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Acoustic telemetry is a common tool used in fisheries management to estimate fish space use (i.e., occupancy) from a local habitat scale to entire systems. Numerous analytical models have been developed to estimate different aspects of fish movement from telemetry datasets, yet evaluations of model performance and comparisons among models are limited. Here, we develop a framework to evaluate model estimates of regional occupancy in large and fragmented systems using an acoustic receiver array in Lake Champlain. We simulated the tracks of 100 acoustically tagged fish using a random walk function and created detection events based on receiver positions and distance-based detection probability. Regional occupancy for the simulated data was estimated by six movement models that ranged in analytical complexity, and results were compared to the true distributions for each simulated track to evaluate model error. The six movement models included: (1) a basic residency index using detections alone; (2) a residency index using last-observation-carried-forward; (3) a centers of activity model; (4) linear and non-linear interpolations (i.e., least-cost paths); and (5 and 6) two dynamic Brownian bridge movement models generated using separate packages in R. We developed a model selection process to compare model performance and select the optimal analysis based on simulation error. This process showed significant differences in model performance among the six movement models based on model error. Overall, the model generating least-cost paths using linear and non-linear interpolations consistently provided the most accurate regional occupancy estimates. Based on these simulation results, we applied this model to a case study that evaluated patterns in the regional distribution of stocked lake trout (Salvelinus namaycush) in Lake Champlain, which demonstrated distinct regional occupancy of two stocked lake trout groups. These results demonstrate potential for large variability in interpretation of acoustic telemetry data for describing regional fish distribution dependent on the analytical method used. [ABSTRACT FROM AUTHOR]

Marine sediments are among the largest carbon reservoirs on the planet and play a key role in the global cycling of organic matter. Bottom fisheries are the most widespread anthropogenic physical disturbance to seabed habitats, prompting NGOs and governments to act on regulating mobile bottom-contacting fishing gear. However, the scientific evidence of the effects of bottom trawling on sediment biogeochemistry is highly diverse and presents contrasting results. Here we present a global harmonized dataset of 71 independent studies that assess the effects of demersal fisheries on sedimentological (i.e. grain size, porosity) and biogeochemical (i.e. organic carbon, phytopigments, nutrient fluxes) properties: the Demersal fishery Impacts on Sedimentary Organic Matter (DISOM) database (Paradis, 2023; 10.3929/ethz-b-000634336). We identify considerable gaps, namely in the geographical extension of the data; coverage of environmental predictors (i.e. seasons); fishing descriptors such as the availability of true controls, quantification of fishing effort, and distribution of fishing gear types; and biogeochemical variables that study the remineralization of organic matter. Future studies should address these data gaps to enhance the comprehensiveness of the dataset. With this harmonized database, we aim to allow researchers to explore the effects of demersal fisheries in variable environmental settings to disentangle the effects of this disturbance and provide efficient management strategies. [ABSTRACT FROM AUTHOR]

Emerging fishing activity due to melting ice and poleward species distribution shifts in the rapidly‐warming Arctic Ocean challenges transboundary management and requires proactive governance. A 2021 moratorium on commercial fishing in the Arctic high seas provides a 16‐year runway for improved scientific understanding. Given substantial knowledge gaps, characterizing areas of highest uncertainty is a key first step. Marine ecosystem model ensembles that project future fish distributions could inform management of future Arctic fisheries, but Arctic‐specific variation has not yet been examined for global ensembles. We use the Fisheries and Marine Ecosystem Intercomparison Project ensemble driven by two Earth System Models (ESMs) under two Shared Socioeconomic Pathways (SSP1‐2.6 and SSP5‐8.5) to illustrate the current state of and uncertainty among biomass projections for the Arctic Ocean over the duration of the moratorium. The models generally project biomass increases in more northern Arctic ecosystems and decreases in southern ecosystems, but wide intra‐model variation exceeds projection means in most cases. The two ESMs show opposite trends for the main environmental drivers. Therefore, these projections are currently insufficient to inform policy actions. Investment in sustained monitoring and improving modeling capacity, especially for sea ice dynamics, is urgently needed. Concurrently, it will be necessary to develop frameworks for making precautionary decisions under continued uncertainty. We conclude that researchers should be transparent about uncertainty, presenting these model projections not as a source of scientific "answers," but as bounding for plausible, policy‐relevant questions to assess trade‐offs and mitigate risks. Plain Language Summary: As the Arctic Ocean gets warmer, melting ice is opening up new opportunities for fishing. However, we don't know where fish will go and how they can be managed sustainably. An important first step is to figure out which unknowns we can solve quickly with more research, and what is so uncertain that we will have to make decisions without ideal information. In this paper, we looked at uncertainty in a set of global models that predict how fish populations might shift in the next 10–25 years. Overall, these models show that fish populations might increase in the northern parts of the Arctic while decreasing in the south. But the models make very different predictions, and some disagree on whether fish populations will increase or decrease in certain areas. A major source of uncertainty is how sea ice will change, and how ocean life will respond. Therefore, this is a priority area to invest in long‐term research and better models. Overall, these models are too uncertain to rely on for specific management decisions about Arctic fishing. Instead, scientists and decision makers can use them to shape more informed discussions about potential trade‐offs and risks of future fishing in the Arctic. Key Points: Variation and disagreement in marine ecosystem model projections are too high to be informative for near‐term Arctic fisheries managementInsufficient inclusion and knowledge of sea ice cover and sea ice productivity dynamics are major drivers of uncertaintyResearchers should be transparent about uncertainty and risk; present model projections as the basis for hypotheses and scenario planning [ABSTRACT FROM AUTHOR]

Mercury contamination from gold mining in the Amazon poses significant environmental and health threats to the biome and its local populations. The recent expansion of non-industrial mining areas has severely impacted territories occupied by traditional communities. To address the lack of sampling data in the region and better understand mercury dynamics, this study used the probabilistic model SERAFM to estimate the mercury distribution and bioaccumulation in fish. The analysis covered 8,259 sub-basins across three major Amazonian basins: the Branco, Tapajós and Xingu rivers. The findings revealed increasing downstream mercury levels, with notable accumulations in the main watercourses influenced by methylation processes and mining releases. The projected concentrations showed that an average of 27.47% of the sub-basins might not comply with Brazilian regulations, rising to 52.38% in the Branco and Tapajós river basins separately. The risk assessment of fish consumption based on the projections highlighted high mercury exposure levels among traditional communities, particularly indigenous populations, with an average of 49.79% facing an extremely high risk in the Branco and Tapajós river basins. This study demonstrated SERAFM's capacity to fill information gaps in the Amazon while underscoring the need for enhanced data collection, culturally sensitive interventions and regulatory updates to mitigate mercury contamination in gold mining-affected areas. [ABSTRACT FROM AUTHOR]

Climate warming is one of the facets of anthropogenic global change predicted to increase in the future, its magnitude depending on present-day decisions. The north Atlantic and Arctic Oceans are already undergoing community changes, with warmer-water species expanding northwards, and colder-water species retracting. However, the future extent and implications of these shifts remain unclear. Here, we fitted a joint species distribution model to occurrence data of 107, and biomass data of 61 marine fish species from 16,345 fishery independent trawls sampled between 2004 and 2022 in the northeast Atlantic Ocean, including the Barents Sea. We project overall increases in richness and declines in relative dominance in the community, and generalised increases in species' ranges and biomass across three different future scenarios in 2050 and 2100. The projected decline of capelin and the practical extirpation of polar cod from the system, the two most abundant species in the Barents Sea, drove an overall reduction in fish biomass at Arctic latitudes that is not replaced by expanding species. Furthermore, our projections suggest that Arctic demersal fish will be at high risk of extinction by the end of the century if no climate refugia is available at eastern latitudes. Using a joint species distribution model fitted to 61 species, this study shows that the habitat of Arctic fish might be hugely reduced in the next decades, and potentially eliminated from the Barents Sea. Boreal species are shown to expand their habitat, leading to increased species richness in the area and a diversification of dominance, but this might not increase overall biomass. [ABSTRACT FROM AUTHOR]

While the spatial distribution pattern of fish is increasingly used for toxicological test of chemicals or wastewater, no ideal parameter is available for quantitative assessment of spatial distribution, especially uneven distribution with multiple hotspots. Here, to develop a quantitative assessment parameter for spatial distribution, the zebrafish were exposed to ethanol, pentylenetetrazole (PTZ), paraquat dichloride (paraquat) and wastewater, followed by a behavioral test in a narrow tank. Behavioral data was acquired and analyzed by idTracker and MATLAB. By comparing the effects of all treatments on behavior parameters, we confirmed that the spatial distribution was more easily altered rather than general locomotor parameters, e.g. 0.7–70 mg/L PTZ and 5–20 mg/L paraquat being effective for altering spatial distribution but having little effects on general locomotor parameters. Based on the heatmap, i.e., the cumulative proportion of grids and that of frequency in grids, we calculated the behavioral Gini coefficient (G b) for quantitative assessment of fish spatial distribution. The Gini coefficient ranged from zero to 1, with larger values meaning poorer evenness of spatial distribution. Of note, G b showed smaller coefficient of variations (CV) with 3%-19% between replicate tanks in all treatments than the highest frequency (4%-79%), displaying well robustness. Especially, G b addressed the challenge of the complicated heatmap with multiple hotspots. Overall, the behavioral Gini coefficient we established is an ideal parameter to quantitatively assess spatial distribution of fish shoal, which is expected to be applied in toxicity testing for chemicals and wastewater and automatic quality monitoring for surface water and aquaculture water. [Display omitted] [ABSTRACT FROM AUTHOR]

In an ever-changing environment, detecting shifts in the spatial distribution of marine fish and understanding the relative importance of climate change and biotic factors impacting fish distributions can improve fisheries management. Coincident with the significant increase in Haddock (Melanogrammus aeglefinus) abundance to a historically high levels on Georges Bank (GB) in the last decade, extreme ocean temperature increase was also observed in this region. In this study, the possible seasonal and inter-annual spatial distribution changes of haddock were investigated with >50 years of bottom trawl survey data collected in spring and fall on GB. These data were analyzed using models with spatial, different temporal, and spatio-temporal autocorrelation structures. To characterize the directional changes in haddock spatial distribution, the Center of Gravity (CG) and Area of Occupancy (AO) in each season were estimated from the best model selected by Akaike Information Criteria (AIC). The results showed substantial range expansion/contraction and distribution changes in both spring and fall over time. The relative role of density dependence, age structure, and climate change in affecting haddock distribution was evaluated using a generalized additive model (GAM). It was found that density-dependent habitat selection made the greatest contribution to the variations of AO in both seasons, which is consistent with the MacCall's Basin model theory. Rising ocean temperatures played a major role in shaping a northward distribution shift in fall. GB is the southern edge of haddock distribution in the Northwest Atlantic, continued warming from climate model projections in the next 50 years in this region could make it difficult to define stock boundaries between GB and adjacent Canadian and US domestic management areas. This would subsequently impact fishery management of haddock. [ABSTRACT FROM AUTHOR]

Changes to Earth's climate affect organisms globally; in marine systems, these impacts are seen through warming water temperatures, ocean acidification, hypoxia and frequent marine heatwaves. These effects may lead to the movement of species to more favourable conditions. While climate‐driven movement is well studied at the adult stage, how the early life stages of marine fish will respond to future variability is less clear. Many fish species are constrained by specific spawning locations or phenology. Spawning in certain locations allows for local retention of offspring, while precise timing can facilitate transport of offspring to nursery locations through seasonal circulation patterns. Our research investigates how changing oceans impact the location and timing of spawning of Bering Sea groundfishes over the next century. We used ROMS SST and SSS model output and NOAA survey data in species distribution models to hindcast and project distributions and centre of gravity for eggs and larvae of six groundfish species. Our analyses found that most of our study species exhibit flexible geography. However, the speed and direction of egg and larval movement did not track the speed and direction of their respective thermal niches. Hence, the projected distributional patterns of adult stages may be limited by their early life stages. This response is likely to be mirrored globally by other species with planktonic eggs and larvae. These results indicate that life history considerations are critical for the management of commercially important species, as effects on early life stages are strongly connected to the success or failure of adult populations. [ABSTRACT FROM AUTHOR]

Herein, we present a diverse record of dinoflagellate cysts from the lignite-associated sedimentary succession (belonging to the Akli Formation) at Sonari Lignite Mine, Barmer Basin, Rajasthan State, western India. The dinoflagellate cyst assemblage implies a Danian to Ypresian age for the investigated succession and argues that the deposition of lignitic sequences along India's western margin is not coeval. We also identify two vertebrate (dominantly fish-yielding) units within the studied Akli Formation succession. The Ypresian fish genera (mainly represented by dental remains) include Ginglymostoma, Jaekelotodus, Brachycarcharias, Pycnodus and Myliobatis while the Selandian-Thanetian fish dental remains include Dasyatis. A discontinuous distribution of fish fauna during the early Paleogene (based on the temporal and spatial data) within the lignite-associated sedimentary successions of western and north India allows us to infer the prevalence of separated realms with variably restricted palaeoenvironmental conditions. Overall, the faunal evidence is indicative of dominantly estuarine to shallow marine conditions with enhanced freshwater influence during the Thanetian as compared to the Danian. Our study also argues in favour of the earliest appearance of dinoflagellate cyst Apectodinium in the near-equatorial region of the Tethys Ocean during the early Paleocene. (within Danian). [ABSTRACT FROM AUTHOR]

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

In the Eastern Tropical North Pacific Oxygen Minimum Zone (ETNP‐OMZ), fish larvae undergo development amidst highly variable dissolved oxygen environments. As OMZs expand, understanding the implications of low‐oxygen environments on fish development becomes increasingly relevant for fisheries management and ecosystem modeling. Using horizontal zooplankton tows to track five oxygen levels (oxic [200 μmol/kg], hypoxic [100 μmol/kg] suboxic [10 μmol/kg], anoxic [<1 μmol/kg], and deep [10 μmol/kg at ~ 1000 m depth]), this study analyzed the three‐dimensional distribution of fish larvae and adults across the ETNP‐OMZ. Results revealed a wide midwater anoxic core, extending from Costa Rica to Baja California, that was almost devoid of fish larvae (< 1 larvae/1000 m3). Early larval stages primarily inhabited the oxic and hypoxic levels above the core, while postflexion and transformation stages occurred across a wider oxygen gradient, including the deep level below the anoxic core. Epipelagic species (e.g., Auxis sp.) were predominantly found in the surface oxic level, whereas coastal‐demersal species (e.g., Bregmaceros bathymaster, Ophidion spp.) were prevalent in the hypoxic level above the core. Meso‐bathypelagic species (e.g., Diogenichthys laternatus, Cyclothone spp.) were present throughout the study area, including below the anoxic core as transformation larvae and juveniles. These findings indicate that a vertical expansion of anoxic waters in OMZs could further constrain the habitat of epipelagic species, while also affecting the ontogenic vertical movements of meso‐bathypelagic species. [ABSTRACT FROM AUTHOR]

Objective: Automatic feeders are commonly used in aquaculture, but the feed delivery pattern cannot be adjusted to accommodate a variety of rearing unit sizes. For those few feeders that can be adjusted, their use has been limited because of initial costs, availability, and other issues. This paper describes modification to a commercially available fish feeder (Texas Hunter Products 31.75‐kg [70‐lb] Lake and Pond Directional Fish Feeder) to effectively provide feed to different‐sized ponds. Methods: This feeder has a 14‐m fish feed distribution pattern, making it unusable for smaller ponds. To reduce the distance of fish feed projected from the feeder, a resistor (rheostat) was installed in series with the fan motor. Result: The rheostat reduced the power to the fan motor, thereby decreasing the feed projection distance. In addition, because the rheostat was adjustable, the resistance—and the resulting power to the fan motor—could be easily changed, making it possible for the same feeder to be used in different‐sized ponds while using approximately the same amount of power from the battery and solar panels. Conclusion: This modification was inexpensive and relatively easy to perform. The feeders reliably dispensed feed in a number of small ponds during an 8‐month evaluation period. Impact statementThis paper describes an inexpensive and relatively easy to perform modification to a commercial fish feeder so that it can effectively dispense feed in small rearing ponds. [ABSTRACT FROM AUTHOR]

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

Changes in fish habitat induced by dam construction in the downstream river have been well documented in an increasing body of literature. Fish habitats in the backwater zone of dams have undergone dramatic changes, which have still remained poorly understood. This study aims to provide a more complete understanding of fish habitat distribution and clarify fish habitat utilization patterns in the upstream dam in order to adopt effective remediation activities. This study was conducted in the Three Gorges Dam (TGD) as it is the world's largest installed capacity hydropower station, with a backwater zone length of about 660 km. Four major Chinese carp (FMCC) were selected as target fish species, and fish habitat distribution upstream of TGD was assessed by integrating the swimming ability and environmental preference of different fish species into their critical life stages. Assessment results at different life stages of the target fish species showed that June was a critical period for spawning activities FMCC in the fluctuating backwater zone of TGD. The riverbank was an important feeding habitat for FMCC, and the high‐velocity flow in the centre of the channel exceeded the limits of the swimming ability of target fish. The fish habitat distribution in the fluctuating backwater zone of TGD was heavily affected by runoff from April to September and by dam operation from October to March of the next year. This work provide valuable information about river conservation and management in the upstream of TGD. [ABSTRACT FROM AUTHOR]

Small-scale fisheries exhibit unique, diverse, and varied characteristics in each region. These distinctive traits render small-scale fisheries challenging to regulate centrally. This research aims to compare the characteristics of land-based and island-based small-scale fisheries in Southeast Sulawesi Province. Data were collected through structured interviews involving 445 respondents from two distinct areas: North Konawe, representing land-based fisheries, and Konawe Islands, representing island-based fisheries. Both qualitative (questionnaire data) and quantitative analyses were conducted using R software. Proportion data were tested using the R ggstatsplot package, while word cloud analysis utilized the R wordcloud package. The analysis of fishing ground distribution hotspots was performed using QGIS software version 3.30. The research findings demonstrate differences across various aspects, including education levels, boat sizes, fishing frequency, monthly income, and types of captured fish. Furthermore, the study highlights that island-based small-scale fisheries hold a higher income potential compared to their landbased counterparts. These differing characteristics serve as essential considerations in developing policies that support sustainable management of small-scale fisheries based on the needs of local communities. [ABSTRACT FROM AUTHOR]

This study investigates the behavior of chubs (Squalius cephalus) of mid-body length (9.7–15.6 cm) with respect to turbulent flow conditions in a pool representing an experimental vertical slot fishway. Velocity and turbulence were characterized using PIV data. The influence of turbulent flow on fish behavior was assessed through the number of successful fish passage attempts, the associated passage times, and the spatial distribution of fish in the pool. Turbulence conditions were modified by the addition of one or three vertical rigid cylinders inside the pool. The results show that these adaptations may facilitate the passage of chubs. Results provide valuable insights and information to understand the relationship between fish behavior and hydraulic conditions, especially in the context of improving the design of fishways. [ABSTRACT FROM AUTHOR]

Ecological processes that are behind distributions of species that inhabit isolated localities, complex disjunct distributions, remain poorly understood. Traditionally, vicariance and dispersion have been proposed as explanatory mechanisms that drive such distributions. However, to date, our understanding of the ecological processes driving evolution of ecological niches associated with disjunct distributions remains rudimentary.Here, we propose a framework to deconstruct drivers of such distribution using World's most widespread freshwater fish Galaxias maculatus as a model and integrating marine and freshwater environments where its life cycle may occur. Specifically, we assessed ecological and historical factors (Gondwanan vicariance, marine dispersion) and potential dispersion (niche‐tracking) that explain its distribution in the Southern Hemisphere.Estimated distribution was consistent with previously reported distribution and mainly driven by temperature and topography in freshwater environments and by primary productivity and nitrate in marine environments. Niche dynamics of G. maculatus provided evidence of synergy between vicariance and marine dispersion as explanatory mechanisms of its disjunct distribution, suggesting that its ecological niche was conserved since approximately 30 Ma ago.This integrated assessment of ecological niche in marine and freshwater environments serves as a generic framework that may be applied to understand processes underpinning complex distributions of diadromous species. [ABSTRACT FROM AUTHOR]

Machine learning occupies a central position in the modeling of fish distribution patterns. The augmentation of explanatory variables in fish habitat through many kinds of observational methodologies necessitates the discernment of an optimal combination of these variables for fish distribution modeling. We proposed a feature selection technique, recursive feature elimination with cross-validation (RFECV), to determine optimal variables combinations for yellowfin tuna distribution in the Pacific Ocean. Four tree-based models, random forest, eXtreme Gradient Boosting, Light Gradient Boosting Machine, and categorical boosting driven by RFECV, were developed using comprehensive fisheries and biotic/abiotic data. Habitat variables including sea temperature, dissolved oxygen concentration, chlorophyll-a concentration, sea salinity, and sea surface height were identified as significant features by all models. The models were trained using the corresponding selected variables, and these trained models were employed to predict the spatiotemporal distribution of yellowfin tuna from 1995 to 2019. The results obtained could inform useful knowledge for the sustainable exploitation of yellowfin tuna in the Pacific Ocean and furnish a benchmark of feature selection for machine-learning-based distribution modeling of other pelagic species. [ABSTRACT FROM AUTHOR]

The management and conservation of faunas at regional scales depend on current data on species diversity and distribution. Relative to the ichthyofauna of West Virginia, few studies have recently documented the richness and distribution of fishes in the state, with even the most comprehensive publications rarely discussing either the conservation status of individual fishes or historical sportfish stockings. In this paper, we review the state's historic sportfish stockings. We also clarify inconsistent published data and present new information for several species, delete 3 species from the West Virginia ichthyofaunal list, and add 35 species representing extant or extirpated populations. Lastly, we provide a checklist of 195 species by major drainage of West Virginia's fishes, including their origin (i.e., native or introduced). [ABSTRACT FROM AUTHOR]

Artisanal fishing is an important subsistence practice in freshwater habitats worldwide, but overexploitation threatens the conservation of several nontarget species including crocodylians. We investigated the effects of artisanal fishing on the distribution of a population of broad‐snouted caiman (Caiman latirostris) inhabiting the Tapacurá reservoir, within the highly altered and threatened Atlantic Forest biome.We conducted spotlight surveys to detect caimans and gillnets deployed in the reservoir from April 2015 to June 2022. We evaluated temporal differences in gillnet encounter rates and the relationship between caimans and gillnet distribution.Gillnet encounter rates remained consistent year‐round, while caiman encounter rates were highest near gillnets, especially in the river channel and in forested margins. Caimans are opportunistic predators attracted by tangled fish in gillnets and likely prefer habitats with increased fish abundance.Future research should continue monitoring the interaction between caimans and fishing and include local communities in conservation efforts. [ABSTRACT FROM AUTHOR]

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

Day and nighttime autumn fish abundance and biomass were studied in the pelagic and littoral zones of Lake Sauka in Latvia. Both pelagic methods (hydroacoustics and trawling) revealed significantly higher fish abundance and biomass during the day than at night, especially in deeper zones (below 3 m). Roach (Rutilus rutilus) and Eurasian perch (Perca fluviatilis) dominated the trawl catches during the day, while roach and ruffe dominated at night. Fish smaller than 14 cm strongly dominated in both the trawl catches and hydroacoustic observations. Our hydroacoustic sampling found inhomogeneous pelagic distributions of fish aggregated in big shoals during the day. In the littoral zone, which was sampled by beach seining, both the abundance and biomass were significantly higher at night than during the day. Roach, bleak, and European perch usually dominated in beach seine catches during the day and at night. The daytime pelagic biomass found by hydroacoustics was 62 kg/ha and it decreased to approximately 11 kg/ha at night. The littoral biomass found by beach seining was diurnally opposite, 4 kg/ha during the day and 37 kg/ha at night. It is obvious that diurnal horizontal migrations between pelagic and littoral zones, and shoaling behavior during the daytime are common patterns in the shallow Lake Sauka during the autumn. The study of the spatial distribution of fish is extremely important for the establishment of an appropriate monitoring plan for the purposes of the Water Framework Directive with regard to the morphometry of the lake, the geographical location, and the sampling period of the year. This study also shows that the combination of completely non‐invasive hydroacoustic and other methods that are invasive (trawls, beach seines) but not as destructive as gillnets, which are normally used for scientific fish monitoring in Europe, could be a future way forward for fish monitoring. [ABSTRACT FROM AUTHOR]

Muncar is the largest fish landing which produced Bali Sardinella (Sardinella lemuru) in Banyuwangi. Sardinella was caught by purse seine. During fishing by purse seine, target species was Bali Sardinella while another catch was called bycatch. Some researchers indicated that bycatch was one factor affecting fish stock depletion. The aim of this research was to investigate catch composition and size distribution of dominant fish caught by purse seine. Result of observation at 10 fishing trip indicated that catch of purse seine was dominated by Bali Sardinella (Sardinella lemuru) which total account of 3.360 fishes or 77,83 % as a target catch, and the bycatch is layang (Decapterus ruselli) about 596 fishes or 13,77%, and slengseng (Scomber australasicus) about 363 fishes or 8,40%. The size of lemuru who caught in this research is between 12-21 cm. Dominant caught at size 14-15 cm about 2.032 fishes (46,97%), and a least caught at >18 cm about seven fishes (0,16%). The size of layang who caught in this research is between 13-25 cm. Dominant caught at size 19-20,5 cm about 255 fishes (5,20%), and a least caught at size 23,5-25 cm about one fishes (0,02%). The size of slengseng who caught in this research is between 13-28 cm. Dominant caught at size 23-25 cm about 143 fishes (3,30%) and least caught at size 27-28 cm only two fishes (0,04%). [ABSTRACT FROM AUTHOR]

The field of fish microbiome research has rapidly been advancing, primarily focusing on farmed or laboratory fish species rather than natural or marine fish populations. This study sought to reveal the distinctive gut bacteriome composition and diversity within the anadromous fish species Tenualosa ilisha (hilsa), which holds the status of being the national fish of Bangladesh. We conducted an analysis on 15 gut samples obtained from 15 individual hilsa fishes collected from three primary habitats (e.g., freshwater = 5, brackish water = 5 and marine water = 5) in Bangladesh. The analysis utilized metagenomics based on 16S rRNA gene sequencing targeting the V3-V4 regions. Our comprehensive identification revealed a total of 258 operational taxonomic units (OTUs). The observed OTUs were represented by six phyla, nine classes, 19 orders, 26 families and 40 genera of bacteria. Our analysis unveiled considerable taxonomic differences among the habitats (freshwater, brackish water, and marine water) of hilsa fishes, as denoted by a higher level of shared microbiota (p = 0.007, Kruskal-Wallis test). Among the identified genera in the gut of hilsa fishes, including Vagococcus, Morganella, Enterobacter, Plesiomonas, Shigella, Clostridium, Klebsiella, Serratia, Aeromonas, Macrococcus, Staphylococcus, Proteus, and Hafnia, several are recognized as fish probiotics. Importantly, some bacterial genera such as Sinobaca, Synechococcus, Gemmata, Serinicoccus, Saccharopolyspora, and Paulinella identified in the gut of hilsa identified in this study have not been reported in any aquatic or marine fish species. Significantly, we observed that 67.50% (27/40) of bacterial genera were found to be common among hilsa fishes across all three habitats. Our findings offer compelling evidence for the presence of both exclusive and communal bacteriomes within the gut of hilsa fishes, exhibiting potential probiotic properties. These observations could be crucial for guiding future microbiome investigations in this economically significant fish species. [ABSTRACT FROM AUTHOR]

This paper reports the presence of the common dolphinfish, Coryphaena hippurus, in Argentinian waters for the first time, with a specimen collected by experienced sport fishermen near Mar del Plata (38°S). This finding also represents the first record of a species from the Coryphaenidae family in Argentinian waters. The collection of these specimens coincided with sightings of other rarely-seen pelagic and oceanic fish species during the same period, providing further evidence supporting the influx of subtropical fish species from warmer Brazilian waters. These observations highlight the need for continued monitoring of fish populations and their distribution and the ecological dynamics within the region. [ABSTRACT FROM AUTHOR]

Environmental DNA (eDNA) is an effective tool for describing fish biodiversity in lotic environments, but the downstream transport of eDNA released by organisms makes it difficult to interpret species detection at the local scale. In addition to biophysical degradation and exchanges at the water–sediment interface, hydrological conditions control the transport distance. A new eDNA transport model described in this paper considers downstream retention and degradation processes in combination with hydraulic conditions and assumes that the sedimentation rate of very fine particles is a correct estimate of the eDNA deposition rate. Based on meta‐analyses of available studies, the particle size distribution of fish eDNA (PSD), the relationship between the sedimentation rate and the size of very fine particles in suspension, and the influence of temperature on the degradation rate of fish eDNA were successively modelled. After combining the results in a mechanistic‐based model, the eDNA uptake distances (distance required to retain 63.21% of the eDNA particles in the riverbed) observed in a compilation of previous experimental studies were correctly simulated. eDNA degradation is negligible at low flow and temperature but has a comparable influence to background transfer when hydraulic conditions allow a long uptake distance. The wide prediction intervals associated with the simulations reflect the complexity of the processes acting on eDNA after shedding. This model can be useful for estimating eDNA detection distance downstream from a source point and discussing the possibility of false positive detection in eDNA samples, as shown in an example. [ABSTRACT FROM AUTHOR]

The study reports on the capture of a new-born specimen of shortfin mako shark Isurus oxyrinchus Rafinesque, 1810 off Karantina islet coast, Urla, Izmir (north Aegean Sea). This specimen measured 761 mm in total length and weighed 2900 g. The historical and recent captures of the species in the area shows the presence of new-born, juvenile and adult males and females. The distribution of these specimens suggests the potential occurrence of a nursery ground in the same area. To preserve the extirpation of the species throughout the area where it finds favourable environmental parameters to live, a management plan should be conducted to ensure the establishment of a viable population in the Turkish marine waters. [ABSTRACT FROM AUTHOR]

Few studies have been done on the interspecific relationship between fishes species, an important part of mangrove wetlands. In 2022-2023, a sampling survey was conducted on the mangrove tidal gully fish in the estuary area of Haishan Town, Raoping County, Guangdong Province in spring, summer, autumn and winter, and the composition of fish species in the mangrove wetland was studied. The aim of this study was tried to elucidate the response relationship between the distribution and interspecific relationships of wetland fish and the effects of environmental factors by calculating the spatiotemporal niche width and interspecific overlap values. The results showed that a total of 14 species belonging to 12 families and 6 orders were identified, including 6 dominant species (IRI≥500), 3 common species (500>IRI≥100), 2 rare species (100>IRI≥10) and 3 occasional species (IRI<10). The spatiotemporal niche width of the fish in mangrove tidal gullies ranged from 0.000 to 2.428, with a large variation range, including 1 species of wide niche species (Bij≥2.0) (Oreochromis niloticus), 2 species of medium niche species (1.0≤Bij<2.0)(Odontamblyopus rubicundus and Bostrichthys sinensis), and the remaining 11 species narrow niche species (00.6) were highly significant overlapped (0.6), accounting for 47% of the total logs, and 21 pairs (0.3< overlap value <0.6) were significant overlapped, accounting for 23% of the total logs, and the two pairs accounted for 70% of the total logs. The highest spatiotemporal niche overlap values were found in Siganus oramin and Periophthalmus cantnensis (up to 0.956), while the lowest non-overlap values were included in O. niloticus and Platycephalus indicus, B. sinensis and P. indicus, and Paraplagusia bilineata and P. indicus, all with the value of 0. BIOENV analysis showed that the most suitable combinations of environmental factors for fish abundance in the study area were water temperature, salinity, pH and chlorophyll a content, which the correlation coefficient is 0.475, and the RELATE test results were significant (R=0.461, P<0.05), indicating that these four environmental factors were important in affecting fish distribution. In general, the spatiotemporal niche of fish in the mangrove wetland of Raoping Haishan town was dominated by narrow niche species, and the spatiotemporal niche overlap between different fish species was significant and meaningful. The water temperature, salinity, pH and chlorophyll a content of the water body were important environmental factors affecting the distribution of fish in the wetland in the forest area. [ABSTRACT FROM AUTHOR]

With the global population growth and increasing demand for high-quality protein, aquaculture has experienced rapid development. Fish culture management and feed supply are crucial components of aquaculture. Traditional baiting management relies on experiential judgment and regular observation, which often leads to inefficient baiting practices and wastage. To address these issues, intelligent bait casting decisions have emerged. Leveraging advanced artificial intelligence algorithms, intelligent bait casting decisions can overcome most drawbacks of traditional bait management and enhance breeding efficiency. However, most of the current intelligent baiting decisions are focused on using methods such as image processing and target detection to identify different feeding actions and patterns. These methods do not discuss based on video streams and do not consider the changes in fish behavior during the baiting process. Therefore, we proposed a real-time analysis method based on the density distribution of fish feeding behavior (FishFeed). Firstly, this method upgrades the input mechanism, not only handling static images but also capable of real-time video stream analysis. Secondly, by evaluating the fish school density distribution through a new intelligent baiting strategy, this method can monitor the feeding behavior of fish school during the baiting process in real time. Finally, we constructed a dataset for fish school density analysis (DlouFishDensity) that includes a wealth of video and image frames, providing a valuable resource for research. Experimental results indicate that our algorithm outperforms MCNN, improving MAE by 1.63 and 1.35, MSE by 1.92 and 1.58, and reducing prediction time by 2.56 seconds on the same dataset. By implementing real-time analysis of fish feeding behavior density distribution, our method offers a more efficient and effective approach to baiting management in aquaculture, contributing to improved breeding efficiency and resource utilization. [ABSTRACT FROM AUTHOR]

The decreased color intensity of Nemo is related to the amount of carotenoid concentration in the xanthophore of Nemo's skin. Therefore, efforts are needed to maintain stable carotenoid production. Tomato is one of the most abundant carotenoid producers. The utilization of carotenoids can maintain the morphological color of aquatic organisms. This study aimed to analyze the effect of carotenoid compounds on total carotenoid content, the size, and distribution of xanthophores on Nemo skin. A total of 60 Nemo with an average initial weight of 0.84±0.14 g and an average length of 2.95±0.08 cm. The research was conducted using a completely randomized design (CRD), consisting of four carotenoid concentrations in addition to fish pellet, 0%, 0.5%, 1%, and 1.5% with three replications. The results showed that the optimum dose of carotenoid compounds in increasing the total carotenoid content in nemo fish skin is 1.5%. Carotenoids added to the fish feed affected the distribution and maturity of xanthophore. However, it did not affect the size of the xanthophore. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) are increasingly relied upon to preserve biodiversity and ensure fisheries sustainability. Although recent analyses have shown that MPAs can provide overall biodiversity benefits even when they only redistribute fishing effort, these did not account for refuges outside of fishing grounds for non‐target species. It has been argued that such refuges could render MPAs obsolete where their chief benefit is to ensure species persistence.Here, we modelled the outcomes associated with placing MPAs within a seascape where non‐target species' ranges can extend beyond fishing grounds.In scenarios with no explicit fishing‐induced habitat damage, we found that MPAs provided a net biodiversity benefit so long as there was at least an approximately 60% overlap between fishing grounds and non‐target species' ranges. In scenarios with explicit fishing‐induced habitat damage for non‐target species, we found that MPAs instead benefitted biodiversity at all overlaps, but that this was reduced if target species' abundances also declined with damage.Additionally, we identified counterintuitive mechanisms by which MPAs could either help or harm the same species depending on their location by changing fishing effort distribution patterns. However, MPAs did always increase the total fishing effort required to reach a catch target.Policy implications: Our results showed that MPAs could still deliver biodiversity benefits in otherwise well‐regulated fisheries when species' ranges and fishing grounds did not fully overlap, and particularly when sensitive species and habitats were present. Well‐placed MPAs should thus be considered in such settings. However, MPAs were also less likely to be useful when range overlaps were low and always resulted in higher fishing effort to maintain the same catches. [ABSTRACT FROM AUTHOR]

Objective: Fish movements and distributions throughout an ecosystem are important for understanding ecological interactions, conservation, and management. Coarse woody habitat (CWH) additions are a popular habitat enhancement tool that can influence movements and distributions of fishes; however, behavioral responses in relation to CWH additions are understudied. The objectives of our study were to test for changes in habitat use and behavioral responses of Muskellunge Esox masquinongy, Smallmouth Bass Micropterus dolomieu, and Walleye Sander vitreus to CWH additions in a small inland northern lake over 3 years and to evaluate two common forms of fish tracking to estimate daily movement of these fishes. Methods: We used passive integrated transponder tag data collected continuously at 10 littoral sites and radiotelemetry data collected biweekly during the summer-fall months prior (2017) and following (2018-2019) CWH addition to examine movement behaviors and estimate daily probability of movement for the three species among lake habitats using multistate models. Result: Walleye were the most likely to remain near CWH, followed by Smallmouth Bass and Muskellunge. All species were more likely to move away from the modified and unmodified littoral zones and were more likely to remain in the offshore zone. Increased movement of fish may be in response to CWH creating a refuge for forage fish and subsequent increases in prey search times. Conclusion: Our results suggest that CWH additions may alter established species-specific annual movements, distributions, and habitat use to differing degrees in ecosystems, as our results differ from other CWH studies. Methodologically, radio-tagging was most effective for offshore tracking but most labor intensive. Novel passive integrated transponder arrays (less labor intensive once installed) worked well to monitor movement between habitat types in shallow littoral areas. Long-term monitoring of behavioral changes will be essential to assessing the stability changes caused by these habitat alterations. [ABSTRACT FROM AUTHOR]

Biodiversity loss in river ecosystems is much faster and more severe than in terrestrial systems, and spatial conservation and restoration plans are needed to halt this erosion. Reliable and highly resolved data on the state of and change in biodiversity and species distributions are critical for effective measures. However, high‐resolution maps of fish distribution remain limited for large riverine systems. Coupling data from global satellite sensors with broad‐scale environmental DNA (eDNA) and machine learning could enable rapid and precise mapping of the distribution of river organisms. Here, we investigated the potential for combining these methods using a fish eDNA dataset from 110 sites sampled along the full length of the Rhone River in Switzerland and France. Using Sentinel 2 and Landsat 8 images, we generated a set of ecological variables describing both the aquatic and the terrestrial habitats surrounding the river corridor. We combined these variables with eDNA‐based presence and absence data on 29 fish species and used three machine‐learning models to assess environmental suitability for these species. Most models showed good performance, indicating that ecological variables derived from remote sensing can approximate the ecological determinants of fish species distributions, but water‐derived variables had stronger associations than the terrestrial variables surrounding the river. The species range mapping indicated a significant transition in the species occupancy along the Rhone, from its source in the Swiss Alps to outlet into the Mediterranean Sea in southern France. Our study demonstrates the feasibility of combining remote sensing and eDNA to map species distributions in a large river. This method can be expanded to any large river to support conservation schemes. [ABSTRACT FROM AUTHOR]

Predicting fishing effort distribution is crucial for guiding fisheries management in developing effective strategies and protecting marine ecosystems. This task requires a deep understanding of how various hydrological factors, such as water temperature, surface height, salinity, and currents influence fishing activities. However, there are significant challenges in designing the prediction model. Firstly, how hydrological factors affect fishing effort distributions remains unquantified. Secondly, the prediction model must effectively integrate the spatial and temporal dynamics of fishing behaviors, a task that shows analytical difficulties. In this study, we first quantify the correlation between hydrological factor fields and fishing effort distributions through spatiotemporal analysis. Building on the insights from this analysis, we develop a deep-learning model designed to forecast the daily distribution of fishing effort for the upcoming week. The proposed model incorporates residual networks to extract features from both the fishing effort distribution and the hydrological factor fields, thus addressing the spatial limits of fishing activity. It also employs Long Short-Term Memory (LSTM) networks to manage the temporal dynamics of fishing activity. Furthermore, an attention mechanism is included to capture the importance of various hydrological factors. We apply the approach to the VMS dataset from 1,899 trawling fishing vessels in the East China Sea from September 2015 to May 2017. The dataset from September 2015 to May 2016 is used for correlation analysis and training the prediction model, while the dataset from September 2016 to May 2017 is employed to evaluate the prediction accuracy. The prediction error ratio for each day of the upcoming week range is only 5.6% across all weeks from September 2016 to May 2017. HyFish, notable for its low prediction error ratio, will serve as a versatile tool in fisheries management for developing sustainable practices and in fisheries research for providing quantitative insights into fishing resource dynamics and assessing ecological risks related to fishing activities. [ABSTRACT FROM AUTHOR]

In summer, the survival zones of cold‐water species are predicted to narrow by both increasing water temperatures from the surface and by expanding hypoxic zones from the lake bottom. To examine how the abundance of cold‐water fishes changes along environmental gradients, we assessed the vertical environmental DNA (eDNA) distributions of three salmonid species which may have different water temperature tolerances during both stratification and turnover periods using quantitative PCR (qPCR). In addition, we examined on the vertical distribution of diverse fish fauna using an eDNA metabarcoding assay. The results suggested that the kokanee salmon (Oncorhynchus nerka) eDNA were abundant in deep, cold waters. On the other hand, rainbow trout (O. mykiss) eDNA were distributed uniformly throughout the water column, suggesting that they may have high water‐temperature tolerance compared with kokanee salmon. The eDNA concentrations of masu salmon (O. masou) were below the detection limit (i.e., <10 copies μL−1) at all stations and depths and hence could not be quantified during stratification. Together with the finding that the eDNA distributions of other prey fish species were also constrained vertically in species‐specific ways, our results suggest that climate change will result in substantial changes in the vertical distributions of lake fish species and thus affect their populations and interactions. [ABSTRACT FROM AUTHOR]

Fish distribution in the lagoon complex of Lake Nokoué and Porto-Novo Lagoon is poorly documented. The lagoon complex is of particular interest because of its contribution to the local supply of animal protein. The fish communities in the complex were studied monthly between January and December 2015 at six sampling sites using two sets of gillnets with varying mesh sizes. The study applied a non-linear self-organizing map (SOM) method to classify the sampling sites based on the composition of fish assemblages, and an index of indicator value (IndVal) was calculated for each species identified. In total, 58 species from 49 genera and 34 families were cataloged with 45 species observed in Lake Nokoué and 48 in the Porto-Novo Lagoon. Notably, 35 species were common to both water bodies. The analysis revealed a dominance of occasional continental (20.7%) and strict estuarine species (20.7%). The SOM analysis suggested a tripartite structure of the fish communities, largely influenced by the geographical positioning of the sampling sites. The IndVal method identified 28 indicator species in the typical assemblages delineated by the SOM approach. The study highlights the importance of these indicator species for the conservation efforts aimed at sustaining the ichthyofauna of the lagoon complex. [ABSTRACT FROM AUTHOR]

Ample evidence has indicated shifts in distribution of fish populations in response to environmental stress. However, most studies focused at the whole population scale. This neglects the spatial dynamics between groups of different body size (body size groups), that fundamentally shapes the spatial structure of a population. Here, we explored the mechanisms that modulate spatial dynamics of body size groups, and applied our analyses to three North Sea fish populations which experienced severe declines in biomass from 1977 to 2019: Atlantic cod Gadus morhua, haddock Melanogrammus aeglefinus and whiting Merlangius merlangius. All three populations exhibited strong declines in the overlapped area between body size groups in winter over 43 years, yet their mechanisms differed. These declines were either due to 1) different magnitudes of contraction of the distribution area of body size groups; and/or 2) different speeds and directions of spatial shift among various body size groups, both increasing spatial segregation within populations. These patterns were either associated with ocean warming, and/or declining population biomass, and such associations often varied according to distinct body size groups. Increasing spatial segregation between size groups of a population likely hampers life‐cycle connectivity and stability to local perturbations. Our analytical approach provides a powerful tool for identifying vulnerable populations under environmental stress and can be generalized to study a variety of size/age structured populations at various ecosystem types. [ABSTRACT FROM AUTHOR]

Ecological models are used to understand where fishing vessels operate, improving fisheries management success. The ideal free distribution (IFD) predicts equalization of catch across locations in response to distributions of fish and competing vessels. We applied the IFD as a null model to investigate the movement and catch per vessel (CPUE) of the sockeye salmon drift gillnet fleet in Bristol Bay, AK, from 1980 to 2019. The IFD prediction of equal CPUE across areas was not supported, so we explored violations of two assumptions of the theory. We categorized each vessel according to its mobility, highlighting the "free to move" assumption, and found that when we removed nonmobile vessels, some districts had fewer vessels than predicted from their high CPUE. We examined the "equal competitive ability" assumption by calculating the average CPUE, relative to success of other vessels. The underutilization of profitable districts persisted. Overall, the fleet underused high CPUE areas when considering differences in mobility and relative fishing success, indicating that unmeasured safety concerns, travel costs, knowledge of fishing grounds, or other factors could be preventing an IFD. [ABSTRACT FROM AUTHOR]

East Lake in Wuhan, China, harbors a high number of freshwater fish species of great conservation value, concurrently serving as vital resources for local livelihoods. However, the ecosystem is threatened by an array of anthropogenic activities, thus requiring consistent monitoring of the local fish community to enable more efficacious conservation management. In place of conventional surveying methods, we undertook the first analysis of the fish distribution within East Lake via metabarcoding of environmental DNA (eDNA). The accuracy and efficacy of eDNA metabarcoding rely heavily upon selecting an appropriate primer set for PCR amplification. Given the varying environmental conditions and taxonomic diversity across distinct study systems, it remains a challenge to propose an optimal genetic marker for universal use. Thus, it becomes necessary to select PCR primers suitable for the composition of fish in the East Lake. Here, we evaluated the performance of two primer sets, Mifish-U and Metafish, designed to amplify 12S rRNA barcoding genes in fishes. Our results detected a total of 116 taxonomic units and 51 fish species, with beta diversity analysis indicating significant differences in community structure diversity between the six sampling locations encompassing East Lake. While it was difficult to accurately compare the species-level discriminatory power and amplification bias of the two primers, Mifish outperformed Metafish in terms of taxonomic specificity for fish taxa and reproducibility. These findings will assist with primer selection for eDNA-based fish monitoring and biodiversity conservation in the East Lake and other freshwater ecosystems. [ABSTRACT FROM AUTHOR]

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

There is no information on the species associated with the mesophotic reefs of Banderas Bay, located in the central Mexican Pacific. This study analysed the reef fish assemblage from three depths (50, 60 and 70 m) in three sampling sites of the southern submarine canyon of the Bay: Los Arcos, Bajo de Emirio and Majahuitas. Several analyses were performed to test the hypothesis that there are important differences in fish abundance and species composition between sites and depths. Twenty-two species of bony fishes grouped in 14 families were recorded. PERMANOVA results showed that there were no significant differences in fish diversity parameters between sites, indicating a certain uniformity in their distribution. However, nine species were exclusive to one site and depth (five singleton species with only one individual recorded and four unique species recorded only once). On the other hand, there were significant differences between depths, mainly between 50 and 70 m. Diversity decreases with depth and species composition changes. SIMPER, Shade Plot and NMDS analysis show the most representative species at each depth, with at least half of the species (11) recorded only at 50 m and four species at the deeper levels (60 - 70 m). The observed assemblage includes several of the most caught species in the shallow water artisanal fishery, which is the most traditional and common type of fishery in the Bay. In addition, the Pomacanthus zonipectus (Cortés angelfish) is of particular interest, as it has a special protection status in the official Mexican standard (NOM-059-SEMARNAT, 2010) due to its use as an ornamental species in aquaria. We hypothesised that the mesophotic zone may serve as a refuge for these fishes, so we propose that the information obtained is an important basis for new research aimed at the sustainable management of fisheries in the area. [ABSTRACT FROM AUTHOR]

Introduction: Biodiversity loss poses a significant environmental challenge, particularly in aquatic ecosystems. The advent of environmental DNA (eDNA) sampling technology offers a promising tool for monitoring biological communities with purported high efficiency. Yet, its efficacy compared to traditional sampling methods remains underexplored, especially in fish diversity research. Methods: This study conducted a comparative analysis of fish diversity and distribution across 29 sampling points within the rivers of the Changqing Nature Reserve, Central China, employing both eDNA techniques and traditional sampling methods. Results: A total of 46 unique fish species were identified through this comprehensive approach. eDNA sampling detected 34 species, surpassing the 22 species identified by traditional methods. Interestingly, 10 species were detected by both methods, while traditional methods exclusively identified 12 species not detected by eDNA, and eDNA uniquely identified an additional 24 species. Despite eDNA's broader species detection range, traditional sampling methods typically yielded higher Shannon diversity index values. Both β-diversity indices (Bray-Curtis and Jaccard) and multivariate analyses (NMDS and PCoA) were applied, revealing no significant statistical differences in biodiversity measurement between the two sampling methods. Discussion: The findings suggest that while eDNA sampling excels in identifying a wider range of species, it does not significantly outperform traditional methods in overall biodiversity assessment. By integrating both methodologies, this study demonstrates a more comprehensive and precise assessment of riverine biodiversity, underscoring the benefits of a synergistic approach for enhancing species detection and understanding distribution patterns. The combined methodology notably improves alpha diversity evaluations, particularly regarding Shannon diversity and Berger-Parker dominance. This integrated approach advocates for the amalgamation of data from both eDNA and conventional methods, fostering a robust and accurate biodiversity appraisal. [ABSTRACT FROM AUTHOR]

Hilsa (Tenualosa ilisha) is a premium table fish in the eastern and some parts of the north-eastern region of India, especially for the Bengali community, contributing uniquely to the societal and economic significance of artisanal fisheries of the country. The major distribution of the fish species in India lies in the Bhagirathi-Hooghly component of the Ganga River system. The aim of the study was to examine if traditional Hilsa fisheries in India are sustainable as the livelihood of artisanal fishers in light of the socio-economic conditions of Hilsa fishers in West Bengal. Structured socio-economic surveys were conducted with 402 fishermen from the upper stretch of river Hooghly to its lower stretch (300 km) in West Bengal during 2020-2021. The average monthly income of the Hilsa fishers in the lower stretch of river Hooghly (Godakhali) (₹25,000-30,000/USD 301-361) was higher than that in the upper stretch at Farakka (₹10,000-15,000/USD 120-180). However, fish species other than Hilsa are generating significantly higher returns for 56% of fishers in the Hooghly district; 40% of Hilsa fishers in South 24 Parganas and Murshidabad (Farakka) districts are engaged in non-fishery activities for livelihood. There are significant differences between Hilsa fishers with other fisheries as secondary occupations and those with non-fishery activities as secondary occupations in terms of socio-economic characteristics. These imply that Hilsa fisheries are profitable as a continued traditional livelihood, but it alone is not sufficient enough to support the livelihood of the artisanal fishers. This indicates the threatened economic sustainability of the Hilsa fisheries sector at present. Considering the high market demand for Hilsa in the eastern and north-eastern regions of India and the market complexities, more significant investments need to be channeled into the Hilsa fisheries of the northern Bay of Bengal region. Such investments encompass a wholesome approach, including more governmental initiatives for conservation and management. [ABSTRACT FROM AUTHOR]

Knowledge of platform ecology is necessary to best inform decommissioning practice. Remotely operated vehicle (ROV) video is often collected during standard industry operations and may provide insight into the marine life associating with offshore platforms, however, the utility of this video for ecological assessments remains unclear. Archival ROV video surveys at the Wandoo oil platforms on Australia's North West Shelf was evaluated for its utility, with only 4.9% of imagery usable for standardised ecological studies. Based on the subset of usable ROV video, the influence of depth and structural complexity on attributes of the fish assemblage on the Wandoo oil platforms was examined. Vertical ROV transects on three vertical shafts on the Wandoo platforms were stratified into 10 m depth strata from 0 to 50 m, with 111 fish taxa from 25 families identified and counted across all depth strata. At both platforms, taxonomic richness and abundance was significantly highest in shallow regions and declined with depth. Small reef fish were predominantly associated with structurally complex habitat in shallow regions (<22 m), whilst large demersal species dominated below 32 m. Future decommissioning policy in Australia should consider the vertical fish distributions and the importance of shallow sections of platforms. Finally, the dearth of usable video was due to the haphazard method of collection and it is recommended that future surveys should be conducted according to scientific standards to ensure greater utility of the video for both industry use and scientific research. [ABSTRACT FROM AUTHOR]

The brown meagre (Sciaena umbra) is an endangered species, which requires specific protection measures to ensure its conservation. These measures need to be informed by high-quality scientific knowledge on their space use patterns. Here, we used acoustic telemetry to assess its seasonal movement patterns and habitat use within a marine protected area (MPA). Our results suggested that S. umbra is a highly sedentary species (home range < 1.0 km2) and, therefore, the MPA is extensive enough to protect the local population. Their population was discretely distributed in two main areas within the MPA, which was likely a result of habitat segregation and density-dependent movements. The temporal variability of their movements further uncovered when and where spawning occurs (mainly, but probably not only, in the fully protected area in June) and indicated that spillover of this species is limited but still possible. Overall, we highlight the importance of MPAs in the recovery of S. umbra, we advocate the need to perpetuate the current national fishing bans and extend it to other countries in the Mediterranean region, and we emphasize that considering the fine-scale movements of S. umbra in future management actions is key to achieving a successful recovery of their populations. [ABSTRACT FROM AUTHOR]

By the 1980s, after decades of declining numbers in the mid‐1900s, Coho salmon (Oncorhynchus kisutch) were considered extirpated from the interior Columbia River. In the mid‐1990s, the Confederated Tribes of the Umatilla Indian Reservation, the Confederated Tribes and Bands of the Yakama Nation, and the Nez Perce Tribe began successful reintroduction programs of Coho salmon upstream of Bonneville Dam, but which were initially sourced from lower Columbia River hatcheries. Here we present the first Coho salmon parentage‐based tagging (PBT) baseline from seven hatchery programs located in the interior Columbia River basin, and two sites at or downstream of Bonneville Dam, composed of over 32,000 broodstock samples. Analyses of baseline collections revealed that genetic structure followed a temporal pattern based on 3‐year broodlines rather than geographic location or stocking history. Across hatchery programs, similar levels of genetic diversity was present. The PBT baseline provided multiple direct applications such as identification of origin for Coho salmon collected in a mixed stock at Priest Rapids Dam and the detection of the proportion and distribution of hatchery‐origin fish on the spawning grounds in the Methow River basin. The PBT baseline for Coho salmon is freely available for use and can be downloaded from FishGen.net. [ABSTRACT FROM AUTHOR]

This paper presents a bibliometric analysis of scientific research on renewable energy in Africa, a rapidly growing field driven by the need for sustainable and accessible energy solutions. It highlights Africa's role as a hub for renewable energy innovation, with local researchers collaborating with global institutions to address the continent's unique energy challenges. This synergy is enhancing energy access in African communities and contributing to the global advancement of renewable technologies. The study meticulously examines 3,109 scientific publications from the Scopus database, spanning from 1979 to 2022. It analyzes the evolution, geographical distribution, and impact of these publications, with a focus on international collaborations and scientific output. Findings indicate that South Africa leads in productivity with 962 publications and hosts the top affiliating institutions in this domain. The study also reveals an exponential increase in renewable energy research, particularly from South Africa, the United States, and the United Kingdom, emphasizing the need for more collaborative efforts and knowledge exchange globally. This analysis provides critical insights into the current landscape of renewable energy research and pinpoints areas ripe for further exploration and development in this vital sector. [ABSTRACT FROM AUTHOR]

The advance of deforestation impacts freshwater ecosystems and, consequently, the environmental heterogeneity and associated biodiversity. Our objective was to examine the effect of deforestation on environmental heterogeneity (EH), species richness (SR), and functional richness (FRic) and the role of EH in the abundance of species and functional groups of stream fish. We analyzed 71 streams of the Acará-Capim basin, eastern Amazon. We used path analysis to assess whether land-use types influence the predominant vegetation cover and channel characteristics, and their indirect effect on EH, SR, and FRic. Taxa indicator threshold analysis was used to assess whether fish species and functional groups act as bioindicators of EH and percentage of forest in total catchment (PFTC). The higher percentage of secondary forest in total catchment (PSFTC) favored herbaceous understory plants and SR. The largest amount of sediments and higher PSFTC negatively influenced EH. FRic was not influenced by any of the variables. Species with high swimming ability that belong to the trophic guilds piscivores and invertivores, are associated with high values of EH and PFTC. Our results may be useful for riparian forest restoration projects, as we show which variables increase or decrease EH and demonstrate how bioindicators respond to this. [ABSTRACT FROM AUTHOR]

This article highlights recent successes and failures in efforts to manage Arctic marine living resources to improve our understanding of institutional resilience--that is, the ability of cooperative institutions to maintain their performance despite severe disruptions to their operating environments. Rising ocean temperatures and other impacts of climate change may alter the spatial distribution of fish stocks, including their relative attachment to exclusive economic zones and their availability on the high seas. As evident in the examined Arctic cases, which involve the world's largest stocks of cod, herring and mackerel, such changes may complicate core resource management tasks, including the regulatory task of reaching an agreement among user states on quotas and other restraints that align with scientific advice. The cross-case variance in regulatory resilience to climate-related and other changes in cooperative circumstances sheds light on general propositions regarding the drivers and inhibitors of institutional resilience, including institutional characteristics and the severity of the political challenges posed by changing circumstances. [ABSTRACT FROM AUTHOR]

The idea of the article was to verify the thesis that acoustic studies of ichthyofauna in lakes provide sufficient information to determine the necessity (or lack thereof) of carrying out a full procedure for assessing the ecological status based on fish. The manuscript compares acoustic data collected in 2008 and 2021 in Lake Dejguny (Poland) as a result of acquisition carried out with the same EY-500 echosounder, on the same routes (transects), and the echogram analyses were carried out using software dedicated to this echosounder. Target strength (TS) distribution was determined in the lake and in individual water layers with a thickness of 2 m, as well as, using the mapping method, changes in the distribution of fish in selected water layers. Large changes in TS distribution in the vertical profile were demonstrated between both years of the study, as well as a clear reduction in the space available for fish in waters below 24 m in 2021, which was associated with a reduction in the concentration of dissolved oxygen below this depth to a value lower than 2.5 mg L−1. It was suggested that it could be possible to develop a simple index enabling the assessment of changes in fish structure, based, similarly to the Large Fish Index, on the ratio of the number of large fish to small fish. The obtained results confirmed that the proposed methods of acoustic data analysis can be the basis for the decision on the necessity (or lack thereof) of conducting an assessment using the Polish national LFI-EN method based on the results of one-off fishing with Nordic multimesh gillnets. [ABSTRACT FROM AUTHOR]