This qualitative study examined the integration of Artificial Intelligence (AI) in sustainable freshwater fishery management within the Okavango River ecosystem, combining primary field research with a comprehensive document review. The investigation explored how AI technologies, including machine learning and predictive analytics, can enhance fish stock assessment, habitat monitoring, and resource administration to achieve ecological and socio-economic sustainability. The study emphasizes the Okavango River's unique biodiversity and its critical importance to local communities while assessing AI's potential to transform traditional fishery management approaches. The research employs a dual-method approach, utilizing both face-to-face semi-structured interviews with key stakeholders (fishers, vendors, and officials) and a systematic review of relevant policy documents and documentary reviews. Thematic analysis of interview data and document content reveals key insights about AI adoption challenges, implementation opportunities, and practical applications in freshwater fisheries. Findings demonstrate AI's transformative potential in enabling real-time data collection, predictive population modeling, and overfishing prevention. However, significant barriers emerge, including technological infrastructure gaps, institutional resistance, and capacity-building needs among local stakeholders. By synthesizing field data with existing literature, this study makes a novel contribution to sustainable fishery management discourse, offering context-specific, AI-integrated strategies for the Okavango River ecosystem. The research proposes policy recommendations that address both technical implementation challenges and ethical considerations, grounded in empirical evidence from multiple data sources. Ultimately, this study highlights the critical role of AI in balancing ecosystem conservation with socio-economic development, while demonstrating how mixed-method approaches can strengthen research outcomes in environmental technology studies.

In the recent decade, local fishers in the Jammer Bay, western Skagerrak, experienced declining landings of cod ( Gadus morhua ) and plaice ( Pleuronectes platessa ) and were unable to fish up their quotas making it difficult to earn a livelihood. To enable an Ecosystem Based approach to Management (EBM), we applied the Systems Approach Framework (SAF). The fishers' concerns and perceptions of the system were brought forward and integrated into the analysis. We examined whether the declined coastal landings were due to over-fishing, changes in adult cod and plaice distribution, climate change or discards. To address these issues, we integrated data from different, sources including international landings data for Skagerrak, fisheries survey data for the Greater North Sea, Danish landings data and hydrographic models of thermal seabed habitats for the Jammer Bay area, and Danish landings and discards data from the Skagerrak. Our results showed that declines in landings of cod and plaice in the Skagerrak appeared unrelated to quotas and effort. The fisheries survey data showed a regional shift in adult cod and plaice distribution from the southern and central North Sea areas to the northern North Sea areas. However, in the Jammer Bay area changes in where adult cod were caught were related to the distribution of suitable thermal habitats. No effects of changes in thermal seabed habitat were evident for adult plaice. The fisheries survey data showed that juveniles of both species occurred in high densities in the Jammer Bay area as compared to the remaining Skagerrak area and adjacent seas. Their occurrence coincided with the areas that were intensively fished, and high discards of juvenile cod and plaice were registered in the area during the period of the study. These results pointed to the need to implement protection measures for the juveniles of both species. The implementation of an Other Effective Area-based Conservation Measure (OECM) would allow spatio-temporal closures to protect the juveniles while maintaining sustainable fisheries. In this study, we demonstrate how multi-sourced empirical data can be mobilized to provide knowledge-based advice for OECM implementation.

In our study (Suppl. material 1), we aimed to characterize the diet composition of the strictly protected Eurasian otter ( Lutra lutra ) by analyzing fish scales and pharyngeal teeth found in its feces (spraints). As a sampling site, we selected the Marótvölgyi Canal, one of Hungary’s most important habitats for the European mudminnow ( Umbra krameri ). The samples collected originated from different years and seasons, providing a broad temporal overview. Due to the long-term fish monitoring program of the Balaton Limnological Research Institute, the fish fauna of the area is well-documented. However, further insights into the dietary preferences of local piscivorous animals, including otters, can be gained through the identification of fish scale remains in their spraints. In contrast to areas with large fish resources, the otter's diet in this canal includes a large proportion of small mammals, frogs, and water beetles. Preliminary results indicate that scales of the European mudminnow ( Umbra krameri ) were the most frequently occurring from fishes in the samples. The invasive and highly competitive Chinese sleeper ( Perccottus glenii ) was also present in the diet, albeit in lower quantities.

The introduction of the Anthropocene concept reflects humanity's reflection on the accelerated destruction of Earth by human forces. Using fisheries as a case study, the depletion of fish resources and decline in species diversity can be attributed to the combined effects of modernization, marketization, technological innovation, and changing consumption patterns. Within China's modernization journey, the vision of “modernization featuring harmonious coexistence between humanity and nature” emphasizes restorative ecological justice. However, the resource-utilization demands of retired fishermen clash with this approach, trapping livelihood transitions in a stagnant threshold, the foremost challenge in implementing fishing bans. The principle that “the environment is the people's livelihood” can rebuild aquatic ecosystems' regenerative capacity and drive regenerative development in fishing communities. Therefore, guiding fishermen's demands to align with national will during the transition from resource exploitation to ecological restoration is pivotal for achieving both ecological renewal and livelihood transformation. This framework underscores our steadfast dedication to green development while embodying China’s proactive engagement and global accountability in rethinking the Anthropocene.

The Ningxia section of the Yellow River represents a critical habitat for freshwater fish biodiversity, yet its ecological integrity faces increasing threats from anthropogenic activities. To comprehensively assess the fish community structure, diversity, and its relationship with environmental factors in the Ningxia section of the Yellow River, we conducted seasonal surveys of fish resources and environmental conditions at 15 selected sites from July 2022 to September 2023. Our study employed quantitative analyses to evaluate fish community characteristics, spatiotemporal distribution patterns, and their interactions with environmental variables. A total of 42 fish species, belonging to 34 genera, 11 families, and six orders, were identified, with Cyprinidae being the dominant family (57.14%). Carnivorous species were the most abundant (22 species), followed by omnivorous (16 species) and herbivorous (four species) fish. The Relative Importance Index (IRI) identified Gobio huanghensis and Carassius auratus as the dominant species in this region. Biodiversity indices revealed a mean Margalef richness index of 3.066, Pielou evenness index of 0.5911, Shannon-Wiener diversity index of 1.791, and Simpson dominance index of 0.7083. The Abundance-Biomass Comparison (ABC) curve indicated moderate disturbances to fish communities in spring and autumn, while communities remained stable in summer and winter. Spatially, six sites (Nanchangtan, Shapotou, Jinshawan, Meijiawan, Linhe, and Taole) exhibited significant disturbances, while others showed moderate or stable conditions. The results of cluster analysis and non-metric multidimensional scaling (NMDs) indicated no significant differences in fish community structure among the sampling sections in the Ningxia reach of the Yellow River. Redundancy analysis (RDA) identified water temperature and ammonia nitrogen as the primary environmental factors influencing fish community structure. Our findings highlight the combined impacts of human activities and environmental changes on fish communities in the Ningxia section of the Yellow River. These results provide a scientific basis for the conservation and sustainable management of fishery resources in this ecologically sensitive region.

Abstract This study investigates the ecological risk of Halti Beel, one of the significant parts of the largest wetland ecosystem of Bangladesh, following the US Environmental Protection Agency (EPA) ecological risk assessment (ERA) guidelines. Physicochemical parameters of water and sediment were analyzed in reference to Environmental Conservation Rules (ECR) and EPA standards. Socio-economic data from local communities and species data from wetland authorities were integrated through questionnaire surveys. Multispectral satellite imageries were used to evaluate the ecological risks associated with LULC changes from 2000 to 2023. ENVI Thematic Change Workflow (TCW) tool was used for LULC change dynamics analysis over 2000-2010, 2010-2023, and 2000-2023. An ecological risk model was developed using Landscape Ecological Risk Indexes (LERI) in Fragstats 4.2; risk zones were mapped, and risk levels were categorized from minimal to severe. A linear regression analysis in SPSS was done to reveal significant relationships between ecological risk and different stressors. The results indicate that the collected samples’ DO, turbidity and electric conductivity exceed the ECR, 1997, and EPA, 2012 standards. The socio-economic prospects of the area largely depend on fishing, farming, and wetland resources, which support local livelihoods despite growing environmental pressure. However, low education levels, poor sanitation, and unregulated land use challenge the local people’s socioeconomic condition. Most of the environmental and anthropogenic factors have strong connections with ecological risk and leave the current status of species highly vulnerable. The significant LULC transformation: from 2000 to 2023, 55.63 % of deep water was converted into shallow water, 11.68 % to agricultural land, and 19.52% of agricultural land was converted to rural settlements, indicating increasing anthropogenic pressure. Between 2000 and 2010, notable changes are that 60.86 % of deep water was converted into shallow water and 18.54 % shifted to agricultural land. From 2010 to 2023, a major transformation of almost half of the deep water area was converted into shallow water and 9.09 % to agricultural land. Ecological risk fluctuated over time; in 2023 ecological risk spread all over the area and middle, highest, and higher risk areas increased synchronously. Major ecological risk areas shifted to the southwest part of the area. The overall results indicate that ecological risk is increasing evidently.

Small pelagic fish, such as European anchovy ( Engraulis encrasicolus ) and sardine ( Sardina pilchardus ), play a key ecological and economic role in the Adriatic Sea. In recent decades, both species have shown a marked decline in mean body size, raising concerns about the combined impacts of fishing and environmental change. To investigate the main drivers behind this trend, we analyzed 20 years (2000–2021) of fishery-dependent data on weighted mean length ( wML ) derived from Length Frequency Distributions (LFDs) of catches landed in two major Adriatic fishing harbors, Chioggia and Ancona. Generalized Additive Models (GAMs) were applied to explore the relationships between wML , fishing effort and key environmental variables (chlorophyll-a, sea surface temperature, salinity, sea surface height and Po River discharge), incorporating both spatial ( Harbor ) and temporal dimensions ( Time and Season ). Our results indicated that anthropogenic pressures, particularly the interaction between fishing activity ( Fleet ) and long-term temporal dynamics ( Time ), were the dominant contributors to size reduction. This interaction reflects how long-term exploitation patterns have intensified over time despite nominal reductions in fleet size, suggesting cumulative fishing impacts and limited recovery capacity. Environmental variables contributed to explaining the observed patterns but to a lesser extent, suggesting species-specific and spatially structured responses. Overall, this study highlights that historical overexploitation remains the primary driver of body-size decline in the Adriatic small pelagic species. However, the possibly influence of the environmental variables in the dynamics of these species suggest the development of adaptive, ecosystem-based management strategies that integrate historical fishing pressure, current effort distribution and environmental variability to promote the recovery and resilience of these key fishery resources.

Fish diversity and habitat quality assessments were done in Moga Wetland of eastern Uttar Pradesh from November 2023 to April 2024. A total of 23 fish species were collected and were taxonomically identified. The mean values of diversity indices, viz., Simpson’s species richness Index (D), Shannon-Wiener diversity Index (H), Margalef’s Diversity index, and Pielou’s Evenness index (J) in the Wetland were ranged from 0.721 to 0.874, 1.4535 to 2.1942, 1.44062 to 2.4136 and 0.75924 to 0.82612, respectively. The indices showed notable variations between seasons, but that between sampling sites were meagre. The Water quality parameters such as Electrical conductivity (0.76 -0.85 dS/m), salinity (0.36 – 0.43 ppt), DO (3.23 – 3.84 mg/l), free CO2 (10.47 – 13.23 mg/l), TDS (271.4 – 296.3 mg/l), and ammonia-N levels (0.35 – 0.37mg/l) also showed monthly variations. We found a highly varied pattern of correlation between fish abundance and water quality parameters in the wetland, where positive correlations were observed for some parameters in some months and negative correlation in other months, as influenced by monsoon and summer-draught periods. Various habitat disturbances due to human interferences might have also contributed to this complex pattern. The CCA plot showed that pH, salinity, and DO positively influence the distribution of Puntius chola, Anabas testudineus, Cirrhinus mrigala, and Systomus phulo, while ammonia, temperature, and CO₂ favored the presence of Eutropiichthys vacha, Mystus tengra, and Puntius sophore. Higher TDS and EC supported Heteropneustes fossilis, Channa striata, and Trichogaster fasciata, reflecting tolerance to enriched, mineral-rich habitats. Our research provides the first-ever scientific data on fish diversity and its environmental correlatives in Moga Wetland. The findings of this study could be used for framing plans for sustainable utilization and conservation of fish and aquatic resources in wetlands of Central India.Fish diversity and habitat quality assessments were done in Moga Wetland of eastern Uttar Pradesh from November 2023 to April 2024. A total of 23 fish species were collected and were taxonomically identified. The mean values of diversity indices, viz., Simpson’s species richness Index (D), Shannon-Wiener diversity Index (H), Margalef’s Diversity index, and Pielou’s Evenness index (J) in the Wetland were ranged from 0.721 to 0.874, 1.4535 to 2.1942, 1.44062 to 2.4136 and 0.75924 to 0.82612, respectively. The indices showed notable variations between seasons, but that between sampling sites were meagre. The Water quality parameters such as Electrical conductivity (0.76 -0.85 dS/m), salinity (0.36 – 0.43 ppt), DO (3.23 – 3.84 mg/l), free CO2 (10.47 – 13.23 mg/l), TDS (271.4 – 296.3 mg/l), and ammonia-N levels (0.35 – 0.37mg/l) also showed monthly variations. We found a highly varied pattern of correlation between fish abundance and water quality parameters in the wetland, where positive correlations were observed for some parameters in some months and negative correlation in other months, as influenced by monsoon and summer-draught periods. Various habitat disturbances due to human interferences might have also contributed to this complex pattern. The CCA plot showed that pH, salinity, and DO positively influence the distribution of Puntius chola, Anabas testudineus, Cirrhinus mrigala, and Systomus phulo, while ammonia, temperature, and CO₂ favored the presence of Eutropiichthys vacha, Mystus tengra, and Puntius sophore. Higher TDS and EC supported Heteropneustes fossilis, Channa striata, and Trichogaster fasciata, reflecting tolerance to enriched, mineral-rich habitats. Our research provides the first-ever scientific data on fish diversity and its environmental correlatives in Moga Wetland. The findings of this study could be used for framing plans for sustainable utilization and conservation of fish and aquatic resources in wetlands of Central India.

Abstract Xiamen coastal waters are rich in biological resources, with high fish diversity, which is critical for the ecological balance and fishery development. Bottom trawling is a traditional fish resource survey method, but recently, environmental DNA (eDNA) technology has also emerged. This study investigated fish diversity in the coastal waters of Xiamen during autumn using eDNA technology and bottom trawling, comparing the two methodologies. Through sampling and analysis across 13 survey stations, 134 fish species were detected based on eDNA and 75 species were captured via bottom trawling, with a combined total of 163 species belonging to 17 orders, 66 families, and 114 genera. eDNA technology significantly enhanced species detection rates (82.2% of total fish species) compared to bottom trawling (46.0%), enabling the identification of 88 additional species and demonstrating a clear advantage in detecting fish species richness. Alpha diversity analysis indicated that the average Margalef richness index derived from eDNA was significantly higher than that from bottom trawling. However, bottom trawling yielded higher Shannon, Simpson, and Pielou evenness index values compared to eDNA, with the difference in evenness being highly significant. This disparity was likely due primarily to the overwhelming dominance of Johnius belangerii in eDNA detections, which led to reduced community evenness. Beta diversity analysis showed that both methods revealed spatial heterogeneity in the fish community composition among stations. This study demonstrated that combining eDNA technology with traditional bottom trawling provides a more comprehensive assessment of fish diversity, offering a more robust scientific basis for marine ecological monitoring and conservation.

ABSTRACT Narva, located in eastern Estonia by the Narva River between the Baltic Sea and Lake Peipus, was a locus of commerce and active power struggles during the medieval and early modern periods. Although prehistoric faunal deposits show a large diversity in consumption, our knowledge of fish at Narva during the medieval and early modern period is, however, limited. Examining an assemblage of small fish bones together with castle records and customs ledgers from the town of Narva from the late sixteenth century provides a picture of the available fish resources for Narva consumers. The materials show that multiple fish species and products were available to the residents of Narva. While most of the species could be fished nearby, long-distance trade occurred with these species. Seasonal patterns of availability and the use of certain species and products could be identified in this study, as well as social differences regarding fish consumption. This small-scale study shows the research potential in combining primary zooarchaeological data with targeted information from archive records, for the purpose of furthering the environmental and social history of fish; this research method could be more widely adapted to other groups of animals.

Abstract A holistic understanding of social-ecological systems is essential to foster resilient, adaptive, and sustainable marine ecosystems and human communities. Yet, the integration of social and ecological dimensions is still developing within natural resource management, as are the indicators necessary to monitor them. In this study, we assess the integration of social and ecological indicators in marine management through a case study exploring the use of and degree of linkage between social and ecological indicators in US federal environmental and ocean resource agencies. Using a survey, we collected indicator sets or reports developed by these US federal agencies and found that 7 out of 11 total reports contained both social and ecological indicators. Within those reports, there were 333 social indicators. Only 35% (116) of the social indicators could be directly linked to commonly monitored ecological indicators. Social-ecological connections were focused on many themes, including tourism and recreation, fishing and marine resource use, resilience of coastal communities, well-being, cultural/spiritual value, economic impact, environmental and resource management education, and participation in resource management. These results suggest that some integration of social and ecological indicators within the ocean and environmental-focused federal agencies in the US is occurring, but it is not widespread. Exploring and applying methods that facilitate the integration of social and ecological indicators is the next frontier in achieving management of the environment as a combined social-ecological system.

Morphometric and meristic traits offer powerful, cost-effective tools for analysing phenotypic variation, stock structure, and environmental adaptation in freshwater fishes. This review synthesizes findings from more than thirty studies published between 2012 and 2024, covering diverse taxa across Asia, Africa, and the Middle East. The literature reveals strong habitat-driven morphological plasticity, particularly in riverine species exposed to hydrodynamic forces, ecological gradients, and climatic variability. Morphometric traits, which respond rapidly to ecological pressures, consistently differentiated populations of Channa striata, Wallago attu, Schizothorax spp., Clupisoma garua, and several others. Meristic traits, although more genetically stable, also reflected population-level divergence under varied developmental and environmental conditions. Integrating these patterns, the review highlights the importance of morphology for taxonomy, species discovery, biodiversity monitoring, and sustainable fisheries management. Despite methodological challenges—including inconsistent measurement protocols and limited geographic coverage—advances in geometric morphometrics, molecular barcoding, and multivariate analytics have strengthened morphological research. The review emphasizes the need for standardized methodologies and integrated approaches to better understand phenotypic diversity and ensure the conservation of freshwater fish resources in rapidly changing ecosystems.

Most of the people in Bulo Village work as fishermen. Fish catches in Bulo village include tuna using kite fishing gear. Marketing of local catches, decreasing productivity of capture fisheries, and sustainability of fish resources are problems faced by fisheries business actors. The purpose of this service activity is for partners to understand and be able to increase knowledge of sustainable economic businesses for fisheries business actors in Bulo village. The methods used in this service are conducting field surveys and interviews directly with partners, counseling on sustainable economic businesses, and evaluating community service activities. The topics discussed in the community service program included the potential of fishery businesses, steps to start a small-scale fishery business and its management, diversification of processed fishery products and product licensing legality, digital marketing and product branding, microfinance, and access to capital. The results of the evaluation of this community service activity are increasing the knowledge of partners in sustainable economic business.

Purse seines are an efficient fishing gear for catching pelagic fish that live in schools and are found near the surface of the water. Purse seines are considered active because their operation involves blocking, trapping, and restricting the fish's movement, preventing them from escaping. Catching success is influenced by several factors, such as net rotation speed, sinking weights, and the speed of pulling the line, all of which influence the success of purse seine fishing. The continued increase in purse seine operations indicates a continuing increase in the exploitation of fish resources. This condition has led to the issue of overfishing and the increasing scarcity of fishery resources. Overfishing can result in a decrease in catch per unit effort (CPUE), which in turn reduces fishermen's income. Gear selectivity refers to the ability to select or catch fish based on specific species and sizes. Fishing gear with a high level of selectivity tends to prioritize catch quality over quantity. The research was conducted at the Ocean Fisheries Port (PPS) Bungus, from January 13 to May 12, 2025, using a purse seine vessel operating in the waters of West Sumatra (FMA-RI 572). During the research, based on the results obtained, fishing operations were carried out during the day and night. The composition of the catch obtained was a variety of species caught, consisting of bigeye scad (Selar crumenophthalmus), European pilchard (Sardinella pilchardus), Shortfin scad (Decapterus sp.), short mackerel (Rastrelliger sp.), narrow-barred spanish mackerel (Scomberomorus sp.), Largehead hairtail (Trichiurus lepturus), barracuda (Sphyraena barracuda), Kawakawa (Euthynnus affinis), and Squid (Loligo sp.). The total catch during the study was 20,050 kg. The percentage of main catch fish was 33% smaller than the percentage of bycatch of 67%. The main catch was S. crumenopthalmus fish, with a production of 6,645 kg (33%) of the total catch. Thus, it can be concluded that the selectivity of purse seine is relatively low, because bycatch is more dominant due to the large number of fish species caught.

Pelagic fish resources are one of the most important potential resources in Indonesian waters. One small pelagic fish that has high economic value and is currently in high demand is the shortfin scad (Decapterus macrosoma). The production of D. macrosoma in the Nusantara Fishing Port (PPN) Tasikagung is very large. This has led to increased fishing efforts without regard to the existence and sustainability or conservation of the species. This study specifically discusses the bioeconomic analysis of the fishing of D. macrosoma. Therefore, this study aims to make a significant contribution to the development of D. macrosoma fishing in the PPN Tasikagung and surrounding areas. The bioeconomic study of D. macrosoma fishing uses the Gordon Schaefer model, which includes Maximum Sustainable Yield (MSY), Maximum Economic Yield (MEY), Open Access Equilibrium (OAE), utilisation rate and exploitation rate. Several aspects to be assessed in this study include technical aspects of fishing, bioeconomic aspects of fisheries, and utilisation rates. Data collection was carried out through observation, interviews, documentation, and literature studies. The results of the study obtained an average CPUE value for the 2020–2024 period of 29.193 kg per unit. Under MSY conditions, a CMSY value of 15,283,570 kg was obtained, an EMSY value of 601 fishing gear units per year with a profit of IDR 56,181,648,063. Under MEY conditions, the CMEY value was 15,283,338 kg, the EMEY was 599 fishing gear per year, with a total profit of 56,182,508,405. Fishing efforts under OAE conditions yielded a COAE value of 237,371 kg per year and an EOAE of 1,198 fishing gear units per year. The level of exploitation of D. macrosoma resources has reached moderate exploitation with an exploitation rate of 95% and an effort rate of 85%, and the level of exploitation produces an effort of 1.19, which means 0.5 ≤ E < 1= Fully exploited. Fishing efforts are closely monitored to ensure that the D. macrosoma resources at the PPN Tasikagung are not overfished, thereby supporting the sustainability of D. macrosoma fishing efforts in the future and improving the welfare of the fishermen themselves.

Salvelinus malma, belonging to the Salmonidae family, is a critically endangered species in China. To support genetic research and strengthen the protection of wild fish resources, the first chromosome-level reference genome of S. malma was generated through the integrated technologies of PacBio and Hi-C sequencing. The genome assembly has a total length of 2.52 Gb with contigs assigned to 42 chromosomes. A total of 45,385 protein-coding genes were annotated with excellent 98.8% BUSCOs completeness. The chromosome-level genome of S. malma will serve as a valuable resource for functional genomics research and greatly facilitate the ecological conservation in the future.

Sustainable use of fish resources is essential, and decision makers such as the Norwegian Directorate of Fisheries (NDF) must take proactive measures to prevent Illegal, Unreported, and Unregulated (IUU) fishing activities. With access to large volumes of open datasets, machine learning (ML) models can play a key role in automating the detection of hidden patterns indicative of such activities. One valuable dataset is the collection of catch reports, where fishermen record the details of their fishing operations. Previous research has explored the use of ML models to predict expected catch quantities. By comparing these predictions with the actual reported values, potential violations of regulations can be identified. However, to ensure trust in the model’s outputs and to gain deeper insight into the data, this paper applies interpretable Artificial Intelligence (AI) methods and visualization techniques to analyze prediction errors. We investigate feature importance and examine how the most influential features affect the model's output patterns. The results are promising, demonstrating that it is possible to provide transparency in the use of ML models for fisheries data. This approach enables domain experts to better understand, trust, and make informed use of the model's findings in the future.

The Upper Yangtze River National Nature Reserve for Rare and Endemic Fish is a critical sanctuary facing increasing pressure from hydropower development. To assess its current ecological state, we employed environmental DNA (eDNA) metabarcoding on 48 water samples collected from 16 transects in August 2024. Our analysis identified 93 fish species from 3 orders, 13 families, and 67 genera, of which 89 were consistent with historical records. The Cyprinidae family was dominant. The fish community was predominantly characterized by slow-flowing, benthic, omnivorous, and migratory taxa that lay adhesive eggs, with key life-history traits including a sexual maturity age of 1–4 years and a length at first maturity under 20 cm. Spatially, species richness was highest in the Chishui River (64 species), followed by the Minjiang River (61 species). While alpha diversity was largely consistent across most rivers (except the Minjiang), beta diversity analysis revealed significant compositional differences among basins (PERMANOVA, R2 = 0.2747, p = 0.001). Notably, the Chishui River supported not only the highest richness but also a distinct community structure. In summary, this study provides a systematic current status assessment of the reserve’s fish resources, revealing significant spatial heterogeneity, Our findings underscore the potential impacts of dam construction and offer a scientific basis for informing effective conservation strategies.

To understand the status of fish diversity in the middle reaches of the Yangtze River’s Yuanshui River basin during the ten-year fishing ban, this study employed environmental DNA (eDNA) metabarcoding technology. Fish resources were surveyed and diversity analyzed across 38 sampling points within seven river sections of the Yuanshui River basin in September 2023. The results were compared with data obtained using conventional fishing gear methods from four identical sections (Changde, Yuanling, Chenxi, Hongjiang) to explore the application of eDNA technology for fish resource monitoring in the Yangtze River basin and to investigate the similarities and differences in monitoring outcomes between the two methods. The eDNA metabarcoding approach identified a total of 94 fish species, belonging to 10 orders, 17 families, and 57 genera. Cypriniformes was the most abundant order (65 species, 69.15%), and Cyprinidae dominated (54 species, 57.45%) within families. Among the 94 species, 12 were endemic to the Yangtze River basin, 11were key protected wildlife species in Hunan Province, and 3 were non-native species. The predominant ecological traits of the fish assemblage were characterized by lentic-resident habits (56.38%), omnivorous feeding (63.83%), and demersal habitat utilization (45.74%). Diadromous migrants, herbivorous feeders, and lower water column species were relatively scarce. A comparative study in four identical sections of the Yuanshui River utilized environmental DNA (eDNA) metabarcoding and conventional fishing gear to assess fish diversity. Across all sections, eDNA detected a total of 89 fish species while conventional methods detected 93 species, with 62 species co-detected by both approaches. Site-specific comparisons revealed that within the Changde section, eDNA identified 70 species compared to 55 species captured by conventional gear, resulting in 40 shared species. In the Yuanling section, eDNA detected 71 species against 53 species from conventional sampling, yielding 35 co-detected species. The Chenxi section showed eDNA detection of 44 species and conventional gear detection of 38 species, with 20 species found by both methods. Similarly, in the Hongjiang section, eDNA recorded 49 species and conventional methods 47 species, also sharing 20 species. Both the total number of fish species and the number of shared species detected in the Changde and Yuanling sections were significantly higher than those in the Chenxi and Hongjiang sections. Within the same river section, the Shannon diversity index and Pielou evenness index calculated based on the conventional fishing gear data were consistently greater than those derived from the eDNA analysis. This study demonstrates the high credibility of environmental DNA (eDNA) technology for monitoring fish stocks within the Yangtze River Basin. Combining eDNA methods with conventional fishing gear surveys provides a more comprehensive assessment of fish diversity throughout the basin. These findings offer valuable references for evaluating the effectiveness of fishing bans, protecting fish resources, and informing fisheries management strategies in the Yuanshui River and broader Yangtze Basin.

To assess the applicability of environmental DNA (eDNA) technology in monitoring fish diversity in Dongting Lake, located in Hunan Province within the Yangtze River Basin, China, this study combined eDNA metabarcoding with traditional fishing gear to describe the diversity characteristics of the fish community in its habitat. Water samples were collected from 20 representative sites for eDNA analysis, followed by filtration, DNA extraction, and high-throughput sequencing targeting the 12S rDNA region. Concurrently, traditional fishing gear using gill nets and fish traps was conducted at the same locations. The results revealed 82 fish species detected by both methods combined, with eDNA alone identifying 21 species (including rare species encompassing Saurogobio gracilicaudatus and Glyptothorax sinense), while traditional fishing gear detected 27 species. Among the 82 fish species, a total of thirty-four species of fish could be observed in catches from both methods. In terms of α-diversity, eDNA showed higher Chao1, species richness, and ACE indices compared to traditional fishing gear, but lower Shannon and Simpson indices. eDNA was more sensitive to species richness, while traditional fishing gear was better at characterizing community evenness and diversity. β-Diversity analysis showed higher spatial similarity in the fish community structure detected by eDNA, while traditional fishing gear revealed significant differences between the upstream and downstream areas. In summary, eDNA technology has the advantages of non-invasiveness, high sensitivity and broad coverage, effectively serving as a valuable supplementary tool of traditional fishing gear, particularly in monitoring rare species. However, further improvements are needed in terms of species abundance quantification and database dependency. The combination of these two methods provides a more comprehensive scientific basis for fish resource conservation in Dongting Lake.