecosystem-based management is costly. Therefore, without rigorously showing that it can outperform traditional species-focused alternatives, its broad-scale adoption in conservation is unlikely. We present a large-scale replicated and controlled set of whole-lake experiments in fish conservation (20 lakes monitored over 6 years with more than 150,000 fish sampled) to examine the outcomes of ecosystem-based habitat enhancement (coarse woody habitat addition and shallow littoral zone creation) versus a widespread, species-focused alternative that has long dominated fisheries management practice (i.e., fish stocking). Adding coarse woody habitats alone did not, on average, enhance fish abundance, but creating shallow water habitat consistently did, especially for juvenile fish. Species-focused fish stocking completely failed. We provide strong evidence questioning the performance of species-focused conservation actions in aquatic ecosystems and instead recommend ecosystem-based management of key habitats. [ABSTRACT FROM AUTHOR]

Dams are undoubtedly a primary threat to global freshwater fishes. However, how fish functional traits respond to dams at the global scale remains poorly understood, which hinders a general understanding of related ecological processes, conservation, and management. By synthesizing fish data from 4040 relevant publications, this study investigates the species compositional and functional differences before and after dam construction, aiming to obtain general fish response patterns to dams and to propose pertinent conservation suggestions. The mean values of body size and trophic level of the occurrence-increased (OI) fishes and occurrence-decreased (OD) fishes were found to be larger than those of global freshwater fishes obtained from FishBase, respectively. In terms of mouth orientation, most OI fishes have terminal mouths, while a large proportion of the OD fishes have inferior mouths. The sensitive functional traits that respond to dams are habitat preferences and reproductive traits because the OI fishes are mainly lentic-adapted, warm-water, non-migratory, and produce demersal eggs, while the majority of the OD fishes are lotic-adapted, cold-water, migratory, and produce floating eggs. These results indicate that functional trait-based evaluations are essential for predicting the impacts of dam development on fish assemblages and guiding global biodiversity conservation, management, and sustainability. [ABSTRACT FROM AUTHOR]

Fish-protection screens for water pumps and channels can conserve fish populations and deliver operational benefits to irrigators. However, the uptake of fish screens is mixed, and there is limited evidence concerning irrigator attitudes towards this technology. The current study addresses this knowledge deficit through 26 semi-structured in-depth interviews with irrigators and other associated water users. The purpose of this study was to understand pump screening practices and experiences, the current level of awareness of fish-screening options, attitudes towards potential environmental and financial benefits, overall intentions to install fish screens, the role of attitudes and other factors in impacting these intentions, and critical fish screening knowledge gaps and communication preferences. Drawing on the theoretical framework of Diffusion of Innovations (DOI), the study identified that irrigators have low awareness of native fish loss and the benefits of fish screening. However, they are interested in learning more about the economic, social, and environmental benefits of fish screen adoption. Customised communications and education programs are needed to increase intentions to install fish screens in Australia. [ABSTRACT FROM AUTHOR]

The fish diversity of the Kundelungu National Park (KNP), one of the seven national parks of the Democratic Republic of the Congo, has never been thoroughly studied. This first checklist is presented based on a literature compilation and the study of historical (1939–1969) and recent collections (2012–2017). A total of 96 taxa are reported, including 64 native described species, one introduced species (Poecilia reticulata), 13 new species that await formal description and 18 possibly new species that require further investigation to verify their status. These taxa represent 39 genera and 17 families from the KNP including its Buffer Zone (BZ). Only six taxa, including five endemics, are known from the Core Zone on the Kundelungu Plateau (1300–1700 m alt.). At lower altitudes (800–1100 m), in the Annex Zone, 71 taxa, including 17 endemics, were found. Finally, 50 taxa, including 13 endemics and one introduced species, are known from its BZ. The fish fauna of the KNP is threatened by overfishing, destructive fishing practices, and habitat degradation due to mining pollution, and deforestation for agriculture on the river banks. The present study provides the much needed baseline data for the protection and conservation planning of this fish fauna, for which conservation suggestions are formulated. [ABSTRACT FROM AUTHOR]

Management regimes of marine resources that rely on spatial boundaries might be poorly adapted to climate change shifts in species distributions. This is of specific concern for the management of fish stocks that cross management jurisdictions, known as shared stocks. Transitioning to dynamic rules in spatial management has been suggested as a solution for mismatches between species distributions and the spatial boundaries. However, in many cases spatial boundaries are not clearly drawn, hampering such transitions. Here, we use black sea bass (Centropristis striata), summer flounder (Paralichthys dentatus) and scup (Stenotomus chrysops) as case studies to explore different approaches to designing spatial regulatory units to facilitate the adaptation of fisheries management to shifting distributions of shared stocks. First, we determine the yearly distribution of each stock within the United States Exclusive Economic Zone from 1951 to 2019 during Fall and Spring sampling seasons. Second, we explore two approaches for drawing regulatory units based on state waters and historical landings. Finally, we estimate each state's proportion of the stock's distribution and compare historical and recent values. We show that the distribution of all three stocks has changed relative to the years used to determine the current quota allocation across states, with an overall gain for central-northern states at the expense of the southernmost states. In terms of the distribution of allocation, we find that, while seasonal differences exist, the biggest differences in the proportion of the stock spatial distribution attributed to each state come from the method for designing regulatory units. Here, we show that the method used to define allocation units can have meaningful impacts on resulting adaptive policy. As climate change-driven conflicts in fishing resource allocation are expected to increase and deepen around the world, we provide a replicable approach to make an informed and transparent choice to support data-driven decision-making. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the population dynamics of medaka fish (Oryzias nigrimas) in Lake Poso. Three habitats of this fish were surveyed, including Watudilana waters, Tolambo village waters and Taipa village waters. Samples were collected at night using a petromax lamp to attract fish. The fishing gear used nets of 8 by 3 meters with a mesh size of 3 by 3 millimeters. A total of 685 individuals of medaka fish (Oryzias nigrimas) were used for population dynamics analysis. Standard length was used to compare the current size of the endemic medaka fish Oryzias nigrimas with its size 28 years ago, while total length was used to examine data on growth, mortality, exploitation rate, recruitment yield and potential reproductive ratio. The male to female sex ratio of this type of fish fluctuated each month, where females tended to be more abundant than males. The average length of this fish is smaller than the standard length in 1993. However, its average size is larger than the freshwater medaka species Oryzias asinua, Oryzias wolasi and Oryzias woworae from Southeast Sulawesi and Oryzias matanensis from Lake Sulaw Towuti. The mortality rate of the medaka fish Oryzias nigrimas is mainly caused by the presence of introduced species and overexploitation. Selectivity of fishing gear, especially by catching fish measuring more than 50.70 millimeters, is strongly recommended for the conservation effort of this fish species. [ABSTRACT FROM AUTHOR]

Analysis of long-term data provides a valuable approach to determining the extent of biodiversity decline and likely causes, but such approaches are rare in large tropical rivers. We investigated the response of the fish fauna to hydrological, climate and anthropogenic factors over the period 1982–2017 in the lower Ganges (Padma) River, Bangladesh. Systematic effort-based sampling of fish between 2007 and 2017 from a 70-km reach showed a decreasing trend in abundance and diversity. Compared to 1982 data for the same sites and fishing methods, 28 fish species, including 16 nationally threatened ones, were absent in recent catches, suggesting local extinction of these. Fish community diversity was negatively affected by fishing pressure (71 fishermen in 1980, 2616 in 2019, 37.8-fold increase) and non-native species abundance (6.8-fold increase in abundance between 2007 and 2017). Permanent water area has reduced by ~ 50% since 1984. Annual mean rainfall, Ganges water depth and river discharge at the study location decreased significantly since 1980 (by 19.2%, 17.8% and 27.6% respectively, while annual air temperature increased (25.1 °C in 1981 to 26.2 °C in 2019). Water diversion at the Farakka Barrage, ~ 70 km upstream, is partially responsible for reductions in permanent water area in the study reach. Potential sources of biological invasion and water pollution have been identified. Widespread ecological consequences on fish diversity and productivity, resulting from multiple factors, are occurring in the lower Ganges. Reduction of fisheries impacts and improved prevention of accidental aquaculture releases of non-native fishes are identified as conservation priorities for arresting the decline of native fishes in the lower Ganges. [ABSTRACT FROM AUTHOR]

The document provides information about continuing education courses offered at a fisheries conference. The courses cover a range of topics including data visualization, data analysis, genetics, Bayesian inference, and science communication. The instructors come from various institutions and organizations, ensuring diverse perspectives. The courses are offered at different times throughout the conference, and fees vary depending on membership status. [Extracted from the article]

Small-scale fisheries (SSF) make a critical contribution in terms of employment and food security to coastal communities. Fish serves multiple purposes, mainly as a cheap source of protein and minerals for lower-income families. In order to help sustain this demand and to protect fishing resources, the closed season policy, temporal closure, and spatial closure were adopted to protect fish stocks and avoid fishery collapse. To assess the agreement and compliance of the three municipalities (Cortes, Lanuza, and Lianga) in Surigao del Sur to this policy, we surveyed their responses regarding this policy. We used focus group discussions, two focus groups per municipality (N = 80), followed by member checking to gather and clarify the data from six barangays with small-scale fishers (N = 192). The findings indicate that each community in the three municipalities studied have a different method of implementing the fishery closure or closed fishing season policy which resulted in a limited conservation impact on fish stocks. In the municipality of Cortes, 92% agreed with the policy, provided there would be enough money to comply with the policy. In Lanuza, 60% agreed to implement the policy, provided there would be alternative jobs available. In contrast, the municipality of Lianga, which did not implement this policy, had only 4% that agreed to impose the policy to restore depleted fish stocks. Other reasons for not implementing a closed season policy include lack of community organization, poor fishery management, and lack of strong government support for the policy. Moreover, fishers were only willing to stop fishing if they were given a subsidy of PHP 15,000 per month. In the long term, fishers who provide fish protein needs for the nation also need help and attention from policy and decision makers to realize sustainable fisheries. [ABSTRACT FROM AUTHOR]

In Romania, the main commercial fish species reported by the commercial fishermen were carp, sturgeon, catfish, shads, zander, pike, pontic shad and turbot. If at the beginning of the 20th century the quantities reported by commercial fishermen were on average 19,287 tonnes year-1, in the period 1990-2021 they reached at only 3,277 average tonnes year-1. The commercial catches of the main commercial fish species, Cyprinus carpio, decreased by almost 95%, from 6 thousand tonnes in 1909 to only 142 tonnes after a century. The main causes that have affected wild fish populations are overfishing, disruption of migration routes, destruction of spawning and feeding grounds, through the construction of dikes and dams. Practically, in the last century fish populations have been overexploited, creating an imbalance between total mortality and natural productivity, so that some species have been severely affected and others have even disappeared. In such a situation, where the fish stocks are rapidly declining, fisheries management must intervene with concrete measures to ensure a sustainable level of fishing mortality, by reducing fishing effort, wetland renaturation and by promoting a multiannual program for restoking and stock enhancement. First, the legal framework must be adapted as a basis for any repopulation or supportive action in natural waterbodies from Romania, to plan and coordinate in the short, medium and long term the multi-annual program for restoking and stock enhancement, in natural waterbodies. [ABSTRACT FROM AUTHOR]