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In order to develop a method that apply sampling survey data randomly obtained at fishing ports to fish stock assessments, based on fish landing surveys conducted at fishing ports in the northern South China Sea (SCS), 19 Threadfin porgy (Evynnis cardinalis) catch per unit effort (CPUE) datasets were collected for fishing vessels with different gear types and engine powers and incorporated into surplus production models. Considering only the fitting performance, the Schaefer model had the best overall goodness of fit, followed by the Fox, CYP, W–H, and Schnute models. Among fishing vessels with different gears and engine powers, the data were best fitted for single-trawl vessels powered by 301–400-kW engines and for gillnet vessels powered by > 200-kW engines. Eight model expressions were superior and selected for subsequent analyses based on their goodness of fit and relative residuals. The Kobe plot analysis results showed an optimistic fish stock status when using the four model expressions, required more caution when using three model expressions and output pessimistic estimations using one model expression. Considering the incomplete information acquired, a compromising decision-making method was used to derive a 2017 northern SCS E. cardinalis total allowed catch (TAC) of 44,691.21 t. The different conclusions drawn from estimations using CPUEs reflect variable exploitation and utilization fish stock statuses among fishing vessels with different gears and engine powers. Hence, the fishing operations were grouped according to their CPUE relationship, and recommendations regarding optimum fishing efforts were assigned to the groups following a fundamental principle: to improve fishery TAC management, fishing efforts should be reduced if the fish stock assessment is pessimistic and maintained if the assessment is optimistic. This study providing a feasible technical method for the TAC management of China's offshore fisheries.

Climate change and industrial fishing have profound effects on marine ecosystems. Numerical models that capture key features of fish biomass dynamics and its interaction with fishing can help assess the biogeochemical and socio-economic consequences of these impacts. However, these models have significant biases and do not include many processes known to be relevant. Here we describe an updated version of the BiOeconomic mArine Trophic Size-spectrum (BOATS) model for global fish and fisheries studies. The model incorporates new ecological and economic features designed to ameliorate prior biases. Recent improvements include reduction of fish growth rates in iron-limited high-nutrient low-chlorophyll regions, and the ability to simulate fisheries management. Novel features described here include a separation of pelagic and demersal fish communities to provide an expanded representation of ecological diversity, and spatially variable fishing costs and catchability for more realistic fishing effort dynamics. We also introduce a new set of observational diagnostics designed to evaluate the model beyond the boundary of large marine ecosystems. Following a multi-step parameter selection, the updated BOATSv2 model shows comparable performance to the original model in coastal ecosystems, accurately simulating catch, biomass and fishing effort. The revised model provides a markedly improved representation of fisheries in the High Seas, largely correcting the biases of the original version, including excessive high-sea catches and too rapid deepening of fishing effort over time. The updated model code is available for simulating both historical and future scenarios. [ABSTRACT FROM AUTHOR]

Ghosh, S.; Anju, P.; Pattanayak, R., and Sahu, N.C., 2024. Fisheries and aquaculture in wetland ecosystems: A review of benefits, risks, and future prospects in India. Journal of Coastal Research, 40(3), 598–612. Charlotte (North Carolina), ISSN 0749-0208. Globally, wetland ecosystems are vital for supporting biodiversity and provide numerous ecosystem services, with fisheries playing a pivotal role. Wetlands are essential nurseries for fish, supporting fisheries that contribute significantly to food security and livelihoods. Wetlands offer a consistent supply of water, which can be well utilized for fisheries and aquaculture. Groundwater recharge from wetlands is crucial for irrigation, drinking water, and other uses. Additionally, wetlands control water movement, aiding in the reduction of floods and droughts. They also serve as carbon sinks and play a crucial role in mitigating climate change. However, wetlands face multiple risks, including habitat destruction due to urbanization and agricultural expansion, water pollution, overfishing, and invasive species. Climate change exacerbates these threats, altering wetland habitats and fish behavior. Sustainable wetland fisheries management is essential to mitigate these risks, emphasizing the need for community-based approaches, habitat restoration, and the development of resilient fish populations. The future prospects of wetland fisheries lie in integrated conservation strategies that balance the ecological significance of wetlands with the socioeconomic benefits to humans. Incorporating traditional ecological knowledge, scientific research, and policy interventions will be key to safeguarding these ecosystems and ensuring sustainable fisheries and aquaculture. In the context of the expanding fisheries and aquaculture industries, this study addresses the significance, risks, and future prospects of wetlands in India. [ABSTRACT FROM AUTHOR]

The United Nations Fish Stocks Agreement requires states to recognise the special requirements of developing countries and to ensure that conservation and management measures do not place a disproportionate burden on developing countries. The aim of this article is to assess what policy arrangements are required to reduce the identified disproportionate burden. We developed a policy pathway that would allow members of tuna regional fisheries management organisations (tRFMOs) to strengthen their efforts to meet their duty to share conservation burdens more equitably. This pathway consists of policy options that were developed by using policy analysis, which is an innovative approach that provides actionable outcomes that can be used by tRFMO member states. Despite the global attention to reducing disproportionate conservation burdens, developing states are still suffering. The results of this article provide novel and timely policy options that have the potential to reduce the conservation burden carried by developing states. [ABSTRACT FROM AUTHOR]

Despite continued calls for the application of ecosystem‐based fisheries management, tactical fisheries management continues to be heavily reliant on single‐species stock assessments. These stock assessments rarely quantitatively integrate the effects of ecosystem processes on fish stock productivity. This lack of integration is ultimately driven by the complexity of interactions between populations, ecosystems and fisheries, which produces uncertainty when defining which processes to include and how to include them. Models developed using a structured hypothesis testing framework would allow formalizing uncertainties while underscoring the importance of incorporating different population and ecosystem processes to explain non‐stationary stock productivity. Here, we develop a conceptual framework for extending and comparing population dynamics models of increasing complexity. We illustrate the utility of the framework by investigating the population and ecosystem processes that most likely affected the differential recovery of two flatfish populations (American plaice and yellowtail flounder) on the Newfoundland Grand Banks over the past three decades. We found that yellowtail flounder population dynamics were primarily driven by recruitment variability, which was negatively affected by warmer climatological conditions, as indicated by an integrated regional climate index. Meanwhile, American plaice population dynamics were affected by a combination of temporal variability in recruitment and natural mortality, where natural mortality increased during colder than average conditions. By exploring hypotheses about the effects of population and ecosystem processes on population dynamics, this modelling framework will improve understanding about the drivers of shifts in population productivity while serving as a transparent and robust approach to support ecosystem‐based fisheries management. [ABSTRACT FROM AUTHOR]

Natural ecological communities exhibit complex mixtures of interspecific biological interactions, which makes finding optimal yet sustainable exploitation rates challenging. Most fisheries management advice is at present based on applying the Maximum Sustainable Yield (MSY) target to each species in a community by modelling it as if it was a monoculture. Such application of single‐species MSY policies to strongly interacting populations can result in tragic overexploitation. However, the idea of 'maximising the yield from each species separately' can be extended to take into account species interactions. This leads to a form of Nash Equilibrium, where the yields of each species are simultaneously maximised. Here we present 'nash', an R package that streamlines the computation of Nash equilibrium reference points for fisheries and other systems represented by a user‐defined multispecies or ecosystem model. We present two real‐world fisheries management applications alongside performance benchmarks. Satisfactory search results are shown across models with an approximate factor 7 increase in performance when compared to the expensive round‐robbing sequential optimisation algorithms used by other authors in the literature. We believe that the nash package can play an instrumental role in fully implementing ecosystem‐based management policies worldwide. [ABSTRACT FROM AUTHOR]

Despite progress in the management of assessed fish populations, many countries lag behind international commitments to restore overexploited stocks to healthy abundances. Here we use a mixed‐methods positive deviance approach, also known as 'bright spot' analysis, to understand what drives the successful governance of exploited species by learning from positive outliers, or 'deviants'. We use Canada as a case study, identifying factors driving the abundance of 230 commercially exploited fish and invertebrate populations, of which only 28% were classified at healthy abundance in 2022. We first applied a generalized linear model to test how diverse socio‐ecological fishery attributes relate to stock health. We found healthier stocks are positively and significantly correlated with certain management regions, more selective gears, eco‐certification, and high fishery value. Counterintuitively, healthier stocks were also associated with high inherent fishing vulnerability and the absence of reference points. We then used fishery expert surveys and interviews to investigate the social and institutional characteristics of stocks healthier than expected, given their circumstances. We found that fisheries targeting these positive outliers have lower conflict among users, balanced stakeholder involvement in data collection and decision‐making, and improved accounting of mortality sources. Lessons from these positive deviants can be applied to improve underperforming management systems that are struggling to reverse overexploitation in Canada and elsewhere. More generally, we suggest that a positive deviance approach, already used in public health, could be a promising tool to learn about successful fisheries management interventions, and the diverse actors responsible for ensuring these interventions are successful. [ABSTRACT FROM AUTHOR]

Fishers have intensively used drifting fish aggregating devices (DFADs) over the last three decades to facilitate their catch of tropical tunas. DFADs increase purse‐seine efficiency, potentially increasing tuna fishing mortality. They could also have impacts on tuna natural mortality and reproductive potential, and assessing the consequences of their presence at sea on tuna populations is a challenge. The use of DFADs results in a major increase in the number of floating objects, which are spatially heterogeneous at sea. To date, no converging scientific results exist regarding the effects of DFADs on the large‐scale movements and behaviour of tuna, mainly due to the difficulty of disentangling the respective roles of DFADs and environmental factors. Some biological indices show that tuna condition is lower when associated to a floating object than in a free‐swimming school. However, it is not clear whether this is the cause or the consequence of the association nor if it has long‐term effects on individuals' fitness. Further scientific progress requires (i) the collection of time series of indicators to monitor habitat change, individual behaviour, individual fitness, and population dynamics and (ii) experimental studies to identify the underlying behavioural and biological processes involved in associative behaviour. The extent of the modification of the surface habitat by the massive deployment of DFADs and the current uncertainty of the possible long‐term consequences on the individual fitness and dynamics of tuna populations argue for the need for increased awareness of this issue by Regional Fisheries Management Organisations regulating tuna fishing. [ABSTRACT FROM AUTHOR]

There exists an extensive, diverse, and robust evidence base to support complex decisions that address the planetary biodiversity crisis. However, it is generally not sought or used by environmental decision-makers, who instead draw on intuition, experience, or opinion to inform important decisions. Thus, there is a need to examine evidence exchange processes in wildlife management to understand the multiple inputs to decisions. Here, we adopt a novel approach, fuzzy cognitive mapping (FCM), to examine perceptions of individuals from Indigenous and Western governments on the reliability of evidence which may influence freshwater fisheries management decisions in British Columbia, Canada. We facilitated four FCM workshops participants representing Indigenous or Western regulatory/governance groups of fisheries managers. Our results show that flows of evidence to decision-makers occur within a relatively closed governance network, constrained to the few well-connected decision-making organizations (i.e., wildlife management agencies) and their close partners. This implies that increased collaboration (i.e., knowledge co-production) and engagement (i.e., knowledge brokerage) with wildlife managers and decision-makers are needed to produce actionable evidence and increase evidence exchange. [ABSTRACT FROM AUTHOR]

The role of vegetated habitats such as seagrass and macroalgal beds as nurseries is essential for the survival of larval and juvenile fish, although quantitative evaluation of the contribution of these habitats to nursery function is limited. Moreover, growth–survival relationships of larvae and juveniles associated with vegetated habitats have rarely been examined. To quantitatively and qualitatively evaluate the processes affecting juvenile survival in vegetated habitats, we investigated whether there is a correlation between the degree of selection for bigger and faster‐growing fish and mortality rates for three cohorts by birth date of post‐settlement black rockfish (Sebastes cheni) in a macroalgal bed. We also analyzed relationships between growth rate and experienced temperature by age class to examine the effects of temperature on growth. The latest cohort, which grew under lower vegetation coverage due to a seasonal increase in water temperature, showed higher mortality with evidence of strong selection for survival of bigger and faster‐growing fish. The growth–temperature relationships showed that positive effects of temperature on growth weakened after settlement. Therefore, we suggest that macroalgal coverage has a critical role in controlling the growth–mortality relationship of post‐settlement S. cheni. Furthermore, the negative effects of high temperature on juvenile survival through loss of vegetation may be greater than the positive effects on juvenile growth. These findings would contribute to the management of fisheries resources by increasing the understanding of relationships between survival mechanisms in fish early life stages and vegetation phenology of their habitat under the increasing effects of global warming. [ABSTRACT FROM AUTHOR]

The global population consumes more seafood from aquaculture today than from capture fisheries and although the aquaculture industry continues to grow, both seafood sectors will continue to be important to the global food supply into the future. As farming continues to expand into ocean systems, understanding how wild populations and fisheries will interact with farms will be increasingly important to informing sustainable ocean planning and management. Using a spatially explicit population and fishing model we simulate several impacts from ocean aquaculture (i.e., aggregation, protection from fishing, and impacts on fitness) to evaluate the mechanisms underlying interactions between aquaculture, wild populations and fisheries. We find that aggregation of species to farms can increase the benefits of protection from fishing that a farm provides and can have greater impacts on more mobile species. Splitting total farm area into smaller farms can benefit fishery catches, whereas larger farms can provide greater ecological benefits through conservation of wild populations. Our results provide clear lessons on how to design and co-manage expanding ocean aquaculture along with wild capture ecosystem management to benefit fisheries or conservation objectives. [ABSTRACT FROM AUTHOR]

Cyphocharax magdalenae, a Colombian freshwater fish species, plays a vital role in nutrients distribution and serves as a significant food source for other fish species and local fishing communities. Considered a short-distance migratory species, C. magdalenae populations face substantial extinction risk due to human activities impacting their habitats. To address the lack of knowledge on genetic diversity and population structure, this study used next-generation sequencing technology to develop species-specific microsatellite loci and conducted a population genetics analysis of C. magdalenae in the middle and lower sections of the Cauca River, Colombia. Out of 30 pairs of microsatellite primers evaluated in 324 individuals, 14 loci were found to be polymorphic, at linkage equilibrium and, in at least one population, their genotypic frequencies were in Hardy-Weinberg equilibrium. Results showed high genetic diversity levels compared to other neotropical Characiformes, with inbreeding coefficients similar to those reported for phylogenetically related species. Moreover, C. magdalenae exhibits seasonal population structure (rainy-dry) consisting of two genetic stocks showing bottleneck signals and high effective population sizes. This information is essential for understanding the current species genetics and developing future management programs for this fishery resource. [ABSTRACT FROM AUTHOR]

Fish dietary niche is a core focus, and it reflects the diversity of resources, habitats, or environments occupied by a species. However, whether geographic segregation among different populations triggers dietary diversification and concomitant fish niche shift remains unknown. In the present study, we selected the Black Amur bream (Megalobrama terminalis) is a migratory fish species that plays an important role in the material transfer and energy cycling of river ecosystems, inhabiting southern China drainage with multiple geographic populations. Here, we utilized the combined analyses of 18S rDNA high‐throughput sequencing in fish gut contents and fatty acid (FA) in muscle tissues to evaluate potential spatial patterns of habitat and resource use for M. terminalis in three rivers of southern China. Our results showed that prey items of the Xijiang (XR) population (Pearl River) exhibited the highest species diversity and richness among the three geographic populations. Moreover, diet composition of M. terminalis was affected by spatial differences associated with geographic segregation. Analyses of FA biomarkers indicated that the highest levels of C16:0, C18:3n‐3, and C18:2n‐6c were found in Wanquan (WS) population (Wanquan River). The XR population exhibited a distinct FA profile characterized by higher amounts of arachidonic acid (ARA) and docosahexaenoic acid (DHA). The Moyang (MY) population (Moyang River) acted as the linkage between WS and XR populations and consisted of middle levels of saturated FAs (SFAs) and polyunsaturated FAs (PUFAs). The XR population displayed a greater FA niche width compared with WS population. Furthermore, we observed a close positive relationship between the niche width and α‐diversity indices of dietary resources for FA proflies. Our study provides valued information to develop different conservation strategies among different populations and improve fisheries management for M. terminalis and other endemic species in local rivers. [ABSTRACT FROM AUTHOR]

Climate change is altering the distribution and abundance of marine species, especially in Arctic and sub‐Arctic regions. In the eastern Bering Sea, home of the world's largest run of sockeye salmon (Oncorhynchus nerka), juvenile sockeye salmon abundance has increased and their migration path shifted north with warming, 2002–2018. The reasons for these changes are poorly understood. For these sockeye salmon, we quantify environmental and biological covariate effects within spatio‐temporal species distribution models. Spatio‐temporally, with respect to juvenile sockeye salmon densities: (1) sea surface temperature had a nonlinear effect, (2) large copepod, Calanus, a minor prey item, had no effect, (3) age‐0 pollock (Gadus chalcogrammus), a major prey item during warm years, had a positive linear effect, and (4) juvenile pink salmon (O. gorbuscha) had a positive linear effect. Temporally, annual biomass of juvenile sockeye salmon was nonlinearly related to sea temperature and positively related to age‐0 pollock and juvenile pink salmon abundance. Results indicate that sockeye salmon distributed with and increased in abundance with increases in prey, and reached a threshold for optimal temperatures in the eastern Bering Sea. Changes in population dynamics and distribution of sockeye salmon in response to environmental variability have potential implications for projecting specific future food securities and management of fisheries in Arctic waters. [ABSTRACT FROM AUTHOR]

The southern red snapper, Lutjanus purpureus, is one of the primary fishery resources of the Amazon continental shelf. Due to the demand for specimens of less than 900 g in weight, increased fishing effort focusing on this size class has led to a drastic decrease in catches. The present study was based on the analysis of cellular structures in the female gonads (formation of oocytes and other reproductive tissues) to identify reproductive processes and evaluate the effectiveness of current fishery management practices. The presence of postovulatory follicles (POFs) peaked in April, which was interpreted as a period of intense spawning. In addition to POFs, hydrated oocytes peaked in July, indicating either reproductive continuity or a second peak, based on the presence of atretic oocytes and atresia. Given that the local snapper fishery preferentially targets very young individuals, an extension of the closed season from March to July would be recommendable to guarantee the reproductive potential of the spawning stock. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the growth, mortality parameters, and exploitation rate of Pontic shad, Alosa immaculata Benett, 1835, in the Danube River, Romania (km 169–197). The sampling collection started with the first signs of Pontic shad migration, on 4 March 2023, and continued weekly until the beginning of June 2023, when the last specimens were caught in the nets. The estimation of the growth, mortality parameters, and exploitation rate was done in FiSAT (FAO-ICLARM Stock Assessment Tools). The von Bertalanffy growth equation was estimated at L∞ = 36.75 cm, the growth coefficient was k = 0.68 year−1, and the theoretical initial age was t0 = −0.67 year−1. The total mortality rate (Z) estimated was 2.76 year−1, with a natural mortality rate (M) and fishing mortality rate (F) of 0.89 year−1 and 1.87 year−1, respectively. The Z/k ratio was found to be 4.11 and the exploitation rate (E) was estimated at 0.68 year−1, indicating the overexploitation of Alosa immaculata stocks. In conclusion, this study provides valuable insights into the population dynamics of Pontic shad in the Danube River, Romania. The assessments of the growth parameters, mortality rates, and exploitation rates highlight a level of overexploitation of Alosa immaculata stocks. These findings underscore the importance of applying effective fishery management strategies to ensure the sustainability and conservation of this valuable fish species in the Danube River ecosystem. [ABSTRACT FROM AUTHOR]

Japanese anchovy (Engraulis japonicus) is a small pelagic fish with commercial and ecological importance. In spite of its importance, in recent years, specific research on anchovy in the Shandong Peninsula area has been relatively scarce and outdated. This study aims to estimate the age and growth characteristics of anchovy through year-round seasonal sampling from 2016 to 2017, utilizing length–frequency and otolith microstructure analysis. The higher coastal abundance and larger size observed in the spring and summer suggest a potential peak spawning period for anchovies dominated by larger-sized individuals. Based on otolith analysis, anchovies range in age from 0 to 4 years, with a limited presence at age 0 and dominance in the age-1 group. The length–weight relationship (LWR) equation shows hyper-allometric growth for each season, with a mean relative condition factor (Kn) of 1.025 ± 0.005, indicating good health. Additionally, the von Bertalanffy growth equation of can be expressed as Lt = 154.40 [1 − e−0.604 (t + 0.965)], suggesting a medium growth rate (K = 0.604). These findings contribute to the understanding of anchovy age and growth patterns, emphasizing the continuous need for research and monitoring to support rational and sustainable fisheries management and conservation efforts. [ABSTRACT FROM AUTHOR]

The crab fishery of the genus Callinectes is one of the most important fisheries in Mexico. Sonora and Sinaloa are the states on the eastern coast of the Gulf of California, the mainland coast. Sinaloa encompasses the greatest production in Mexico of these species, in particular the Bahía Santa Maria La Reforma (BSMR), supplying the most important catches. A mandatory administrative document for the fishery is the Management Plan of Crab. One of the main weaknesses found in it for Sonora and Sinaloa is the lack of fishery assessment in both states. For this reason, a size-structured method called CASA (Catch-at-Size Analysis) was applied in the BSMR, in the seasons 2000, 2011, and 2014, to C. bellicosus. The first catch size (CW50%) estimated for females was 97.5, 102.5, and 100 mm, while in males, it was estimated at 117.5, 107.5, and 102.5 mm. In the specific case of fishing mortality (F), the algorithm allowed us to find that in the larger sizes, a greater fishing pressure is applied for both females and males, yielding a weighted exploitation rate of 0.047 (2000), 0.119 (2011), and 0.426 (2014) for females and 0.045 (2000), 0.295 (2011), and 0.132 (2014) for males, all below 50% (E = 0.50). The crab C. bellicosus in BSMR is not at risk of overexploitation. [ABSTRACT FROM AUTHOR]

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

The International Council for the Exploration of the Sea (ICES) typically provides advice on fishing opportunities on a stock-by-stock basis. Nevertheless, levels of total allowable catch (TAC) are sometimes set for a collection of stocks and species (i.e. a common TAC). An explicit expectation of these is that landings will scale with ICES advice, especially when ICES advice is used to calculate the common TAC. This expectation is tested for skates and rays in the Northeast Atlantic, spanning 26 stocks, 8 species, and 3 ecoregions. Using ICES landings and ICES advice data from 2016 to 2022, we show that landings of several stocks and species have overshot their respective ICES advice, whereas others have undershot. Specifically, some stocks of blonde ray (Raja brachyura) in North Sea and Celtic Seas ecoregions are being landed at a rate that often exceeds double its ICES advice. By collating species based on their ICES assessment category and life-history traits, we find that those considered data-poor and potentially most vulnerable to fishing are consistently landed at higher-than-expected rates in the Celtic Seas. This study questions the appropriateness of a common TAC for skates and rays and calls for shifts towards the use of single-stock catch allocations and the application of advanced stock assessment methodologies. [ABSTRACT FROM AUTHOR]

European sea bass (Dicentrarchus labrax [Linnaeus, 1758]) is a euryhaline marine migrant fish highly valuable for fisheries and aquaculture. Although juveniles are known to use estuaries and occasionally move to freshwater environments, these freshwater incursions had not been reported for adults. Recently, this behavior was observed in the Tagus River (Portugal) for adults occurring up to 150 km from the river mouth, about 80 km upstream from the tidal influence, suggesting the existence of a freshwater contingent. Fisheries management of sea bass should consider the putative existence of a freshwater contingent. [ABSTRACT FROM AUTHOR]

Previous studies have used theoretical general equilibrium or empirical computable general equilibrium models to analyze the economic and welfare effects of fishery rationalization, adopting a simplistic assumption regarding factor mobility. This study relaxes the simplistic assumption and considers more possibilities of mobility when assessing the effects of rationalization using a computable general equilibrium model for the Gulf of Alaska groundfish trawl fishery. Results demonstrate that the effects of rationalization vary significantly across different factor mobility assumptions, suggesting that the effects computed based on the simplistic assumption could mislead fishery managers. [ABSTRACT FROM AUTHOR]

Predator–prey interactions in time and space determine stock productivity, making them an important consideration when managing marine resources, rebuilding stocks or considering reopening a fishery.We analysed fine‐scale diet data from surveys conducted in 2009–2010 and 2018–2019 in three fjords in northern Norway with geostatistical models investigating how predation varied in space, time and between predator species. Our focus prey species was northern shrimp (Pandalus borealis), valuable both as a commercial resource and a major food source for other important species like Atlantic cod (Gadus morhua).Diet composition of fish predators differed clearly between fjords. While predator species and size were good predictors of shrimp predation, the relationships with bathymetry, prey density and geospatial variables were complex.Our study indicates that predation of forage species, such as shrimp, varies spatially in heterogenous fjord ecosystems. Shrimp consumption was not highest in the fjord with highest predator density, indicating a higher dependency of cod on shrimp in specific areas.Realized predation is a complex combination of predator and prey densities and predator ecology that differed in each of the three fjords.Synthesis and applications. Ignoring spatial variations in predator–prey interactions may lead to an inaccurate perception of stock productivity, suboptimal management and possibly unsustainable management targets. We recommend spatially explicit assessment and management for fish stocks where predator–prey interactions vary substantially in space, such as fjords and reefs. [ABSTRACT FROM AUTHOR]

Canadian fisheries management has embraced the precautionary approach and the incorporation of ecosystem information into decision-making processes. Accurate estimation of fish stock biomass is crucial for ensuring sustainable exploitation of marine resources. Spatio-temporal models can provide improved indices of biomass as they capture spatial and temporal correlations in data and can account for environmental factors influencing biomass distributions. In this study, we developed a spatio-temporal generalized additive model (st-GAM) to investigate the relationships between bottom temperature, depth, and the biomass of three key fished species on The Grand Banks: snow crab (Chionoecetes opilio), yellowtail flounder (Limanda ferruginea), and Atlantic cod (Gadus morhua). Our findings revealed changes in the centre of gravity of Atlantic cod that could be related to a northern shift of the species within the Grand Banks or to a faster recovery of the 2J3KL stock. Atlantic cod also displayed hyperaggregation behaviour with the species showing a continuous distribution over the Grand Banks when biomass is high. These findings suggest a joint stock assessment between the 2J3KL and 3NO stocks would be advisable. However, barriers may need to be addressed to achieve collaboration between the two distinct regulatory bodies (i.e., DFO and NAFO) in charge of managing the stocks. Snow crab and yellowtail flounder centres of gravity have remained relatively constant over time. We also estimated novel indices of biomass, informed by environmental factors. Our study represents a step towards ecosystem-based fisheries management for the highly dynamic Grand Banks. [ABSTRACT FROM AUTHOR]

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

The proportion of mature fish at length is one of the most important population attributes when evaluating reproductive potential for fish stock assessment purposes. Bias in maturity ogive parameters can lead to fishery management decisions based on misspecified biological reference points. These parameters can vary spatially and temporally, and this variability should be understood and included in the assessment models. However, integrating this variability becomes challenging when specific spatial-dependent ogives cannot be used in the stock assessment model. Hence, this study proposes a novel use of a multivariate response Bayesian regression model, employing an integrated nested Laplace approximation to estimate a single global maturity ogive using data from various spatial areas. This model explicitly accounts for differences in the sampling process and combines information from different areas to estimate shared maturity ogive parameters using joint-likelihood procedures. The model is applied to the European hake stock in ICES (International Council for the Exploration of the Sea) Divisions 27.8.c and 27.9.a, serving as a practical guide. In this model, we have considered different predictors to handle the relationship between the probability of being mature and the length and year covariates. Our results suggest that the logistic formulation correctly captures the relationship between the probability of being mature and length. For year variability, including a year factor covariate or year random effect in the predictor model produces similar values of goodness of fit measures. [ABSTRACT FROM AUTHOR]

Fish that undertake juvenile migration pass through habitats that vary in mortality risk. The ability to identify regions of persistently low survival would improve fishery management. We conducted a field study combined with predictive modeling of survival in downstream migrating juvenile sea lamprey using a new micro-acoustic telemetry tag designed for implantation into small, slender-bodied fishes. Detection data were collected from eight receivers placed across a coastal riverine–wetland–lake complex. Juvenile sea lamprey initiated downstream movement near nautical twilight, stopped frequently, and were more likely to move during high river discharge. Estimated survival was highest in the riverine reach, declined through the river–wetland complex, and dropped precipitously in the drowned rivermouth lake. However, the high transmission rate and resulting short battery life of the microtransmitters (as configured) likely resulted in missed detections in the lower reaches. Simulation analyses suggested survival estimation could be improved by increasing the number of tagged lamprey and staggering release locations. We offer practical recommendations for the use of this new transmitter in field studies with small anguilliform fish. [ABSTRACT FROM AUTHOR]

This study examines the effect of common bottlenose dolphins Tursiops truncatus on the purse-seine fishery for small pelagic fishes in the Mediterranean Sea and the economic consequences thereof. The investigation focused on the fleet registered at the port of Al Hoceima, Morocco, and used information collected from on-board observations and a semi-structured questionnaire with fishermen and ship-owners. A total of 121 dolphins were captured as bycatch during 48 fishing trips, with a mortality rate of 0.23 dolphins per fishing trip. In terms of damage to the fishing gear, the number of observed holes varied between 28 and 230 per net per incident. Though some tears were large, most were <35 cm in height. The cost of repairing the holes in the nets caused by these interactions was estimated at US$179.52 per mending event. The level of interaction between common bottlenose dolphins and the purse-seine fishery targeting small pelagic fishes is a challenge for both fishery management and dolphin conservation. [ABSTRACT FROM AUTHOR]

Poverty reduction and fisheries management in Madagascar have converged on the marine seascape, directed at an unassuming creature: the sea cucumber. In southwestern Madagascar, the enclosure of what was once a common pool resource has led to violence and new gendered seascapes. This form of blue grabbing, promoted by private companies and NGOs alike as an avenue to achieve conservation and develop coastal economies, has fundamentally restructured property relations and who benefits from marine resources. Sea cucumber pens, established in some areas with the input of a narrow local elite and guarded at times by the police have become high risk environments where fishers report injury and death, pointing to important questions about the metrics and means of sustainable production in the marine realm, and whose interests and access to marine resources are prioritized. [ABSTRACT FROM AUTHOR]

Estimates of recreational fishing effort and catch are needed to inform fisheries management, but such estimates can be challenging to obtain. We combined a zig‐zag line transect survey of buoys, a fisheries enforcement survey and a drone survey to estimate recreational effort in the open‐access trap fishery for signal crayfish (Pacifastacus leniusculus) in the sixth largest lake in Europe, Lake Vättern, Sweden. Using supporting variables such as size of nearby ports and bathymetry, our model‐assisted estimate of total effort was 6400 (±4300 CI) buoys during the three‐weekend season. Using the frequency of buoys to traps as a constant, the total number of crayfish traps was estimated to be 25,500 (±17,000 CI). The sampling design and methods presented are useful for ecologists and resource managers to design future multi‐source surveys of recreational trap fishing effort. [ABSTRACT FROM AUTHOR]

Movements of common fish species in large lakes that are inadequately known is challenging for fisheries management. Pikeperch (Sander lucioperca) (n = 478; mean length = 42.1 cm; SD = 7.0), bream (Abramis brama) (n = 775; mean length = 31.1 cm; SD = 5.3) and roach (Rutilus rutilus) (n = 939; mean length = 21.4 cm; SD = 2.0) were marked with individual T‐anchor tags to investigate movements in Lake Vesijärvi, a large lake situated in southern Finland consisting of several basins and managing by multiple entities. All species moved between basins, but only rarely moved outside tagging areas. The recapture rate of pikeperch was higher than roach and bream. Tagged fish consistently crossed municipality borders and water ownership units, thereby forming shared stocks, which underlined the importance of cooperation in lake restoration and a need to unite fragmented water ownership. Management of fisheries for cyprinid fishes could be more efficient if fishing targeted the most suitable areas without considering restrictions due to fragmented water ownership. Tagging data provided information on which parts of a large lake should be subjected to uniform pikeperch fisheries management. The importance of other species catch varied between different parts of the lake, thereby requiring different fishing regulations. Tagging data on common fish species provided valuable information on fish movements to support spatially explicit fisheries management. [ABSTRACT FROM AUTHOR]

Effective management of migrating fish stocks requires an understanding of population structure and each stock's contribution to the fishery. Water bodies spanning across national borders pose a particular challenge. We investigated the genetic structure of 13 adfluvial brown trout populations from natal rivers and conducted a genetic mixed‐stock analysis of brown trout from the cross‐border Lake Pyaozero Basin in eastern Fennoscandia, using 16 microsatellite loci. Our analysis revealed a clear genetic structure of three distinct geographic groups, consisting of river‐specific populations. The Western and Southern groups, which included 11 rivers, contributed over 90% to the mixed stock in the lacustrine rearing area. This mixed stock of several river‐specific subpopulations renders poorly managed fishing in the area a significant threat to the entire native adfluvial brown trout population complex. [ABSTRACT FROM AUTHOR]

This study aimed to provide data for fisheries management of two threatened guitarfish species, by using linear and geometric morphometric analyses. Linear morphometrics (LM) has limitations in determining minimum catch sizes, whereas geometric morphometrics offers a robust approach to quantifying body form variations with the potential to influence metrics set by legislation. Based on LM analysis, Pseudobatos horkelii were larger than Pseudobatos percellens. Based on geometric morphometric analysis body form differed between the two species, particularly in the head, disk, and posterior region. P. percellens were also sexual dimorphic in body form. Our findings provide valuable insights into permissible catch size limits of these threatened guitarfish and also contribute to improvement of fisheries management strategies where catch is still allowed. The study underscores the necessity of species‐specific and sex‐specific management directives to effectively ensure the population recovery of both guitarfish species. [ABSTRACT FROM AUTHOR]

The social structure of inland fisheries communities tends to place powerful elites in important positions, while local fishermen are subordinate actors. Patronage is a form of social relationship that describes the unequal social structure between these actors. This research aimed to analyze social structure in the inland waters of South Sumatra in the practice of the Lebak Lebung and River Auction (L3S) in OKI District. To achieve this goal, a constructivist paradigm with qualitative research methods was employed, and the sample comprised 39 informants selected as subjects. The data analysis was conducted in three distinct stages, namely data reduction, presentation, and drawing conclusions. The results showed that the regulation of open access for all parties in the local government regime after 1982 created an institutionalized social relations structure where the government, investors, traders, middlemen, and non-fishing actors dominated compared to the fishermen. The participants in this social landscape strived to accumulate capital to enhance their competitiveness within the L3S domain. A patronage system was implemented with middlemen assuming the role of patron and the fishermen acting as their clients. The current institutional social structure has created an unfair distribution of resource benefits for fishing workers. The novelty theories were found in the working relations of the inland waters community of South Sumatra, namely stratified distribution of rights, dual status, multi-stage patronage, and the positive function of patronage for chief fisherman. Further research should be conducted to research policy revitalization and develop strategic inland water management models. [ABSTRACT FROM AUTHOR]

Since anglers and other non-consumptive visitors make a significant contribution to local economies, their satisfaction plays an important role in sustainable management of fisheries in rural areas. We administered a survey to understand whether, and to what extent, site-specific and demographic factors contribute to visitor satisfaction in a lake experiencing a water crisis. Survey data showed that compared to anglers, non-anglers were generally more satisfied with their overall trip experience. Moreover, results from an ordinal logit regression model suggested that anglers who feel a connection with the lake are likely to be more satisfied with their experience. Likewise, fishing quality played an important role in angling satisfaction. Managers may see visitors satisfied by focusing on maintaining a unique quality fishery, enhancing facilities, reducing the presence of litter, and addressing other environmental problems around the lake. [ABSTRACT FROM AUTHOR]

Simple Summary: In this study, the feeding habits, trophic niches, and spatial niches of Pennahia pawak and Pennahia anea were investigated with the aim of exploring the coexistence and competition mechanism of these two species in the Beibu Gulf. The results indicate that both P. pawak and P. anea exhibit feeding shifts and differentiation in their trophic and spatial niches. The study of trophic relationships among closely related species plays an important role in deepening our understanding of the resource utilization characteristics, differentiation patterns, and population dynamics of co-occurring species in the same habitat. This research uses two congeneric fish species, Pennahia pawak and Pennahia anea, as examples. Based on a stomach content analysis and a carbon–nitrogen stable isotope analysis, a comparative analysis of their feeding habits and trophic niches is conducted. Additionally, a spatial niche analysis is employed to explore the coexistence and competitive mechanisms between these two closely related fish species. The results show that specialized feeding habits mitigate intraspecific competition as the population densities increase. The carbon and nitrogen stable isotope analysis reveals variations in the feeding habits and trophic levels with body length, indicating adaptive shifts in prey selection. Despite similar food resources, niche differentiation arises due to differences in dominant prey, facilitating coexistence. Differences in spatial niche further contribute to niche separation and coexistence. In resource-limited environments, species such as Pennahia utilize trophic and spatial niche differentiation to collectively exploit resources and achieve coexistence, with implications for fishery management favoring Pennahia resource occupancy capabilities. [ABSTRACT FROM AUTHOR]

Marine fishery carbon emissions play a significant role in agricultural carbon emissions, making resource allocation a crucial topic for the overall marine ecological protection. This paper evaluates the dynamic iteration method as a research approach with the factors of resource allocation consisting of value assessment, optimization objective, difference between value assessment and objective, and optimization calculation. The paper selects the shadow price from the Super-SBM model as the judgment function for the goal value, aiming for the fairness criterion. From an equity standpoint, the allocation of carbon resources in marine capture fisheries proves to be unreasonable. The fishery model exhibits an excessive supply of carbon resources, resulting in wastage, while the green fishery model faces a relatively limited supply, with a focus on energy conservation and environmental protection. To address this issue, this paper proposes a new method and discusses the corrective results. This result shows that the stabilization point achieved is a short-term equilibrium rather than a long-term one. By rectifying the social contradiction of profit-oriented approaches, this research provides a fresh perspective for economic studies and applications, particularly in industrial layout and resource utilization optimization. [ABSTRACT FROM AUTHOR]

In 1992, the UN banned the use of large‐scale pelagic driftnets on the high seas (UNGA Resolution 46/215). Three decades later, however, drift gillnets remain one of the primary fishing gears in the Indian Ocean, accounting for approximately 30% of tuna catches in this ocean. Recent estimates indicate that several million small cetaceans have been killed in Indian Ocean gillnets over the past few decades. National agencies and the regional fisheries management organization charged with managing tuna fisheries, the Indian Ocean Tuna Commission, have yet to effectively document the bycatch of small cetaceans in these fisheries. Here, we review current information on cetacean bycatch in Indian Ocean drift gillnets and propose potential solutions to this important conservation issue. [ABSTRACT FROM AUTHOR]

The tuna fishery resources, particularly yellowfin tuna (YFT), in Ternate waters, North Maluku, Indonesia (fishery management area 715), are currently classified as fully exploited at 0.97% utilization rate of the available potentials, i.e., 31.659 ton/year. This calls for an attempt to manage the yellowfin tuna in such a way that its existence in the waters can be maintained. Studies on fish population parameters are an effort to obtain scientific information as a recommendation for sustainable fisheries management. This research used experimental fishing by measuring the fish's length. Then, its population was estimated using FISAT II program, and its spawning potential ratio (SPR) was analyzed using length based-spawning potential ratio (LB-SPR) software. It was expected that this would be able to give the yellowfin tuna current status and condition in Ternate waters. Conducted from May through August 2023, and analyzing 4,904 fish, the research managed to determine the population parameters of yellowfin tuna in Ternate waters. Its asymptotic length (L8), growth coefficient (K) and t0 were 117.60 cm, 1.4 per year, and 0.17 year, respectively. These were then plotted to obtain a von Bertalanffy growth curve using the formula Lt = 117,60*(1-Exp-1,4(t-0,17). From the analysis, it was found that the fish total mortality, natural mortality and captive mortality rates were 3.89, 1.55, and 2.34, respectively. Furthermore, it was found that recruitment occurred twice a year, i.e., on March and August at 6.72 and 25.18%, with the Y/R value being 0.039 and B/R value of 0.482. Meanwhile, the spawning potential ratio (SPR) value was 19%, indicating that the utilization rate had been over exploited (SPR< 20%) and it was supported by the fact that the exploitation rate value had been over 0.60 (over fishing) from the Emax value (0.421). Therefore, management is needed to ensure the sustainability of yellowfin tuna stocks. [ABSTRACT FROM AUTHOR]

This study investigated Aristaeomorpha foliacea, the exclusive species of Aristaeomorpha in the Mediterranean, Egypt, employing morphometric, molecular, and phylogenetic analyses. Morphometric assessments unveiled notable size variations between males and females, with males exhibiting a negative allometric growth pattern during spring. Utilizing COI and 16S rRNA genes, molecular analysis demonstrated congruence between morphometrically and molecular taxonomy. Phylogenetic insights revealed genetic relationships between A. foliacea populations from Egypt, Portugal, Italy, Malta, and China, suggesting a migratory pattern from the Atlantic to the Mediterranean. The study identified a moderate genetic diversity in A. foliacea, with six haplotypes in both COI and 16S rRNA regions, providing evolutionary insights. The integration of morphometric identification and phylogenetic study proved instrumental in elucidating the evolutionary relationships of this shrimp species. This interdisciplinary approach contributes valuable morphometric information for fisheries management, emphasizing the need for combined morphometric and DNA-based assessments for effective species identification and conservation. The research enhanced our understanding of A. foliacea in the Mediterranean, emphasizing the necessity for comprehensive approaches to species characterization and conservation. [ABSTRACT FROM AUTHOR]

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

As the largest lake in South China, Wanlv Lake is also an important drinking water source for Guangdong and Hong Kong and is responsible for water supplying of more than 40 million people in the Guangdong-Hong Kong-Macao Greater Bay Area. The study of fish diversity in Wanlv Lake can help us to effectively understand the changes and states of its aquatic ecosystem and provide scientific basis for natural ecological protection, biodiversity, sustainable use and scientific management of fishery resources. However, research on the lake's fish is scarce. The high throughput environmental DNA metabarcoding technology (eDNA technology) of the mitochondrial 12S rRNA gene sequence was herein used to conduct a preliminary exploration of Wanlv Lake fish diversity. A total of 10 sampling sites were set up to monitor fish diversity and analyze the composition and richness of the species. The results revealed a total of 83 genera in 42 families and 17 orders of fish in the lake, with the highest proportion found in Cypriniformes (38 species), accounting for 45.24% of the total. Five alien species and eight rare and endangered species were also detected. The proportion of invasive species was 5.95%, and the combined proportion of rare and endangered species was 9.52%. The results indicated that Wanlv Lake serves as an important drinking water source, and overall, the condition of fish is satisfactory. However, proactive measures should be implemented to control the overpopulation of invasive species, as their unchecked proliferation may lead to a decline in species abundance, particularly among endangered species. This was the first overall assessment report on fish of the Wanlv Lake via 12S rRNA; the results herein lay a foundation for water quality assessment of Wanlv Lake as a drinking water source. [ABSTRACT FROM AUTHOR]

The deep-sea Caribbean lobster (Metanephrops binghami) and the Norway lobster (Nephrops norvegicus) are Nephropidae species of high commercial interest. Although the first one still remains unexploited, the second is overexploited in the Mediterranean Sea. For effective fisheries management, size at sexual maturity is an essential indicator to protect immature individuals from exploitation. The estimation of this indicator can, however, be biased due to the difficulty of differentiating juveniles from adults by their size structure due to the natural process of molting. This study aims to estimate the size at sexual maturity of M. binghami and N. norvegicus females by comparing the effectiveness of the morphometric method versus the macroscopic evaluation of gonad maturity. Samples of M. binghami were collected from the Colombian Caribbean Sea in August and December 2009, March and May 2010, and August 2020 to May 2021. Samples of N. norvegicus were collected from the northwestern Mediterranean Sea from 2019 to 2022. Similar sizes at sexual maturity were found for M. binghami between the morphometric approach (ranging from 28.6 to 33.9 mm cephalothorax length, CL) and the gonadal staging approach (31.4 mm CL). Conversely, for N. norvegicus, the morphometric approach yielded higher measurements (between 27.2 and 30.4 mm CL) than the gonadal approach (26.0 mm CL). This discrepancy might stem from the intense fishing overexploitation conditions of N. norvergicus, leading to a physiological adaptation that enables earlier gonadal maturation at faster rates than morphometric adaptation. Further research is required to elucidate these discrepancies and the effect of overexploitation on physiological (i.e., mature gonads) and functional maturity (i.e., capacity to brood eggs at a larger size). [ABSTRACT FROM AUTHOR]

Modern fisheries management strives to balance opposing goals of protection for weak stocks and opportunity for harvesting healthy stocks. Test fisheries can aid management of anadromous fishes if they can forecast the strength and timing of an annual run with adequate time to allow fisheries planning. Integration of genetic stock identification (GSI) can further maximize utility of test fisheries by resolving run forecasts into weak‐ and healthy‐stock subcomponents. Using 5 years (2017–2022) of test fishery data, our study evaluated accuracy, resolution, and lead time of predictions for stock‐specific run timing and abundance of Columbia River spring Chinook salmon (Oncorhynchus tshawytscha). We determined if this test fishery (1) could use visual stock identification (VSI) to forecast at the coarse stock resolution (i.e., classification of "lower" vs. "upriver" stocks) upon which current management is based and (2) could be enhanced with GSI to forecast at higher stock resolution. VSI accurately identified coarse stocks (83.3% GSI concordance), and estimated a proxy for abundance (catch per unit effort, CPUE) of the upriver stock in the test fishery that was correlated (R2 = 0.90) with spring Chinook salmon abundance at Bonneville dam (Rkm 235). Salmon travel rates (~8.6 Rkm/day) provided predictions with 2‐week lead time prior to dam passage. Importantly, GSI resolved this predictive ability as finely as the hatchery broodstock level. Lower river stock CPUE in the test fishery was correlated with abundance at Willamette Falls (Rkm 196, R2 = 0.62), but could not be as finely resolved as achieved for upriver stocks. We described steps to combine VSI and GSI to provide timely in‐season information and with prediction accuracy of ~12.4 mean absolute percentage error and high stock resolution to help plan Columbia River mainstem fisheries. [ABSTRACT FROM AUTHOR]

Thaisella chocolata is a marine gastropod (family Muricidae) occurring from northern Peru to central Chile. It is of economic importance in these countries, where hundreds of tons are caught every year. In combination with El Niño–Southern Oscillation events, fishing activity has led to the collapse of Chilean populations, raising concerns about the state of Peruvian populations. The aim of this study is to assess the demography, genetic diversity and connectivity of T. chocolata along the Peruvian coast. This would provide important insights into the resilience of this species to anthropogenic disturbance. In this study, four locations along the coast of Peru were investigated for the first time. Mitochondrial cytochrome c oxidase subunit I (COI) sequences were obtained from 116 individuals and four microsatellites from 95 individuals. Both COI (combined with 156 publicly available sequences) and microsatellite data revealed very low genetic differentiation, despite a few significant φ ST and F ST values between population pairs. The most likely gene flow model (MIGRATE-N) is panmixia between all locations, with gene flow occurring equally northwards and southwards. This pattern may be related to the surface currents along the Peruvian coastline combined with the high pelagic larval duration of T. chocolata. Hyperdiversity was found for the COI marker (π syn > 5%). Microsatellite loci were also polymorphic, with a mean diversity of 12.69 alleles per locus per population. No recent population bottleneck was observed (microsatellite data), while at least one past demographic expansion was suggested (COI data). Given the high genetic diversity and connectivity, T. chocolata is expected to show high evolutionary resilience and can be considered as one management unit in terms of fisheries management. However, further studies, on, for example, the characterization of effective population size (using numerous nuclear loci), are required to confirm this hypothesis. In addition, precautionary fisheries measures should be maintained, given the recent collapse of T. chocolata stocks in Chile. [ABSTRACT FROM AUTHOR]

Population monitoring of Atlantic salmon (Salmo salar L.) abundance is an essential element to understand annual stock variability and inform fisheries management processes. Smolts are the life stage marking the transition from the freshwater to the marine phase of anadromous Atlantic salmon. Estimating smolt abundance allows for subsequent inferences on freshwater and marine survival rates. Annual abundances of out‐migrating Atlantic salmon smolts were estimated using Bayesian models and an 18‐year capture–mark–recapture time series from two to five trapping locations within the Restigouche River (Canada) catchment. Some of the trapping locations were at the outlet of large upstream tributaries, and these sampled a portion of the total out‐migrating population of smolts for the watershed, whereas others were located just above the head of tide of the Restigouche River and sampled the entire run of salmon smolts. Due to logistic and environmental conditions, not all trapping locations were operational each year. Additionally, recapture rates were relatively low (<5%), and the absolute number of recaptures was relatively few (most often a few dozen), leading to incoherent and highly uncertain estimates of tributary‐specific and whole catchment abundance estimates when the data were modeled independently among trapping locations and years. Several models of increasing complexity were tested using simulated data, and the best‐performing model in terms of bias and precision incorporated a hierarchical structure among years on the catchability parameters and included an explicit spatial structure to account for the annual variations in the number of sampled locations within the watershed. When the best model was applied to the Restigouche River catchment dataset, the annual smolt abundance estimates varied from 250,000 to 1 million smolts, and the subbasin estimates of abundance were consistent with the spatial structure of the monitoring programme. Ultimately, increasing the probabilities of capture and the absolute number of recaptures at the different traps will be required to improve the precision and reduce the bias of the estimates of smolt abundance for the entire basin and within subbasins of the watershed. The model and approach provide a significant improvement in the models used to date based on independent estimates of abundance by trapping location and year. Total abundance and relative production in discrete spawning, nesting, or rearing areas provide critical information to appropriately understand and manage the threats to species that can occur at subpopulation spatial scales. [ABSTRACT FROM AUTHOR]

Understanding age and growth are important for fisheries science and management; however, age data are not routinely collected for many populations. We propose and test a method of borrowing age–length data across increasingly broader spatiotemporal levels to create a hierarchical age–length key (HALK). We assessed this method by comparing growth and mortality metrics to those estimated from lake–year age–length keys ages using seven common freshwater fish species across the upper Midwestern United States. Levels used for data borrowing began most specifically by borrowing within lake across time and increased in breadth to include data within the Hydrologic Unit Code (HUC) 10 watershed, HUC8 watershed, Level III Ecoregion, and finally a species‐wide data ALK using all available data with our study for a species. Median deviation in mean length of age‐3 fish was within 1 cm for the most specific HALK levels, and median deviation in total annual mortality was close to 0 for most species when borrowing occurred within HUC10 and HUC8 watersheds. Percent error in growth curves increased with data borrowing, but plateaued—or even decreased—for some species when data borrowing expanded across spatial levels. We present the HALK as a method for gaining age information about a fishery when age data are unavailable. [ABSTRACT FROM AUTHOR]

Seascape genomics gives insight into the geographic and environmental factors shaping local adaptations. It improves the understanding of the potential effects of climate change, which is relevant to provide the basis for the international management of fishery resources. The pink abalone (Haliotis corrugata) is distributed from California, United States to Baja California Sur, Mexico, exposed to a latitudinal environmental gradient in the California Current System. Management of the pink abalone contrasts between Mexico and the United States; Mexico has an active fishery organized in four administrative areas, while the United States has kept the fishery in permanent closure since 1996. However, the impact of environmental factors on genetic variation along the species distribution remains unknown, and understanding this relationship is crucial for effective spatial management strategies. This study aims to investigate the neutral and adaptive genomic structure of H. corrugata. A total of 203 samples from 13 locations were processed using ddRADseq, and covering the species' distribution. Overall, 2,231 neutral, nine potentially adaptive and three genomic–environmental association loci were detected. The neutral structure identified two groups: 1) California, United States and 2) Baja California Peninsula, México. In addition, the adaptive structure analysis also detected two groups with genetic divergence observed at Punta Eugenia. Notably, the seawater temperature significantly correlated with the northern group (temperate) and the southern (warmer) group. This study is a valuable foundation for future research and conservation initiatives, emphasizing the importance of considering neutral and adaptive genetic factors when developing management strategies for marine species. [ABSTRACT FROM AUTHOR]

Simple Summary: Pampus is a genus of fish of commercial importance in Asia. This is a comprehensive study on the species delimitation and evolution history of Pampus species. This study integrated information on the skeletal structure and mitochondrial and nuclear molecular data of the genus Pampus to define their species delimitation. Based on these findings, we suggest that P. argenteus and P. echinogaster should be classified as the same species and P. liuorum is speculated to be a valid species. P. cinereus is closely related to P. minor, P. chinensis and P. punctatissimus, but these are different species. Pampus can be divided into six species: P. argenteus, P. punctatissimus, P. cinereus, P. chinensis, P. minor, and P. liuorum. The aim of this study was to resolve the controversies about the phylogeny and taxonomy of Pampus and provide a robust delimitation of Pampus for fisheries management. Pampus is a widespread species of fish in the western Pacific and Indian Oceans that has significant commercial worth. Its evolutionary history and phylogenetics are still poorly understood, and details on its intraspecific taxonomy are debatable, despite some morphological and molecular research. Here, we analyzed this species using skeletal structure data as well as nuclear (S7 gene) and mitochondrial genetic information (COI, D-loop and mitogenomes). We found that the genetic distance between P. argenteus and P. echinogaster was much smaller than that between other Pampus species, and both maximum likelihood and Bayesian phylogenetic trees yielded almost identical tree topologies. An additional and adjacent M repeat was found in the downstream region of the IQM gene cluster of P. argenteus and P. echinogaster, and the trnL2 gene of P. minor was translocated. The genus Pampus experienced early rapid radiation during the Palaeocene with major lineages diversifying within a relatively narrow timescale. Additionally, three different methods were conducted to distinguish the genus Pampus species, proving that P. argenteus and P. echinogaster are the same species, and P. liuorum is speculated to be a valid species. Overall, our study provides new insights not only into the evolutionary history of Pampus but its intraspecific taxonomy as well. [ABSTRACT FROM AUTHOR]

This decade represents a critical period to profoundly rethink human–nature interactions in order to address the interwoven climate and biodiversity crises. Marine Protected Areas (MPAs) demonstrate promise for increasing ecosystem resilience and reversing habitat and population declines, but outcomes vary considerably from context to context. Partially protected areas offer a compromise between ecological recovery and the social needs of local communities, but their success is contingent on an array of factors. This in-depth review summarizes 15 years of marine conservation research and impact in Lyme Bay (southwest UK), to serve as a model for the future adoption of partially protected MPAs. The findings from the UK's longest integrated socioecological monitoring MPA study are presented and supplemented by an evaluation of the whole-site management approach as a core element of Lyme Bay's achievements. The journey from research to improved monitoring and ambitious policy is illustrated within and interspersed with stories of novel discoveries, ongoing challenges, and method developments. What started as a dedicated group of community members has grown into an immense collaboration between fishers, scientists, NGOs, and regulators, and their combined efforts have sent ripple effects of positive change across the globe. [ABSTRACT FROM AUTHOR]