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Fishes exhibit a diverse range of traits encompassing life‐history strategies, feeding behaviours and spawning behaviours. These traits mediate fish population responses to changing environmental conditions such as those caused by anthropogenic stressors. The Conasauga River, located in northwestern Georgia and southeastern Tennessee, USA, hosts a diverse assemblage of over 75 species of freshwater fish, some of which are locally or regionally endemic, and many of which are imperilled. Annual monitoring data have shown population declines in multiple fish species of conservation concern in the Conasauga River since at least the 1990s, raising the possibility that other taxa could be declining as well. We quantified temporal changes in fish communities at six shoal sites sampled annually in most years from 1996 to 2022, and asked whether species traits hypothesized to underlie population vulnerability to environmental alteration were correlated with species‐specific trends for 32 taxa. We estimated that total counts of fish in annual samples declined by ~2% per year, although declines were uneven among species and generally greater for less abundant taxa. Tests for species traits corresponding to temporal population trends provided evidence that crevice‐spawning minnows and smaller‐bodied taxa had steeper declines compared with broadcast spawners and larger, longer‐lived, more fecund taxa. Lower abundance, reliance on a particular habitat feature, and life‐history traits that may limit population resilience to disturbance may all prove useful for identifying riverine fishes at particular risk of future population decline. [ABSTRACT FROM AUTHOR]

Large-bodied animals, such as the Mekong giant catfish (Pangasianodon gigas), may modify prey communities and affect their potential competitors for food resources by consuming large quantities of prey. The Mekong giant catfish is a key representative of freshwater megafauna and is stocked in reservoirs in Thailand for species conservation and fishery stock enhancement. However, their biological interactions with other sympatric animals remain unclear. Here, we aimed to investigate the trophic niche of the Mekong giant catfish in a Thai reservoir by comparing stable carbon and nitrogen isotope ratios (δ13C and δ15N, respectively) and fatty acid (FA) composition with those of five other sympatric fish species. The δ13C value of the Mekong giant catfish was –24.4 ± 1.0‰ (mean ± SD), the second highest among the sympatric fish species, suggesting relatively weak reliance on phytoplankton-based food chains. The δ15N value of the Mekong giant catfish was 10.7 ± 0.4‰, intermediate between those of herbivorous and carnivorous fishes, indicating that it is not a primary consumer. The FA composition of the Mekong giant catfish significantly differed from those of the other fish species and was characterized by a large proportion of long-chain FA, including 22:6n-3, 20:5n-3, and 20:1n-9. The δ13C, δ15N, and FA signatures suggest that the Mekong giant catfish occupy distinct trophic niches in food webs. Our results highlight that it is necessary to monitor the ecological impacts of released Mekong giant catfish on lower-level consumers through their foraging in receiving reservoirs. [ABSTRACT FROM AUTHOR]

Aim: Rare species make substantial contributions to coastal ecosystem functions. Functional rarity (FR) and phylogenetic rarity (PR) are important features for biodiversity conservation. This work aimed to discuss the necessity and reasonableness of conserving fish FR and PR in coastal seas. Location: China. Methods: By compiling historical fish investigation data, joint species distribution modelling (JSDM) was applied to model fish communities in coastal China Seas. Biogeographic patterns of FR and PR were explored, and the effectiveness of current MPA networks in terms of match/mismatch with the hotspots of rarity was assessed. Results: A total of 44 functionally rare species and 22 phylogenetically rare species were identified. Six of these species were both functionally and phylogenetically rare, and only one was listed as endangered on the Red List of the International Union for Conservation of Nature (IUCN). Functional rarity hotspots covered 10.27% of the coastal areas, which geographically converged in the southern and eastern coast of Taiwan, the Yangtze River Estuary and the Yellow River Estuary. Phylogenetic rarity hotspots only covered 3.06% of the coastal areas, which were sporadically distributed in the coastal East China Sea, the Bohai Sea and the northern Yellow Sea. Current marine‐protected areas (MPAs) only represented 16.16% of the FR hotspots and 20.48% of the PR hotspots, indicating substantial mismatched areas between the MPAs and the hotspots of FR and PR. Main Conclusions: Only considering threatened species in conservation practices will omit functionally and phylogenetically rare species because FR and PR are not necessarily correlated with species threat status on the IUCN Red List. Functional rarity hotspots do not necessarily overlap with PR hotspots, and current MPAs mismatch the majority of these areas. We therefore advocate that conservation prioritization and expansion of MPA networks should account for FR and PR both at the species and site levels. [ABSTRACT FROM AUTHOR]

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

It's essential to identify the priority conservation species in the habitat restoration and biodiversity conservation. Generally, people select the valuable fishes or the commercial fishes as target species in basins, according to experts' experience rather than the scientific evaluation. With the influence of urban development, construction of water conservancy facilities and human activities, the river habitat of the Shaying River (Xuchang section) is poor. Fish conservation studies play an important part in the habitat restoration of this river section. Thus, we studied the evaluation method for the priority protection of fishes based on multiple ecological dimensions. The method including six multidimensional indicators, namely, habitat suitability, ecological stability, species endangerment criteria, intensity of human interference, genetic value, and species value. Then, we determined the indicator weights by the analytic hierarchy process (AHP), and assessed the protection priority of fishes based on various assessment criteria and comprehensive qualitative or quantitative analyses. The result shows that Ctenopharyngodon idellus, Opsariichthys bidens, and Culter alburnus Basilewsky have priority for protection, coinciding with the status in the basin. Overall, this study complements the existing indicator species selection methods, and is more scientific and comprehensive, providing an effective method for priority protection species and river habitat restoration projects. [ABSTRACT FROM AUTHOR]

Swordtip squid (Uroteuthis edulis), which is sometimes eaten alive (lively squid) in northwest Kyushu, Japan, is an economically important fish species in the region. However, the total catch of this species in Japan has declined by more than 80% in the last three decades. To understand and predict the spatio‐temporal distribution of fish species, we developed a one‐dimensional ecosystem (NPZD) model and a habitat suitability index (HSI) model for southwest Iki Island, northwest Kyushu, Japan. Subsequently, we conducted three numerical experiments with the HSI model, with and without the NPZD model data (with the NPZD model data: phytoplankton or zooplankton concentrations, without the NPZD model data: only the physical data of the ocean). In the HSI model with zooplankton concentrations, we found a stronger positive relationship between the HSI model values and the daily fisheries catch data of U. edulis than that using only the physical variables of the ocean as the environmental parameters. Our study thus indicates that the performance of the fishing ground prediction model will improve by utilizing the lower trophic ecosystem model such as zooplankton concentrations. Furthermore, our results would provide important implications for the efficiency of fishing operations and the conservation and management of this species. [ABSTRACT FROM AUTHOR]

Global warming affects the metabolism of ectothermic aquatic breathers forcing them to migrate and undergo high‐latitudinal distribution shifts to circumvent the temperature‐induced mismatch between increased metabolic demand and reduced water oxygen availability. Here the authors examined the effects of temperature on oxygen consumption rates in an Arctic stenotherm, the Greenland halibut Reinhardtius hippoglossoides, and calculated the optimal temperature for maximum aerobic scope, AS(Topt,AS), which was found to be 2.44°C. They also investigated cardiac performance as limiting the oxygen transport chain at high temperatures by measuring maximum heart rate (fHmax) over acute temperature increases and found various metrics related to fHmax to be at least 3.2°C higher than Topt,AS. The authors' measured Topt,AS closely reflected in situ temperature occurrences of Greenland halibut from long‐term tagging studies, showing that AS of the species is adapted to its habitat temperature, and is thus a good proxy for the species' sensitivity to environmental warming. The authors did not find a close connection between fHmax and Topt,AS, suggesting that cardiac performance is not limiting for the oxygen transport chain at high temperatures in this particular Arctic stenotherm. The authors' estimate of the thermal envelope for AS of Greenland halibut was from −1.89 to 8.07°C, which is exceptionally narrow compared to most other species of fish. As ocean temperatures increase most rapidly in the Arctic in response to climate change, and species in these areas have limited possibility for further poleward‐range shifts, these results suggest potential severe effects of global warming on Arctic stenotherms, such as the Greenland halibut. The considerable economic importance of the species raises concerns for future fisheries and species conservation of Arctic stenotherms in the Northern Hemisphere. [ABSTRACT FROM AUTHOR]

Freshwater fish populations are in steep decline, prompting conservation measures and a need for their evaluation. Fish are increasingly monitored with passive integrated transponders (PIT), although the suitability of this tagging technique has not yet been validated for most European target species of conservation. Consequently, this study tested the effect of commonly used 12 mm full-duplex (FDX) PIT tags implanted into the abdominal cavity of common nase (Chondrostoma nasus L.) and European barbel (Barbus barbus L.). A controlled laboratory setup was used to compare survival, growth (both length and weight) and tag retention for two different size classes of sub-adults over 61 days. Survival in the treatment groups was high (96.7–100%) and not statistically different from the control groups (97.5–100%). Highest mortality occurred in small tagged barbel (n = 4; 96.7% survival), while no mortality occurred in large tagged nase. Mean growth rates for tagged fish (2.28 mm, 3.26 g) were similar to those of control fish (2.77 mm, 3.59 g). Overall tag retention rate was 99.0% and tag loss only occurred in nase. The results of this study demonstrate the suitability of PIT injection in the body cavity of nase and barbel > 100 mm TL, which is of high methodological importance given the increasing role these species play in PIT tag-based assessments of freshwater fish conservation in European rivers. [ABSTRACT FROM AUTHOR]

Lumpfish are a commercially significant marine fish that are harvested in roe fisheries and used as cleaner fish in salmon farming, however, little is known of the environmental factors shaping the ecological niche of the species at global scale. As captive reared lumpfish are sensitive to warm water, the geographic distribution of wild populations may change as sea temperatures rise under expected climate change. After investigating the ecological niche of the lumpfish using Species Distribution Models, we found that nitrate concentration, ice cover, diffuse attenuation, and temperature predicted the probability of lumpfish occurrence. Through modelling distribution under expected climate change forecasts within a realistic scenario, we found reduced probability of lumpfish occurrence in areas which currently support roe harvest and cleaner fish industry. Future conservation of the species and fisheries management should account for changes in lumpfish distribution as the range shifts northward. [ABSTRACT FROM AUTHOR]

Atlantic Goliath Grouper, Epinephelus itajara, the largest grouper in the western North Atlantic, exhibits life history characteristics (e.g., it is slow-growing, long-lived, and late-maturing) that make it particularly susceptible to fishing pressure. Otoliths, the structure typically processed for age determination, are usually collected as part of fishery monitoring, but otoliths are not available from Goliath Grouper due to a harvest moratorium enacted in 1990 for United States waters. Alternative structures—such as dorsal fin rays or spines—can be acquired for ageing via nonlethal sampling and may provide reliable age estimates. Since 2006, the Florida Fish and Wildlife Conservation Commission (FWC) has been collecting incidental Goliath Grouper samples from mortality events including those from cold kills and red tides. Corresponding otolith, dorsal fin ray and dorsal fin spine samples were compared to determine the accuracy and precision of the external ageing structures. Marginal increment analyses indicated that annulus (translucent zone) deposition occurred primarily in March–June on spines and in April–June on rays. While ages determined from both rays and spines exhibited high precision, the accuracy compared to otolith ages was low as a result of systematic underageing of both external structures, particularly at the oldest age classes. A correction factor was applied to rays and spines that remedied the underageing, but the correction factor was more successful for spines. An analysis of ray and spine section accuracy based on nonlethal structure removal from the fish (i.e., comparing ages from sections at the base of the structure within the body to those sectioned from the external surface of the body) determined that spines can be accurately aged when sampled distal of the base of the structure, but that rays cannot. Nonlethal sampling and ageing of Goliath Grouper spines facilitated by public participation could address management goals and help determine the offshore population age structure. Simultaneously, it could contribute critical data needed for a traditional stock assessment, should such a path be warranted by the recovery or management of the species. [ABSTRACT FROM AUTHOR]

Florida promotes itself as the fishing capital of the world, and fishing is one of the state's most popular recreational activities. As the state faces increasing anthropogenic and natural environmental stressors, effective resource management is of paramount importance in sustaining healthy fisheries. The Fisheries Independent Monitoring (FIM) program of the Florida Fish and Wildlife Conservation Commission's Fish and Wildlife Research Institute regularly monitors relative abundance of various size and age classes of multiple sport fish species (e.g., Centropomus undecimalis common snook, Sciaenops ocellatus red drum, Cynoscion nebulosus spotted seatrout) to provide timely data to fisheries managers. The FIM program samples seven major Florida estuaries, including four that the National Estuary Program has designated as estuaries of national significance (Tampa Bay, Sarasota Bay, Coastal and Heartland, and Indian River Lagoon). Although the FIM program sampling design is consistent and results are comparable among estuaries, the environmental perturbations, available habitats, habitat use by resource species, and recruitment dynamics vary, which can result in different abundance trends among estuaries. The goal of this study was to assess the role of early life stages as refuges for adult populations for two inshore sport fish species and examine their potential in forecasting relative abundance of fishery stocks. We present long-term abundance trends and assess lagged regressions among size or age classes to reveal the importance of size class refuges and identify preferred habitats that are estuary- and age class-specific, providing tools for better managing fishery stocks and habitats. [ABSTRACT FROM AUTHOR]

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

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

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

Simple Summary: The whitemouth croaker Micropogonias furnieri is an important fishery resource on the southwest Atlantic coast. Despite being heavily exploited, there are a few uncertainties regarding the population structure in the transition area between the tropical and warm temperate zones (South Brazilian Bight). In the State of Rio de Janeiro (the northern part of this area), local environmental conditions, such as an upwelling phenomena and large estuarine bays, together with contributions of continental drainage and anthropogenic activities, could determine different croaker populations. The aim of this study was to assess the fine-scale population structure of this species in three localities in Rio de Janeiro State (Brazil) and to compare it with previous studies that used different approaches. Through the combined use of genetic markers (nuclear microsatellites) and otolith signatures (morphometry and chemistry), two genotypic (North + Center/South) and three phenotypic (North + Center + South) populations were found. These results could contribute to a better understanding of the M. furnieri population dynamics and allow a rational management of this important fishing resource. The inshore area of the Southwestern Atlantic between 22 °S and 29 °S (South Brazilian Bight) is a transitional climatic zone, where the tropical and warm temperate provinces mix. In its northern part, i.e., in the coastal waters of Rio de Janeiro, Brazil, local oceanographic conditions, such as upwelling in the north, and great bays with different degrees of anthropogenic influences in the center and south can determine the population structure of several fish stocks. The Whitemouth croaker (Micropogonias furnieri) is one the most heavily exploited fishing resources in this area, but there are still some doubts about its population structure. In this study, through combined analyses using nuclear genetic markers and morphological and geochemical signatures of otoliths, a divergence of individuals between two populations was identified using microsatellites, while a finer spatial structure with three populations (north, center and south, respectively) was found based on otolith shapes and elemental signatures. This regional population structure may have direct implications for rational fisheries management and conservation of the species. [ABSTRACT FROM AUTHOR]

Diet plasticity is a common behavior exhibited by piscivores to sustain predator biomass when preferred prey biomass is reduced. Invasive piscivore diet plasticity could complicate suppression success; thus, understanding invasive predator consumption is insightful to meeting conservation targets. Here, we determine if diet plasticity exists in an invasive apex piscivore and whether plasticity could influence native species recovery benchmarks and invasive species suppression goals. We compared diet and stable isotope signatures of invasive lake trout and native Yellowstone cutthroat trout (cutthroat trout) from Yellowstone Lake, Wyoming, U.S.A. as a function of no, low-, moderate-, and high-lake trout density states. Lake trout exhibited plasticity in relation to their density; consumption of cutthroat trout decreased 5-fold (diet proportion from 0.89 to 0.18) from low- to high-density state. During the high-density state, lake trout switched to amphipods, which were also consumed by cutthroat trout, resulting in high diet overlap (Schoener's index value, D = 0.68) between the species. As suppression reduced lake trout densities (moderate-density state), more cutthroat trout were consumed (proportion of cutthroat trout = 0.42), and diet overlap was released between the species (D = 0.30). A shift in lake trout δ13C signatures from the high- to the moderate-density state also corroborated increased consumption of cutthroat trout and lake trout diet plasticity. Observed declines in lake trout are not commensurate with expected cutthroat trout recovery due to lake trout diet plasticity. The abundance of the native species in need of conservation may take longer to recover due to the diet plasticity of the invasive species. The changes observed in diet, diet overlap, and isotopes associated with predator suppression provides more insight into conservation and suppression dynamics than using predator and prey biomass alone. By understanding these dynamics, we can better prepare conservation programs for potential feedbacks caused by invasive species suppression. [ABSTRACT FROM AUTHOR]

Wild fish populations are unceasingly diminishing in the rivers, ox‐bow lakes and floodplains in the Southwestern region of Bangladesh. Investigating the population status of vulnerable wild fish species are vital for the management and conservation of that species. This study aimed to identify the intra‐specific morphological variation and determine the population status of Lepidocephalichthys annandalei, in two rivers, the Nabaganga River in Jhenaidah (NRJ) and the Bhairab River in Jashore (BRJ) as well as a flood plain, the Dhakuria Beel in Jashore (DBJ) from Southwestern Bangladesh. Significant differences were observed in seven conventional and five truss‐based characters in univariate statistics. Conventional and truss‐network results from principal component analysis and CVA exhibited that populations were entirely intermixed, creating a compact cluster within intra‐population stages. Four principal components explained 51.93% of the variation in conventional morphometric characters and truss‐based characters. A UPGMA dendrogram was independently developed based on conventional and truss‐based morphometric characters. Among the individuals of NRJ and BRJ populations confirmed the presence of out‐group rather than the DBJ based on morphometric (conventional and truss) features. These notable isolations of populations of this species were supposed to be geographic disconnection and abiotic parameters. The evidence ensuing from the present study would be valuable for genetic studies as well as for in situ management. [ABSTRACT FROM AUTHOR]

The article discusses the Great Goliath Grouper Count (GGGC), a program initiated in 2010 by Florida Sea Grant and the Florida Fish and Wildlife Conservation Commission (FWC) to collect data on the Atlantic goliath grouper. The goliath grouper is a large reef species that was overfished and experienced population declines in the past. The GGGC utilizes trained divers who follow standardized protocols to report data on the number, size, and location of goliath groupers observed during underwater surveys. The program has expanded to include the entire state of Florida and has provided valuable data for stock assessments and fisheries management. [Extracted from the article]

Trophic ecology studies on predator–prey interactions reveal insights into ecological communities and help understand a species' role in the food web by contributing to improved fisheries management and conservation capabilities. Understanding the ecological role of overexploited and endangered predators is essential to deciphering how their feeding behaviour influences food web dynamics. In this study, the authors investigated the feeding behaviour of the common and IUCN‐listed Near Threatened (NT) thornback ray Raja clavata, using carbon and nitrogen stable isotope and stomach content analysis (SCA). It has recently suffered an 87% decline in reported catches from the Sea of Marmara within the last decade. These results show that thornback ray mainly feeds on teleost species, except in summer, with both methods showing this species changes its diet ontogenetically by SCA. This ontogenetic diet shift was at lengths 40–50 cm by changing group preferences from Crustacea to Teleostei. MixSIAR results showed that both adult and juvenile individuals of R. clavata feed mainly on the crustaceans, but the contribution of teleosts represented by Trachurus sp. was very low (<15%). The trophic position increased total length and was higher than other batoid species in the Sea of Marmara. [ABSTRACT FROM AUTHOR]

Actinopyga echinites are among the commercially exploited sea cucumbers; however, limited studies hinder the management interventions for the sustainability of the resource. This study investigates the density and size distribution of A. echinites populations in Cabgan Island, Barobo, Surigao del Sur from March-August 2021 with two stations (shallow seagrass beds as Station 1 and algal flats as Station 2) having three plots (100 m²) laid as monitoring stations. The results revealed the population density of A. echinites ranged from 567-2,567 ind/ha with a mean of 1,572 ± 225 ind/ha in Station 1 and 733-2,400 ind/ha and a mean of 1,389 ± 178 ind/ha in Station 2. Significant differences were only observed across months in each station (P = 0.00) and their interaction between months and stations (P = 0.01). A. echinites had a mean length of 7.58 ± 0.26 cm and weight of 31.39 ± 1.62 g for Station 1 and 7.84 ± 0.47 cm and 39.01 ± 3.91 g for Station 2. Specimens in Station 2 had a greater length and significantly heavier weight than in Station 1 (P = 0.00). Across months, significant differences were recorded for the specimen's length in Station 1 and weight for both stations. The length of A. echinites ranged from 4-12 cm and 4-13.5 cm in Stations 1 and 2, respectively, and weight of 5-129 g in both stations. The highest frequencies were recorded at 7 cm in both stations and shifted to 9 cm. Weight distributions showed the highest frequencies in 35 g in the two stations. The present study shows that the population is still abundant and is more influenced by the sampling months than the stations. The species are smaller compared to other studies and might exhibit habitat preferences. Weight size distribution varied across months and could be related to their reproduction. The study provides significant insights needed for this species' conservation and fishery management. [ABSTRACT FROM AUTHOR]

The queen conch (Aliger gigas) is a culturally and economically important molluskan fishery resource in the Caribbean region showing increasing signs of over harvest. Shallow-water distribution and large size facilitate capture, and internal fertilization and density-dependent reproduction make managing for reproductive biology critical to stock rehabilitation. In fact, the natural lifetime fecundity of conch is very high but most fisheries in the region harvest conch before even a small fraction of that reproductive potential can be attained. The goal of this review is to provide an up-to-date synthesis of the vast research literature on queen conch biology (spanning >60 years) and to discuss how knowledge of reproduction in conch can help to guide field surveys, fishery management decisions, and stock recovery projects. The review covers the subjects of anatomy, maturation and fecundity as they relate to conch age and size, reproductive behavior including migrations, seasonality, mating, and egg-laying, and the influences of both environmental and demographic variables on reproductive potential. Successes and failures under different forms of management practice are discussed as they relate to reproductive biology and recommendations are made for future research and fishery management alternatives. Successful management will require multiple regulatory approaches. [ABSTRACT FROM AUTHOR]

Understanding the effects of hydrology on fish populations is essential to managing for native fish conservation. However, despite decades of research illustrating streamflow influences on fish habitat, reproduction, and survival, biologists remain challenged when tasked with predicting how fish populations will respond to changes in flow regimes. This uncertainty stems from insufficient understanding of the context‐dependent mechanisms underlying fish responses to, for example, periods of reduced flow or altered frequency of high‐flow events. We aim to address this gap by drawing on previous research to hypothesize mechanisms by which low and high flows influence fish populations and communities, identifying challenges that stem from data limitations and ecological complexity, and outlining research directions that can advance an empirical basis for prediction. Focusing flow ecology research on testing and refining mechanistic hypotheses can help narrow management uncertainties and better support species conservation in changing flow regimes. [ABSTRACT FROM AUTHOR]

Aquatic food‐web studies involving fish and using stable isotope analysis typically sample fish white muscle, which generally requires the fish to be euthanised. Alternatively, fin tissue can be sampled non‐lethally, avoiding the need to euthanise an animal to obtain what is usually a relatively small tissue sample. We set out to develop equations for converting δ13C and δ15N values from derived non‐lethally sampled fin tissue to equivalent white muscle tissue, for use in food‐web studies. We explored δ13C and δ15N values of paired fin‐clips and white muscle from two species of anguillid fishes, the endemic longfin eel (Anguilla dieffenbachii), and the Australasian shortfin eel (A. australis), sourced from multiple studies spread throughout New Zealand. We also examined the effect of lipid extraction on δ13C and δ15N, which reduced variability of δ13C when compared to untreated samples. We were also able to estimate δ13C values of equivalent lipid‐extracted muscle samples directly from untreated fin. For δ15N, paired untreated fin and muscle values were not statistically different so fin δ15N can be used as a direct estimate of muscle δ15N. Solvent lipid extraction with a methanol–chloroform mixture, however, altered δ15N values and increased variability, so should be avoided. We present equations to estimate lipid‐corrected δ13C values of muscle tissue for use in stable isotope studies of freshwater anguillids, avoiding euthanasia. Our results demonstrate that δ13C and δ15N values can be accurately derived from non‐lethally obtained fin clips, reducing unnecessary mortality in fish species of conservation concern. [ABSTRACT FROM AUTHOR]

• Bailong River's ecological health was evaluated by using a multi-indicator system. • An evaluation system covering natural attributes and functionality was established. • The Bailong River is in a sub-healthy condition, with weak spatial heterogeneity. • Restoration focuses on river habitat and fish species conservation. • To a certain extent, it fills the gap in the study of the health of the Bailong River. The health of watershed ecology is mutually constrained by the sustainable development of the regional economy and society, and health assessment helps to identify the ecological status quo. As one of the "ethnic corridors", the Bailong River has become a region of human solid interference. Therefore, this study constructed an indicator evaluation system to reflect rivers' natural attributes and functionality by analyzing candidate indicators' sensitivity, principal components, and independence. The weight of the indicators was determined using the Analytic Hierarchy Process combined with expert opinions. The ecological status of the Bailong River was evaluated through field monitoring data, and ecological restoration suggestions were proposed. The results show that Bailong River's comprehensive score is 58.27, indicating sub-health. The constructed evaluation system includes thirteen indicators, of which 53.84% are in an ideal state, 15.39% are healthy, 7.69% are sub-health, 15.39% are unhealthy, and 7.69% are pathological, with weak spatial heterogeneity. The evaluation results of the guidelines show that the state of "cleanliness" and "service" is ideal, "circulation" and "life" are healthy, and "physical structure" is worrying. Based on this, the ecological restoration and protection of the Bailong River in the future should focus on the following aspects: improving methods and theories, restoring the habitat environment of the river, ensuring water quantity, improving water quality, and conserving fish species. This study can provide necessary theoretical support for the ecological restoration of severely disturbed water-deficient rivers and lakes in northern China. [ABSTRACT FROM AUTHOR]

A lack of an updated checklist of freshwater fish species from Lake Dongting is a great hindrance to further biodiversity analysis. A seasonal survey of fishes in the lake was conducted from October 2017 to January 2019. Based on the data obtained during the field survey and coupled with known literature and the latest taxonomic development of relevant taxa, the species checklist of fishes from Lake Dongting was updated. A total of 130 species from 12 orders, 30 families and 76 genera has been documented, containing 126 native species and four alien species. Its fish fauna is dominated by the Xenocyprididae that has the highest number of included species (30), followed by the Gobionidae (25) and Acheilognathidae (11). This checklist comprises 20 species undergoing nomenclatural changes and 11 new records, eight of which are native and three exotic. It excludes 20 species, which have been reported in error in historical works, due to synonyms, erroneous records, taxonomic changes and unconfirmed records. Unsampled in this survey were 34 species that are ecologically specialised: migratory, rheophilic, predatory, shellfish-dependent or pelagic-egg-spawning. While some of these species eluded capture likely due to the paucity of population, others may have been extirpated in Lake Dongting perhaps owing to human perturbations, such as river damming across affluents or the Chang-Jiang mainstem, sand dredging, overfishing or water pollution. The updated checklist lays a sound foundation for biodiversity conservation of fishes in Lake Dongting. [ABSTRACT FROM AUTHOR]

Globally, policies aiming for conservation of species, free‐flowing rivers, and promotion of hydroelectricity as renewable energy and as a means to decarbonize energy systems generate trade‐offs between protecting freshwater fauna and development of hydropower. Hydroelectric turbines put fish at risk of severe injury during passage. Therefore, comprehensive, reliable analyses of turbine‐induced fish mortality are pivotal to support an informed debate on the sustainability of hydropower (i.e., how much a society is willing to pay in terms of costs incurred on rivers and their biota). We compiled and examined a comprehensive, global data set of turbine fish‐mortality assessments involving >275,000 individual fish of 75 species to estimate mortality across turbine types and fish species. Average fish mortality from hydroelectric turbines was 22.3% (95% CI 17.5–26.7%) when accounting for common uncertainties related to empirical estimates (e.g., handling‐ or catch‐related effects). Mortality estimates were highly variable among and within different turbine types, study methods, and taxa. Technical configurations of hydroelectric turbines that successfully reduce fish mortality and fish‐protective hydropower operation as a global standard could balance the need for renewable energy with protection of fish biodiversity. [ABSTRACT FROM AUTHOR]

Inherent differences between baited remote video versus diver-operated video survey methodologies may influence their ability to detect effects of fishing. Here, the ability of no-take zones (NTZs) to provide protection for legal-sized fish from targeted species within the Ningaloo Marine Park (NMP) was assessed using both baited remote underwater stereo-video (stereo-BRUV) and diver-operated stereo-video (stereo-DOV). The relative abundance of legal-sized individuals of three recreationally targeted fish species, spangled emperor Lethrinus nebulosus, chinaman cod Epinephelus rivulatus and goldspotted trevally Carangoides fulvoguttatus, were examined using both methodologies inside and outside six NTZs across the NMP. Stereo-BRUVs found positive effects of protection on the relative abundance of legal-size C. fulvoguttatus and L. nebulosus in NTZs. Stereo-DOVs, however, did not detect any differences in relative abundances and sizes of these species between areas opened and closed to fishing. These contrasting results suggest that choice of sampling methodology can influence interpretations of the ability of NTZs to provide adequate levels of protection for target species. Our results suggest that stereo-BRUVs are a superior technique to stereo-DOVs for assessing the effectiveness of no-take zones for protection of fishery target species, reflecting bait attraction and an absence of diver influence on fish behaviour. [ABSTRACT FROM AUTHOR]

Chondrichthyan fishes are ecologically and economically important, yet many are overfished or at elevated risk of extinction. Researchers report a desire to perform policy‐relevant science that can generate data in support of effective conservation and management plans, but also report a lack of clarity about how to most effectively to do that. To address this gap, we created a list of research and policy priorities for chondrichthyan species of conservation concern in US waters using a modified expert solicitation horizon scan approach. Thirty‐five policy‐relevant research priorities and twenty‐seven policy priorities are presented here, a list which can help to guide scientists and conservationists to maximize the effectiveness of their research and policy advocacy. [ABSTRACT FROM AUTHOR]

Understanding genetic connectivity plays a crucial role in species conservation decisions, and genetic connectivity is an important component of modern fisheries management. In this study, we investigated the population genetics of four endemic Lates species of Lake Tanganyika (Lates stappersii , L. microlepis , L. mariae , and L. angustifrons) using reduced-representation genomic sequencing methods. We find the four species to be strongly differentiated from one another (mean interspecific F ST = 0.665), with no evidence for contemporary admixture. We also find evidence for strong genetic structure within L. mariae , with the majority of individuals from the most southern sampling site forming a genetic group that is distinct from the individuals at other sampling sites. We find evidence for much weaker structure within the other three species (L. stappersii, L. microlepis , and L. angustifrons). Our ability to detect this weak structure despite small and unbalanced sample sizes and imprecise geographic sampling locations suggests the possibility for further structure undetected in our study. We call for further research into the origins of the genetic differentiation in these four species—particularly that of L. mariae —which may be important for conservation and management of this culturally and economically important clade of fishes. [ABSTRACT FROM AUTHOR]

Amid a time of unprecedented social‐ecological change, professionals within and outside of the US wildlife conservation community have called for transformation of existing processes and structures to ensure that the benefits of wildlife conservation can be realized well into the future. Current momentum behind an initiative to help increase conservation relevancy among population segments that have historically been underserved by the conservation community is underway. Sustainable institutional change will not be realized, however, without attending to internal cultural change within the conservation community itself. Although elements of an ideal institution have been suggested, specific interventions related to institutional culture need deeper exploration. State fish and wildlife agencies—a primary organizational actor within the conservation community—play a central role in institutional transformation. Using a systems framework, this essay describes key leverage points for cultural change for which interventions could result in sustainable culture shifts. Five possible interventions are introduced to stimulate conversation among conservation practitioners seeking to initiate transformational change within their specific cultural contexts. Amid a time of unprecedented social change, professionals within and outside of the US wildlife conservation community have called for transformation to ensure its ability to provide benefits to society. State fish and wildlife agencies—a primary organizational actor within the conservation community—are a major focal point for needed change. Using a systems framework, this essay describes key leverage points for cultural change for which interventions could result in sustainable culture shifts. Five possible interventions are introduced to stimulate conversation among conservation practitioners seeking to initiate transformational change within their specific cultural contexts. [ABSTRACT FROM AUTHOR]

Edwardsiella ictaluri infects several fish species and protection of the all the susceptible fish hosts from the pathogen using a monovalent vaccine is impossible because the species is composed of host‐based genotypes that are genetic, serological and antigenic heterogenous. Here, immunoinformatic approach was employed to design a cross‐immunogenic chimeric EiCh protein containing multi‐epitopes. The chimeric EiCh protein is composed of 11 B‐cell epitopes and 7 major histocompatibility complex class II epitopes identified from E. ictaluri immunogenic proteins previously reported. The 49.32 kDa recombinant EiCh protein was expressed in vitro in Escherichia coli BL‐21 (DE3) after which inclusion bodies were successfully solubilized and refolded. Ab initio protein modelling revealed secondary and tertiary structures. Secondary structure was confirmed by circular dichroism spectroscopy. Antigenicity of the chimeric EiCh protein was exhibited by strong reactivity with serum from striped catfish and Nile tilapia experimentally infected with E. ictaluri. Furthermore, immunogenicity of the chimeric EiCh protein was investigated in vivo in Nile tilapia juveniles and it was found that the protein could strongly induce production of specific antibodies conferring agglutination activity and partially protected Nile tilapia juveniles with a relative survival percentage (RPS) of 42%. This study explored immunoinformatics as reverse vaccinology approach in vaccine design for aquaculture to manage E. ictaluri infections. [ABSTRACT FROM AUTHOR]

Understanding trade‐offs associated with occupying various aquatic habitats provides a mechanistic understanding of habitat needs that can be used to evaluate the consequences of habitat loss or alteration. We used instream enclosures and field observations to identify how velocity affects the growth rates of four native species in the upper Gila River basin: longfin dace (Agosia chrysogaster) and speckled dace (Rhinichthys osculus), two species of no conservation concern, and loach minnow (Tiaroga cobitis) and spikedace (Meda fulgida), two federally endangered species. Elevated velocity was predicted to increase food delivery through drift or stimulation of benthic primary production. Energetic costs of high‐velocity habitat were predicted to vary with morphology and behaviour and be lowest for speckled dace and loach minnow because they are adapted to occupy interstitial spaces of the substrate in riffles. Spikedace and longfin dace should perform best in moderate velocities, where the trade‐off between exposure to drifting macroinvertebrates outweighs the energetic costs of maintaining position in the water column. Growth rates of loach minnow and speckled dace increased in higher velocities, but contrary to our initial predictions, spikedace growth rates also increased in high‐velocity habitats while longfin dace grew fastest in low‐velocity habitats; similar to the locations these species occupied based on field observations. These results indicate that for spikedace, the increased abundance of drifting macroinvetebrates in high‐velocity habitats outweighs the energy expenditure, but for longfin dace the energetic costs of occupying moderate to high‐velocity habitats outweigh the benefit to increased food availability. Our experiment provides a mechanistic understanding of habitat requirements across species and may inform predictions on how modifications or restoration of riverine ecosystems influence native fish diversity. [ABSTRACT FROM AUTHOR]

Hydrological variations affect habitat characteristics and fish distribution in floodplain lakes. Assessing the contributions of the local community (i.e., LCBD, community uniqueness) and species to overall β diversity (i.e., SCBD, species uniqueness) of fish assemblages is valuable for habitat and species conservation planning, particularly from functional and phylogenetic perspectives. We examined the changes in multifaceted LCBD and SCBD of fish across different hydrological periods in the Poyang Lake, China, and analyzed their responsive mechanisms using regression models, based on which the conservation priorities of habitats and species were evaluated. The findings revealed that taxonomic, functional, and phylogenetic LCBD and SCBD were lowest during the wet season compared to the normal and dry seasons, emphasizing the regulatory effects of hydrological regimes on fish assemblages. Taxonomic and functional LCBD were significantly impacted by the mean abundance of migratory fish, highlighting the importance of specific species combinations on community uniqueness. Taxonomic and functional SCBD exhibited positive correlations primarily with mean abundance, suggesting the potential uniqueness of certain common species. Additionally, we identified the river-lake junction (Hukou station) and natural reserve (Xingzi and Nanjishan stations) with high overall community uniqueness as critical habitats. We also emphasized the necessity for increased conservation efforts for species having high overall species uniqueness during different hydrological periods, including Coilia brachygnathus , Ctenopharyngodon idella , Coilia nasus , Saurogobio dabryi , Hypophthalmichthys molitrix , Megalobrama amblycephala , and Parabramis pekinensis. This research underscores the significance of integrating multiple ecological perspectives to manage biodiversity changes and maintain ecological conservation values effectively. • Hydrological changes regulated the multifaceted community and species uniqueness. • Taxonomic and functional community uniqueness positively responded to biotic factor. • The dominant species displayed high taxonomic and functional species uniqueness. • The multifaceted LCBD and SCBD helps prioritize conserving key areas and species. [ABSTRACT FROM AUTHOR]

Growing ecological and economic impacts of invasive species have heightened the need for new science to inform management that prevents and counteracts their impacts. A persistent challenge is to identify whether removal programs, which range widely in their approach, are successful. Given the variability in dynamic environmental conditions and complex biotic interactions among species, identifying the effectiveness of removal programs intended to lessen nonnative species impacts is inherently difficult. We were interested in whether strategic (i.e. significant coordination and investment) and opportunistic (i.e. temporally periodic and implemented at smaller spatial scales) removal programs result in measurable, and if so, comparable benefits to native fish conservation.We applied a novel dynamic co‐occurrence model to evaluate nonnative fish removal efforts across the Lower Colorado River Basin (USA), while accounting for potential interspecific species interactions and variable hydrologic regimes. We examined the co‐occurrence of two native fishes of conservation concern and two other representative fishes of endemic assemblages, each paired with a nonnative species hypothesized to negatively affect the focal native species.Our model results suggest that both strategic and opportunistic removal programs result in lower extinction probabilities for native fishes (1.2 times greater for strategic programs), especially species of conservation concern, when compared to locations and years not subject to removal. Nonnative species presence mediated native species dynamics, most notably by increasing native species extinction probability during drought years regardless of removal program. Removal efforts resulted in modest changes in extinction probabilities for nonnative fishes, but no measurable effect on colonization dynamics.Synthesis and applications. Both strategic and opportunistic nonnative fish removal programs can help meet recovery goals for native fishes, even over large areas and long after nonnative species are established. Quantifying dynamics of native and nonnative fishes in a multi‐state dynamic co‐occurrence model highlights the collective management value of individual programs at regional scales. Increased evaluation of ongoing nonnative removal programs remains critical to ensuring that management actions are warranted and effective in meeting desired conservation outcomes. [ABSTRACT FROM AUTHOR]

Historical DNA analysis of archival samples has added new dimensions to population genetic studies, enabling spatiotemporal approaches for reconstructing population history and informing conservation management. Here we tested the efficacy of Genotyping-in-Thousands by sequencing (GT-seq) for collecting targeted single nucleotide polymorphism genotypic data from archival scale samples, and applied this approach to a study of kokanee salmon (Oncorhynchus nerka) in Kluane National Park and Reserve (KNPR; Yukon, Canada) that underwent a severe 12-year population decline followed by a rapid rebound. We genotyped archival scales sampled pre-crash and contemporary fin clips collected post-crash, revealing high coverage (> 90% average genotyping across all individuals) and low genotyping error (< 0.01% within-libraries, 0.60% among-libraries) despite the relatively poor quality of recovered DNA. We observed slight decreases in expected heterozygosity, allelic diversity, and effective population size post-crash, but none were significant, suggesting genetic diversity was retained despite the severe demographic contraction. Genotypic data also revealed the genetic distinctiveness of a now extirpated population just outside of KNPR, revealing biodiversity loss at the northern edge of the species distribution. More broadly, we demonstrated GT-seq as a valuable tool for collecting genome-wide data from archival samples to address basic questions in ecology and evolution, and inform applied research in wildlife conservation and fisheries management. [ABSTRACT FROM AUTHOR]

'Coexisting with wildlife' and 'living with wildlife' are commonly used in communication efforts designed to mitigate human-wildlife conflicts. However, there is little information on how the public understands these terms and how their understanding compares to wildlife managers' intended message. In 2019 we surveyed 1,045 Florida residents and 140 Florida Fish and Wildlife Conservation Commission (FWC) officials to examine their understanding of, and preferences for, the terms 'coexisting with wildlife' and 'living with wildlife.' We analyzed data using qualitative and quantitative methods. FWC officials were more likely to interpret both terms as people changing their behavior to mitigate human-wildlife conflicts or tolerating conflicts with wildlife, whereas the public tended to focus on reduced nuisance behavior by wildlife. Wildlife managers should clearly define terms to avoid confusion or miscommunication, which may result in the public not altering their behavior or mistakenly taking actions that exacerbate human-wildlife conflicts such as domesticating wildlife. [ABSTRACT FROM AUTHOR]

1. Designated using a Statutory Instrument in 2008, Lyme Bay marine-protected area (MPA) is the UK's first and largest example of an ambitious, whole-site approach to management, to recover and protect reef biodiversity. The whole-site approach applies consistent management, in this case excluding bottom towed fishing, across the full 206 km² extent of the MPA, thus protecting a mosaic of reef-associated habitats from regular damage, while still allowing less destructive fishing methods, such as static gear, rod and line, and diving. 2. To assess the effectiveness of this management strategy for mobile taxa and the sustainability for those taxa that continue to be targeted, Exploited and Non-Exploited species' populations were compared inside the MPA, relative to open control sites spanning 11 of the 12 years of designation. baited remote underwater video systems (BRUVs) were deployed annually to assess mobile benthic and demersal fauna. 3. Overall, the number of taxa significantly increased in the MPA relative to the open controls while total abundance increased in both treatments. 4. Exploited fish showed increases in number of taxa (430%) and total abundance (370%) inside the MPA over 11 years. 5. Likewise, but to a lesser degree in the open controls, number of taxa of commercially Exploited fish increased over time, potentially showing 'spillover' effects from the MPA. 6. Non-Exploited fish did not show such changes. Regardless of constituting the majority of the fishery value, highly valuable Exploited invertebrates showed no significant changes over time. 7. Synthesis and applications. The Lyme Bay marine-protected area shows importance of protecting a whole site, comprising mosaics of different benthic habitats, through protection of sessile organisms that contribute to essential fish habitats. This Ecosystem Approach to Fisheries Management can benefit and maintain sustainable fisheries and species of conservation importance. [ABSTRACT FROM AUTHOR]

While fisheries provide food and employment for hundreds of millions of people, they also can have significant impact on biodiversity. We explore the potential of area-based fisheries management to simultaneously maintain biodiversity and high levels of sustainable food production. We used two illustrative examples of fisheries that have different gear types, areas, and species to evaluate the trade-off between biodiversity and harvest. We calculate the optimal effort by gear and area that maximizes a weighted objective function of biodiversity and harvest, ranging from 100% of the weight on harvest to 100% on biodiversity. We found for both case studies that the trade-off was highly convex, with win–win solutions allowing for high levels of both fishery harvest and conservation. This is achieved by reducing or eliminating fishing effort that negatively impacts high conservation value species while maintaining fishing effort with gears and in areas where there is low conservation impact. We suggest that, in most fisheries, such situations can be found and that effective area-based management can provide for high levels of biodiversity protection and food production. [ABSTRACT FROM AUTHOR]

Identifying the feeding patterns of large‐bodied predators is necessary to predict their potential effects on food‐web dynamics and to inform species conservation. In contrast to diet information from stomach contents, diet estimates obtained using stable isotopes in blood and muscle can reveal temporal variation in diets.Here, we used an extensive stable isotope dataset and Bayesian stable isotope mixing model to evaluate the trophic role of the Yangtze finless porpoise (Neophocaena asiaeorientalis asiaeorientalis), a critically endangered species distributed in the middle and lower catchments of the Yangtze River. We analysed blood samples from 24 individuals captured during March 2017 in Poyang Lake (which adjoins the Yangtze River), and muscle samples from 8 individuals stranded in the lake over a 1‐year period (2012–2013). We additionally genotyped prey from faecal samples taken from 13 individuals captured in March 2017.We found that as a generalist apex predator, this finless porpoise consumes semi‐migratory and non‐migratory fish prey. However, relative proportions of these two prey resources were different between dietary analyses based on blood samples compared to muscle samples, reflecting recent and longer‐term consumption patterns, respectively.Non‐migratory fish contributed mainly to the diet of predators in the early and middle of March. In contrast, semi‐migratory fish comprised the majority of the prey composition over a more extended period (e.g. 2–3 months), and the difference may be linked to changes in the fish abundance influenced by seasonal factors.Our findings provide insights into the trophic role of this critically imperilled but little studied species, demonstrate how stable isotope analyses can elucidate finless porpoise feeding ecology, and emphasise the importance of semi‐migratory fish to conserving this porpoise population. [ABSTRACT FROM AUTHOR]

Ray species have been globally threatened due to high fishing pressure and habitat loss. In southern Brazil fisheries, despite many ray species are protected by law and usually non-targeted species, they are captured along with commercially important species. However, as in all of Brazil, there is evidence that rays are consumed, that is, there is a demand for meat from these animals, which intensifies the risk of extinction. Marine ethnobiology is an alternative approach to better understand these organisms, considering the traditional empirical knowledge of fishers and local communities. Our objective is to evaluate the knowledge of local residents, fishers, and tourists about the occurrence, distribution, reproduction, and feeding of ray species and also ray consumption among them. We hypothesized that fishers and locals have a deeper ecological knowledge about rays than tourists, and fishers should know more than residents. Individual interviews were conducted for three consecutive days at Armação beach, Florianópolis, Brazil. We asked people about ray biology and ecology based on questionnaires. Each respondent was categorized into three groups: fishers, locals, and tourists; and ranked according to an index of ecological knowledge of rays. The fishers had greater knowledge about rays, followed by residents and tourists. Additionally, fishers and locals consume rays, even the trade is prohibited locally, evidencing the need for legal enforcement. The fishers' knowledge may be essential for management of fish stocks, contributing to sustainable fishing and species conservation. In contrast, the tourists' lack of knowledge evidences the need to raise awareness of these animals. [ABSTRACT FROM AUTHOR]

Bayluscide, a chemical lampricide, is used by government agencies to assess and control invasive Sea Lamprey (Petromyzon marinus) in the Great Lakes basin. The toxicity of Bayluscide to non-target fishes has been previously investigated. However, the potential mortality of fishes and mussels assessed by COSEWIC or listed under Canada's Species at Risk Act as Endangered, Threatened, or Special Concern has not been evaluated based on the factors that dictate species responses in the wild. To assess the potential for mortality, the likelihood that fishes and mussels of conservation concern will be exposed to, and experience toxicity-induced mortality from, granular Bayluscide in the Detroit, St. Clair, Thames, and Sydenham rivers in southwestern Ontario were quantitatively estimated. Simulation models were based on: 1) habitat associations that predispose fishes and mussels species to occur in areas targeted for application; 2) population densities susceptible to exposure; and, 3) the toxicity of the compound, based on: i) assumed Bayluscide concentrations in the environment; ii) taxonomic or habitat match with surrogate species; and, iii) four dose-response relationships, using Sea Lamprey LC50 and LC99.9 concentrations as a benchmark (fishes) or a single point estimate (mussels). Population effects were evaluated by combining estimates of Bayluscideinduced mortality with age-structured models of Eastern Sand Darter (Ammocrypta pellucida; SARA Threatened), Northern Madtom (Noturus stigmosus; SARA Endangered), Channel Darter (Percina copelandi; Lake Erie DU, SARA Endangered), and Ichthyomyzon spp. In most cases, simulated applications resulted in no or low mortality of fishes and mussels. However, in some cases (≤ 5%), mortality of ones to tens of fishes and potentially hundreds of freshwater mussels and Silver Lamprey (Ichthyomyzon unicuspis) or Northern Brook Lamprey (I. fossor) occurred following a single application cycle. Based on a model in which recovery from Bayluscide effects does not occur, the 50-100 year effect of repeated Bayluscide application could reduce abundance by as much as 100% from baseline for some species (Northern Madtom, Ichthyomyzon spp.) or up to 90% for others (Eastern Sand Darter) if populations are small and applications occurred annually but would be less severe if populations are large. Estimated mortality varied with the frequency and size of applications but relationships were non-linear. Several uncertainties were identified including: 1) environmentally relevant concentrations of Bayluscide; 2) species-specific Bayluscide toxicity and appropriateness of surrogates; 3) incidence and effect of avoidance behavior; 4) occurrence, density, and habitat associations based on a limited number of field studies; and, 5) unknown population abundance and trajectory for most species of conservation concern. Results indicate that in some cases, Bayluscide may result in mortality and population effects for species of conservation concern but mortality may be mitigated by several factors associated with the application cycle. [ABSTRACT FROM AUTHOR]

Bayluscide, a chemical lampricide, is used by government agencies in the Great Lakes basin to assess Sea Lamprey (Petromyzon marinus) as part of bi-national efforts to control the species. The use of granular Bayluscide has been highly successful in identifying and suppressing Sea Lamprey populations. However, the ecological risk of Bayluscide for fishes and mussels listed under Canada's Species at Risk Act and other species of conservation concern is not well understood. This document: 1) identifies potential pathways (direct, indirect) and mechanisms (physiological, non-physiological) by which the application of granular Bayluscide may influence fishes and mussels of conservation concern; 2) evaluates the relative ecological risk of applications based on four metrics (spatial distribution, application intensity, habitat associations that predispose species to exposure, toxicity); 3) identifies mitigation measures that may reduce potential impacts to non-target species; and, 4) identifies uncertainties needed to refine risk estimates. Spatial analyses indicated that between 2011 and 2017, Bayluscide applications occurred within the distribution of 21 fish and 15 mussel species of conservation concern including areas identified as critical habitat for 16 species (6 fishes, 10 mussels). For fishes, relative risk was greatest for native lampreys (Silver Lamprey [Ichthyomyzon unicuspis] and Northern Brook Lamprey [Ichthyomyzon fossor]) followed by Lake Sturgeon (Acipenser fulvescens) and Northern Madtom (Noturus stigmosus). Native lampreys exhibited high relative risk given habitat preferences and the toxicity of Bayluscide to those species. Northern Madtom ranked highly due to exposure (spatial and temporal patterns of application) and toxicity. Lake Sturgeon ranked highly due to exposure, though results were not directly comparable with other species due to assessment methods. For mussels, relative risk was greatest for Salamander Mussel (Simpsonaias ambigua), Threehorn Wartyback (Obliquaria reflexa), and Hickorynut (Obovaria olivaria). Salamander Mussel and Threehorn Wartyback ranked highly due to exposure and toxicity. A high risk ranking for Hickorynut occurred due to exposure and habitat preference. Mitigation measures to reduce the ecological consequences of Bayluscide applications are numerous and include modifying the frequency and timing of treatments, decreasing the size of application sites, and avoiding areas near critical habitat. However, the effect of potential mitigation measures should be rigorously tested to ensure that desired outcomes for species of conservation concern are realized while avoiding unintended consequences. Lastly, as reduced control effectiveness of Sea Lamprey would have undesirable effects on species of conservation concern susceptible to parasitism by Sea Lamprey (e.g., Lake Sturgeon), optimization measures may be warranted to account for such trade-offs. [ABSTRACT FROM AUTHOR]

The sustainable mitigation of human–wildlife conflicts has become a major societal and environmental challenge globally. Among these conflicts, large marine predators feeding on fisheries catches, a behaviour termed "depredation," has emerged concomitantly with the expansion of the world's fisheries. Depredation poses threats to both the socio‐economic viability of fisheries and species conservation, stressing the need for mitigation. This review synthesizes the extent and socio‐ecological impacts of depredation by sharks and marine mammals across the world, and the various approaches used to minimize it. Depredation was reported in 214 fisheries between 1979 and 2019 (70% post‐2000) and affected fleets from 44 countries, in all sectors (commercial, artisanal and recreational), and in all major fishing techniques (nets, traps and hook‐and‐lines). A total of 68 predator species were involved in depredation (20 odontocetes, 21 pinnipeds and 27 sharks), and most (73%) were subject to either by‐catch and/or retaliatory killing from fishers when interacting with gear. Impacts on fishers were primarily associated with catch losses and gear damage but often lacked assessments. Deterrence was a major mitigation approach but also the least effective. Gear modifications or behavioural adaptation by fishers were more promising. This review highlights the need for improved monitoring, and interdisciplinary and integrated research to quantify the determinants and impacts of depredation in the socio‐ecological dimension. More importantly, as the conflict is likely to escalate, efforts directed towards changing perceptions and integrating knowledge through adaptive co‐management are raised as key directions towards coexistence between fisheries and large marine predators. [ABSTRACT FROM AUTHOR]

The document provides a list of upcoming fisheries-related conferences and meetings taking place between January and March 2024. The events are held in various locations across the United States and Canada, covering topics such as aquaculture, fish and wildlife conservation, and ecosystem management. The conferences offer opportunities for professionals and researchers in the field to network, share knowledge, and discuss the latest developments in fisheries science and management. [Extracted from the article]