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Observers are deployed on commercial fishing trips to collect representative samples of discard rates. However, fishers may change their fishing habits when an observer is onboard ("observer effect") or observer programs may over- or under-sample portions of the fleet ("deployment effect"). If the extent of these effects are substantial, observer data will not be representative of unobserved trips, potentially biasing the estimation of discards. This sampling bias can impact catch monitoring, stock assessments, and fishery management. The purpose of this study was to examine the power and error rate of several published methods for detecting an observer effect using a simulation of observer and deployment effects at varying sampling ratios (i.e., observer coverage) for several sample statistics. The simplest methods (t-test and F-test for difference of means and variances) provided an accurate although imprecise estimate of the observer effect size, but only when there were no deployment effects. A generalized linear mixed effects model (GLMM) was also not reliable for detecting small bias, but was not confounded by deployment effects and was relatively robust to changing coverage rates. The most complicated tests involved comparing differences in trip characteristics between subsequent trips for observed-unobserved and unobserved-unobserved pairs. These tests were able to detect smaller observer effects and were not confounded by deployment effects, but were unreliable at high coverage rates (>60%), producing both high false positive and false negative rates. Sensitivity tests also showed differing detection accuracy as the distribution of the metric of interest changed. Thus, the optimal test for detecting an observer effect will depend on the metric of interest, the coverage rate, and whether a deployment effect exists. An example from the New England groundfish fishery is provided to illustrate how conflicting results may be explained. Results should always be considered carefully when declaring that an observer effect is or is not occurring because of the sensitivity of the tests. • Simulations show that detecting fisheries observer effects are not straightforward. • Tests can be sensitive to data distributions and observer coverage rates. • More complex tests are needed when deployment effects may also be present. • Accurate detection of observer and deployment effects may affect policy decisions. [ABSTRACT FROM AUTHOR]

The aim of stock assessment is to provide managers with an understanding of the biomass and age-/size-composition of a stock, stock status (ideally relative to target and reference points), and to support management decision making, often through projections and application of harvest control rules. Stock assessments are increasingly being used to form the basis for the operating models used to evaluate the ability of management strategies to achieve the goals of fisheries management. Stock assessments for rock lobsters were among the first to adopt size-structured population models as the basis for stock assessment, and population model-based stock assessments have been used extensively to evaluate management strategies for rock lobster stocks in the USA, Australia, New Zealand and South Africa. This paper identifies how closely population model-based stock assessments for rock lobsters satisfy the guidelines identified for best practices for conducting stock assessments during meetings of, for example, the Center for the Advancement of Population Assessment Methodology and papers identifying best practice guidelines for stock assessment. The paper highlights some key directions for stock assessment science for rock lobsters, including considerations related to environmental variation and climate change. [ABSTRACT FROM AUTHOR]

The quantification of fishing information on fishing vessels is a prerequisite for implementing refined management of quota-based fishing. In order to address the target detection and information quantification issues in the quota-based fishing of Acetes chinensis , this study installed an Electronic Monitoring (EM) system on Acetes chinensis fishing vessels. Using the EM system video as a data source. Based on YOLOv7, an improved object detection algorithm (YOLOv7-DCN) is proposed. Additionally, drawing on the main ideas of the SORT algorithm, a target counting algorithm is also proposed (YOLOv7-DCN-SORT). YOLOv7-DCN object detection algorithm uses DCNv2 as the backbone network to detect the main targets in fishing vessel operations, improving the network's ability to detect deformable targets. The YOLOv7-DCN-SORT target counting algorithm utilizes the YOLOv7-DCN obtained in the detection phase as the target detection model. It applies the Kalman filter and Hungarian algorithm from the SORT algorithm to track and predict the counted targets. By setting collision detection lines, timestamps, thresholds, and counters, this algorithm can accurately count the number of baskets filled with Acetes chinensis and the number of nets deployed during fishing operations. The results show that: 1) The improved YOLOv7-DCN achieved precision, recall, mAP, and F1-score of 98.21%, 98.43%, 99.19%, and 98.33%, respectively, for each target detection category on the test set. These values represent improvements of 2.06%, 0.64%, 0.08%, and 1.37% compared to the original YOLOv7 model. 2) The YOLOv7-DCN-SORT algorithm achieved counting accuracy rates of 82.00% for counting the number of Acetes chinensis baskets and 96.61% for the number of deployed nets. In summary, this study provides methods for automated recording and intelligent information processing in operations on offshore fishing vessels, serving as a reference for quota-based fishing management decisions. [Display omitted] • A model was developed to detect the targets operations on Acetes fishing vessels. • A model was developed for counting and sorting on Acetes fishing vessels. • Improving Target Detection Models with Deformable Convolution • The proposed model outperformed other state-of-the-art algorithms. [ABSTRACT FROM AUTHOR]

Mixed fisheries capture multiple species simultaneously, posing significant challenges to fisheries assessment and management, and leading to systematic risk of overfishing. While the Multi-Species Total Allowable Catch (MSTAC) approach provides a feasible tool for managing mixed fisheries, there remains a lack of clarity on how to design effective management units within MSTAC. To achieve robust and conservative management, we designed and evaluated different schemes of MSTAC based on the species portfolio effect that is crucial for multispecies productivity. We considered four ecological traits to construct the MSTAC schemes, including habitat preference, feeding mode, body size and thermophily. We simulated the population dynamics of mixed fisheries and the biotic and technical interactions within the fish community using a dynamic multispecies size-spectrum model (MSSM) developed for the North Yellow Sea, China. We assessed the effects of these schemes in terms of fishery yield, stock biomass, potential productivity, and risk of depletion. Our evaluation suggests that appropriate portfolio-based schemes could enhance sustainability better than maintaining current yield through Single-Species TAC (SSTAC), which might result in rapid productivity losses and a higher risk of depletion. All the candidate schemes exhibit necessary trade-off between fisheries yields and depletion risks of the fish community. Notably, the size-based scheme provides significant benefits in buffering against depletion risks while conserving the potential productivity of the holistic fish community, followed by the habitat-based scheme. We highlight that the emergent portfolio effects from the aggregated MSTAC can enhance sustainability in mixed fisheries management and potentially serve as "insurance" against climate variability. [ABSTRACT FROM AUTHOR]

The peppery furrow shell Scrobicularia plana is a commercial valuable bivalve in the east Atlantic and Mediterranean Sea. To ensure the sustainability of this resource and implement efficient management strategies, it is essential to understand the life history traits of the species, such as growth, reproduction, and size at first maturity. These features were investigated in the southern range of the species' European distribution, specifically in Ria de Aveiro (Portugal), and compared to other geographical areas. At Ria de Aveiro S. plana spawns from June to October, with a peak in August/September, aligning with the typical reproductive pattern of mid latitude European populations. The condition index is lowest in March and highest in May just before spawning. Sexual maturity (L 50 = 27 mm SL) is attained at approximately 1 year of age, enabling offspring to reproduce in the subsequent spawning season. In this study, the overall sex ratio did not differ significantly from 1:1. Hermaphroditism (ovotestis) was detected in one specimen, representing 0.3% of the total examined males. Shell rings are formed annually during growth cessation in fall/winter and become conspicuous when growth resumes in March. The growth equation parameters, estimated from surface shell ring analysis and internal shell microgrowth bands, were: Lt = 58.1[1 - e−0.46(t −0.09)]; Lt = 54.7[1 - e−0.53(t −0.30)], respectively. Values for K and L ∞ are among the highest recorded for the species, highlighting the growth performance of S. plana in the Ria de Aveiro and its potential for commercial exploitation. An analysis of morphometric relationships between shell length, height, and width was performed to optimize the harvesting process of S. plana. Management measures are proposed for the fishery of S. plana in Ria de Aveiro, based on the species' biological traits. [Display omitted] • Reproductive biology of Scrobicularia plana is described. • Condition index exhibited a seasonal pattern linked to the reproductive cycle. • Fast growth and rapid maturity allow first-year reproduction. • A minimum conservation reference size of 27 mm SL can enhance sustainable exploitation. • A closed fishing season between August and November should be enforced. [ABSTRACT FROM AUTHOR]

Estimating the survivorship of discarded fish is often crucial for stock assessment and resultant management of fisheries resources. In order to assess the survivorship of cuckoo ray (Leucoraja naevus) caught in commercial bottom trawl fisheries, experiments involving French and Irish fisheries were conducted. These experiments were particularly challenging considering the fisheries are offshore. Data from these experiments were analysed jointly in this study. Results from monitoring of individuals held in captivity in onshore facilities and observations of vitality status were combined to produce estimates of long-term survival rates across fishing trips in all four seasons. These rates varied greatly between fishing trips and ranged between 3.6% and 26%. Based on indications that the observed mortality may be at least partly attributable to the conditions of captivity, we propose an approach to reduce the underestimation bias when estimating discard survival. This approach produced higher bounds for the estimated discard survival rates. The estimated survival rates are lower than those of other skate species in the North-East Atlantic, suggesting the cuckoo ray is less resilient to trawl-and-release, although previous studies were conducted in shallower water and with shorter haul duration. • The study combined vitality assessment in all seasons and monitoring in captivity. • Estimated survivorship is poor compared to other skates in different fisheries. • Survival rates varied markedly between fishing trips. • A suggestion was presented to correct for mortality of controls in survival rates. [ABSTRACT FROM AUTHOR]

This study examines long-run changes in productivity within the Australian Northern prawn fishery, an input control managed fishery. Productivity change is estimated through a Malmquist Index over a 20-year period from 1999–2000 to 2019–2020, decomposing productivity into technical change and efficiency change components. Fluctuations in the Malmquist Index over the period of the study were driven primarily by the technical change component, reflecting changes in stock abundance, technical improvements, and the effects of management. The efficiency change index was found to be relatively stable throughout the study period. The findings suggests that changes in performance of the fleet are driven largely by exogenous factors impacting catches, with limited change in the relative skill of fishers. • Sources of productivity change in Australia's Northern Prawn Fishery were assessed. • Productivity change was decomposed into technical change and efficiency change. • Malmquist index was driven by the fluctuating technical change component. • Efficiency change index remained relatively stable over time. • Method is a practical fisheries management tool. [ABSTRACT FROM AUTHOR]

Habitat preferences influence partitioning in many marine taxa that can inform fisheries management. Despite this, little is known about how habitat partitioning contributes to spatial distributions in many commercially important species. This study aims to investigate habitat partitioning and influential variables affecting the distribution in Moreton Bay bug species Thenus parindicus and Thenus australiensis for the benefit of management on the east coast of Queensland, Australia. These Scyllarid lobsters spend much of their lives buried within sediment, but little research focuses on what influences the distribution of each species. In this study, a fishery-independent survey was conducted in a key commercial trawling area off the coast of Townsville to determine Thenus species distributions and habitat preferences. Variables used to examine the habitat preferences and distributions of both species included depth, sediment grain size, Trask sorting coefficient and calcium carbonate content. We found that all variables evaluated significantly affected species distributions. Multivariate analyses suggest that Trask sediment sorting coefficient and depth were the strongest influential variables. This contrasts with previous findings that mean grain size is the most important sediment parameter influencing Thenus distributions. The results indicate habitat partitioning between T. parindicus and T. australiensis but not habitat exclusion. These findings, along with the likely influential variables of species' distributions will help better understand the habitat ecology of these lobsters and inform management for the Moreton Bay bug fishery. [ABSTRACT FROM AUTHOR]

Scomber colias Gmelin, 1789 is of growing interest as a commercial species, making it one of the most demanding fish on the northwest coasts of Africa (NWA). However, relevant data on the stock structure and connectivity of S. colias along the NWA is scarce. The Eastern Central Atlantic Fisheries Committee (CECAF) assumes the existence of two stocks (a northern and a southern stock) between Morocco and Senegal, separated by Cap Boujdour. However, given the absence of relevant biological information on the migration and connectivity of the species, CECAF suggests a joint assessment of the two stocks. Otoliths can be used as natural tracers to study the population structure, fish movements, and habitat connectivity of fish. Otolith morphology, for instance, is a phenotypic trait with a genetic background that usually responds to environmental variables. This study used otolith shape analysis (wavelets) to investigate S. colias stock structure along the NWA, from Morocco to Senegal. Fish were collected between September and December of 2019 by a scientific survey in ten sites (Larache, Casablanca, Safi, Agadir, Tantan, Tarfaya, South of Boujdour, North of Cape Barbas, south Mauritania and Senegal) using a purse seine. The hereby results showed a highly significant regional differentiation among the sites, suggesting the existence of two population-units, with an overall correct re-classification of 91% to the two clusters. This dataset indicates the existence of an oceanographic barrier at the level of 28°N (Tarfaya), which limits the connectivity between the two stocks. Moreover, the mean otolith shape based on wavelet reconstruction for the two population-units revealed high phenotypic plasticity for S. colias otoliths. The broad variance between the two morphotypes highlights the environmental heterogeneity of the Atlantic Northwest African waters. The variation in the rostrum and anti-rostrum of S. colias otoliths is most likely due to genetic diversity or long-term isolation of the two population-units. The hereby data support the hypothesis that S. colias in the NWA is divided into two stocks with limited connectivity. In terms of fisheries management, this study recommends a fine-scale stock assessment. • 300 Scomber colias were studied using otolith shape analysis along the Northwest coast of Africa. • Otolith shape showed significant phenotypic differentiation between sites. • Two phenotypic populations could be discerned. • A phylogeography barrier located around the 28th parallel North was found. [ABSTRACT FROM AUTHOR]

Detecting systematic trends in population parameters along large latitudinal patterns and analyzing them under a macroecological framework can provide useful information for fishery management. This becomes crucial for data-poor fisheries. Combining a metabolic-based argument to explain the decrease in size towards warmer environments (i.e. the temperature size rule, TSR) with the Beverton and Holt life-history invariants (BH) we derived a series of predictions about population parameters and tested them with empirical data from the endemic shrimp Artemesia longinaris (Bate, 1888) along its entire distribution area in the Southwestern Atlantic Ocean (SWAO), from Brazil (21°S) to Argentina (43°S). We also provide novel information on the population structure of A. longinaris captured in Uruguayan waters (34°) filling a relevant gap in a transitional region in the SWAO. We found no relationship between latitude and the maximum carapace length (CL max), however, both CL max and the size at first maturity (CL 50) showed a negative relationship with maximum temperature consistent with TSR. Changes in CL max and CL 50 presented equal temperature dependence (0.23 ± 0.165, and 0.25 ± 0.236, respectively). The BH invariance of the ratio of size at maturity to maximum size of A. longinaris populations captured in the SWAO (average=0.57; sd=0.09) showed no latitudinal trend as expected and was within the expected theoretical value (∼0.66). Our results corroborate that at higher latitudes individuals reach sexual maturity at larger sizes than those living in lower latitudes. We also discuss the use of the macroecological approach to provide clues on key demographic attributes that are especially relevant in data-poor fisheries. • Macroecological predictions provide vital insights for data-poor fisheries management. • Combining BH and Von Bertallanfy predicts key demographic attributes. • Temperature size rule was a main determinant of large-scale population size trends. • Penaidea shrimp populations structure along biogeographical regions. [ABSTRACT FROM AUTHOR]

Area-based fisheries management measures (ABFMs) have evolved beyond fisheries regulation to encompass broader conservation goals. This mini-review provides key recommendations to guide the science-based implementation of effective ABFMs for rebuilding fisheries and conserving marine biodiversity within the Kunming-Montreal Global Biodiversity Framework. Drawing from a comprehensive review of global literature, we catalogued 232 recommended actions. Most recommendations focused on enhancing informed and more effective area-based management (n = 115) and optimizing ABFMs planning (n = 70). Fewer were related to transparent and inclusive area-based management (n = 25) and adaptability to change (n = 22). For effective area-based fisheries management, the following actions are recommended: (1) advancing informed and effective management through enhanced data collection, responsive measures, regular monitoring, interdisciplinary research and efficient control and surveillance; (2) refining ABFMs planning to account for the complexity of marine ecosystems integrating ABFMs with other measures, considering socio-economic aspects, designing connective, representative and comprehensive ABFMs and considering ABFMs applicability and transferability; (3) nurturing transparent and inclusive management through intergovernmental cooperation, transparent and equitable governance and increased stakeholder engagement; and (4) embracing adaptability through responsiveness to change, dynamic ABFMs, and addressing climate-related shifts. These recommendations offer a comprehensive roadmap for strengthening ABFMs in a changing global ecosystem in support of the Kunming-Montreal Global Biodiversity Framework. [Display omitted] • This review provides key recommendations for area-based fisheries management. • 232 actions were recorded for effective area-based fisheries management. • Most of them were related to informed and more effective management. • Actions for improved planning & transparent/inclusive management were recommended. • Also actions related to responsiveness to change were suggested. [ABSTRACT FROM AUTHOR]

Sharks and rays are widely perceived to have slow reproductive rates and, thus, are often considered highly susceptible to population declines from commercial fishing. However, the reproductive biology of sharks is highly diverse, and some species can sustainably support significant commercial harvest. Small sharks are commonly caught and discarded as bycatch in several Australian and international fisheries. This represents either a wasted resource that could potentially be sustainably utilised, or a potential conservation issue if overharvesting occurs. This study examines the reproductive biology of two small-bodied sharks in the Northern Territory, Australia. Carcharhinus coatesi (n = 726) and Rhizoprionodon acutus (n = 179) were collected between May 2018 and November 2019 from commercial trawl fisheries. Maximum lengths in both species were higher in females than males (C. coatesi : F = 862 mm, M = 822 mm; R. acutus : F = 862 mm, M = 835 mm). Size at 50% maturation size C. coatesi : F = 655 mm, M = 664 mm; R. acutus : F = 682 mm. Size-at-maturity that the logistic model predicted for male R. acutus (715 mm) appears to represent size at full maturation and this study could not determine 50% maturation size. Litter sizes were small in both species, with C. coatesi producing 1–2 pups (mean 1.9) and R. acutus producing 1–4 pups (mean 2.8). Both species gave birth to large pups when compared to other shark species (C. coatesi : 370 - 450 mm; R. acutus : 315 – 400 mm), with C. coatesi size-at-birth being 47.6% of maximum female total length, while R. acutus size-at-birth was 41.5% of maximum female total length). Both species reproduced throughout the year, complicating estimation of the gestation period. The reproductive biology of C. coatesi and R. acutus showed considerable spatial and temporal variability when compared to studies from other regions and a past study from the Northern Territory in 1991. Although C. coatesi and R. acutus are currently abundant in the Northern Territory, the low fecundity of both species compared to other small-bodied sharks may limit their potential to sustain high levels of commercial harvest. Any expansion of commercial fishing for these species should be based on detailed consideration of their reproductive biology—in particular their low fecundity—to avoid the declines experienced by other formerly abundant elasmobranchs globally. • C. coatesi and R. acutus are not as productive as other small-bodied sharks, assuming productivity is directly related to fecundity. • Evidence sharks are still abundant, maybe explained by large size-at-birth contributing to reduced natural mortality. • Regionally specific informationis needed for fisheries management as there is primary evidence that R.acutus is a complex of similar species [ABSTRACT FROM AUTHOR]

Identification of stock composition is essential for fish stock assessment and management. Previous studies have suggested that a mixed stock composition of Pacific saury Cololabis saira exists in the northwest Pacific Ocean, but the origins of the stock's components are poorly understood. We analyze the otolith microstructure of Pacific saury collected in high-seas fishing grounds from June–November, 2016–2019, and estimate hatch date and reconstruct otolith growth trajectory before hyaline zone formation. Results confirm that Pacific saury recruiting to the high-seas fishing ground are mainly from a winter-spawned cohort, secondarily from an autumn-spawned cohort, but also with a small proportion from a spring-spawned cohort. Ages of medium (knob length 240–280 mm) and large (knob length > 280 mm) individuals are mainly 8–12 and 18–21 months, respectively. Two growth patterns are reported for individuals with different otolith growth axes in their early life stages. Each year, unsupervised random forest clustering analysis of otolith daily increment widths reveals two Pacific saury groups. One group, with younger age and a later hatching period, shows a consistently higher growth rate than the other, suggesting that the two groups have different hatch dates and locations. These findings permit more accurate prediction of Pacific saury recruitment, and improve the understanding of short-term stock fluctuations to enable more sustainable management of fisheries. [ABSTRACT FROM AUTHOR]

Cryptic speciation was recently verified in Etelis carbunculus , an important component of federally managed bottomfish fisheries in the Pacific Territories of the United States. As a result, archived otolith collections used for fishery assessment are now contaminated with newly described E. boweni in areas where these species co-occur. We compared the efficacy of otolith morphometrics and Fourier transform near-infrared (FT-NIR) spectroscopy to discriminate species first using voucher (i.e., known species) otoliths (n = 93) from the SW Pacific, then applied optimal models to archived otoliths (n = 91) collected around Guam. Significant and distinguishable differences in otolith morphometrics as well as FT-NIR spectral absorbance patterns were observed between E. carbunculus and E. boweni voucher samples. Classification models applied using both morphometric measurements (quadratic discriminant analysis) and FT-NIR spectral data (partial least squares discriminant analysis) were able to predict species with a high (93 – 100%) degree of accuracy despite a relatively large spatial area of specimen collection (± 10° latitude and longitude) and regardless of whether otoliths were whole (i.e., unbroken). Further, each method identified members of newly described E. boweni in the archived collection of E. carbunculus otoliths captured around Guam, providing strong evidence that the species' distributions overlap in this region. The purported identification of both E. carbunculus and E. boweni in the archived catch from Guam has important implications for fisheries management; therefore, it is imperative that the corresponding otolith collections are examined to ensure that the otoliths are assigned to the correct species. • Otolith archives of E. carbunculus must be examined to separate cryptic E. boweni. • Species predictions were highly accurate (93 – 100%) using either method. • FT-NIR spectroscopy is a powerful new method to differentiate cryptic species. • Cryptic E. boweni identified by both methods in Guam otolith archive. [ABSTRACT FROM AUTHOR]

Fishery-independent scientific surveys are highly valuable for monitoring lobsters and other fisheries. Yet, there are relatively few long-term monitoring surveys to support the provision of management advice. A number of challenges can prevent the continuity of long-term monitoring series. This paper uses the 35-year continuous annual dive surveys for Australia's Torres Strait tropical rock lobster (TRL) to overview strengths and limitations of a long-term scientific survey, as well as lessons learnt from having overcome a range of challenges. Fishery-independent surveys are more reliable than fishery-dependent data and are more robust to external shocks such as market drivers and fuel prices. The primary purpose of the surveys is to provide a reliable index of stock abundance together with data to inform on size and age structure, plus model parameters and reference points. Here, we also highlight additional survey benefits including: yielding positive gains relative to cost, facilitating an adaptive management approach that serves as an early warning system, reducing and resolving inter-sector conflicts, reduced frequency of stock assessments, providing data from associated habitat monitoring, improved stakeholder buy-in, utility for development of Operating Models for Management Strategy Evaluation, contribution to achieving certification, contributing to biodiversity agreements and consistent cross-jurisdictional monitoring. We analyse lessons learnt from challenges such as changes in resource management, budget cuts, increased health and safety requirements, maintenance of capability and staff capacity, stakeholder buy-in, need to validate survey results, a pandemic and changing climate. Our experiences highlight why long-term scientific surveys are considered the gold standard for fisheries monitoring and we provide insights for building and maintaining key marine monitoring series. [Display omitted] • Fishery-independent surveys are valuable but challenging to maintain long-term. • Challenges include costs, capacity, management changes, COVID19, climate change. • Survey data robust to extreme events and external system shocks. • Benefits include reliability, positive benefit:cost, habitat data, science buy-in. • Long-term scientific surveys considered the gold standard for fisheries monitoring. [ABSTRACT FROM AUTHOR]

Coral reef fisheries are important as they support the economy, livelihoods, and food security of millions of people worldwide. However, reef fisheries are widely overfished, impacting the abundance and size structure of highly biodiverse fish assemblages. Here, we assessed the effects of fishing on the size structure of exploited coral reef fishes using size spectra analysis, a method that informs about fishing mortality and ecosystem productivity. We used data from over 500 landing site interviews with hook and line fishers in Northeastern Brazil. The data included 18 fishing grounds (i.e., fringing reefs), fishing effort (fishers/km2) of a widely used gear (hooks and line), and 3690 measurements of exploited fish body size. We fitted linear regressions to body size estimates in the catch of each fishing ground to estimate the slopes of the size spectra and tested for a possible effect of fishing effort on those slopes. We found that fishing effort associated with hook and line negatively affected the slopes of size spectra (p = 0.04; R2 = 0.22). This likely occurred because hook and line generally selects for the largest individuals in the assemblage, so that, as expected, higher levels of fishing effort were associated with smaller size of the exploited fishes. Given body size is usually proportional to trophic level in reef fishes, our finding suggests fishing may be disproportionately affecting predators in the study area. Our study provides the first documentation of fishing impacts on the size structure of coral reef fishes exploited by a predominant gear type in Northeastern Brazil, establishing a baseline for future monitoring of fishing impacts and contributing to the development of sustainable fisheries management strategies. • Fishing negatively affected the size of reef fish assemblages of the Atlantic. • Vulnerable species must be prioritized in management initiatives. • Fisheries management must aim at maintaining the diversity of functional roles. [ABSTRACT FROM AUTHOR]

Recreational fishing is the fastest growing sector in industrialized nations and can have substantial impacts on marine fish populations and ecosystems. Commercial objectives are typically characterized by maximizing yield and fishery stability whereas recreational anglers generally prefer sustained access to fishing and the availability of larger fish. Achieving these objectives while balancing tradeoffs between recreational and commercial fishing is essential to effective recreational and mixed-use fisheries management. Balancing multiple sector objectives is of particular concern in the southeast United States (US), where recreational fishing is the dominant source of mortality for marine fish stocks. We developed and applied a size-structured management strategy evaluation (MSE) tool, individually, to two stocks in southeast US Atlantic waters, black sea bass (Centropristis striata), a sedentary reef fish in overfished condition, and cobia (Rachycentron canadum), a migratory coastal pelagic fish, to evaluate the performance and tradeoffs of mixed management procedures against a variety of objectives. Several recreational and commercial objectives were aligned: fishers sought to conserve the stock and maximize catch, which simplified the evaluation of tradeoffs. We tested management procedures over alternate states of recruitment for black sea bass, and natural mortality for cobia. Management procedures that allowed harvest for black sea bass resulted in or risked an overfished status if the current weak recruitment regime continues, but could rebuild with no fishing regardless of recruitment state. Although results were sensitive to uncertainty in recruitment, no management procedures could achieve historic landings for either sector, and only management procedures that reduced effort consistently resulted in a reduced number of dead discards. No management procedures resulted in an overfished status for cobia. Management procedures for cobia generally achieved objectives and were robust to uncertainty in natural mortality. In both case studies, tradeoffs occurred between maximizing catch and season length and maintaining a stronger size structure in the population. This study resulted in a flexible MSE tool with strong potential utility for scoping management procedures that explicitly consider recreational fishing objectives. [ABSTRACT FROM AUTHOR]

Yellow squat lobster fishery is one of the most important extractive activities in the central zone of Chile that occurs between 100 and 300 m deep. One of the difficulties in the management of the fishery is the high variability of the indices of abundance, which depends on the spatial distribution of the resource, among other things. Given the limited knowledge of spatial distribution patterns and spatiotemporal changes in yellow squat lobster density and biomass, the information collected during trawl survey assessments between 1999 and 2019 in central Chile was analyzed. Using the criteria of presence, persistence, distance, and discontinuity, 23 areas of aggregation between 26°42′ and 36°54′ S were identified and used to model the catch per unit area by a generalized additive models. The model explained 21.4% of the deviance and allowed us to show the population growth from 2001 onward between the regions of Valparaíso and Biobío, which was consistent with the extractive closure implemented by the managers from 32°10'S to the south. Most of the biomass of Cervimunida johni (∼75% of the biomass) was located in the Coquimbo, Puerto Oscuro, La Ligua, Valparaíso, Pichilemu, and Biobío aggregations, corresponding to 57% of the total surface where the resources were distributed. The present work provides information on the places that have been persistently occupied by Cervimunida johni , suggesting to managers an evaluation of the spatial limits that are currently being used in the surveys and their influence on the performance of the population evaluation model. [ABSTRACT FROM AUTHOR]

Marine protected areas (MPAs) have been proven to protect sessile organisms and territorial commercial fish successfully. These areas may also protect populations of commercial lobster species, many of which are both nomadic and resident. The potential effects on lobster ecology and management have been studied in several MPAs established for given species of lobsters or that include lobsters in their protected zones, including commercial clawed, spiny, and slipper lobsters. Some studies have shown the positive effects on lobsters within MPAs, such as increased abundance, density, biomass, catch-per-unit-effort (CPUE), and size. These outcomes may also benefit lobster fisheries because the MPAs can supply propagules, juveniles, and adults via the "spillover" process to unprotected areas. Some MPAs have even demonstrated that reduced fishing areas from MPA designation significantly increase total catch after several years of protection. Such MPAs can also benefit other industries, such as marine tourism and fisheries of other commercial species. Some reserves fail to show positive effects, perhaps due to factors such as MPAs that are small relative to the home ranges of lobster species, location, size, shape, protection of lobster predators, ineffective policing of illegal fisheries, and "edge effects". Factors for successful MPAs include being a "no-take" zone, adequate enforcement, size, shape, and age of the reserves. Additional factors are proper MPA location for larval recruitment, suitable habitats, absence of anthropogenic disturbance, and full participation of the affected community, including the fisheries industry. Controlled before-and-after studies that explore the biological and fishery impacts of MPAs on surrounding fisheries are scarce but needed to assess the value of MPAs in fishery management. In view of dwindling of some lobster populations and possible conflicts between conservation scientists and fishermen, long-range studies of lobster populations inside and outside of MPAs and engaging all stakeholders are imperative. • Marine protected areas (MPAs) conserve lobster populations, sometimes boosting their fisheries. • MPAs increase the abundance, density, biomass, and size of lobsters. • The conservation benefits are established for several species of clawed, spiny and slipper lobsters. • Location, size, shape, and species ecology are important for MPA efficiency. • The success of MPAs depends on the full participation of affected communities. [ABSTRACT FROM AUTHOR]

Surplus production models (SPMs) have a long history in fisheries ecology and are important for the assessment and management of marine species and stocks. However, the implementation, application, and usage of these models vary across regions and case studies. Good practice guidelines can streamline modelling workflows, inform the acceptance or rejection of an assessment, and facilitate the derivation of management advice from accepted assessments. This paper discusses current practices in the application of SPMs and proposes good practice guidelines for their use in stock assessment. We complement our recommendations with results from a simulation study examining the performance of an age-based operating model and a SPM assessment model under 60 scenarios with various assumptions regarding data quantity, quality, and model priors. We provide specific good practice guidelines for two widely used state-space SPMs: SPiCT and JABBA. Finally, we discuss current limitations and suggest avenues for future developments for SPMs. • Discussion of input data and priors for surplus production models. • Simulation study reveals strengths and limitations of SPMs regarding input time-series length, contrast in data, and priors. • Considerations regarding management advice derived from surplus production models. • Outline of and recommendations on future research regarding surplus production models. • Good practice guidelines for the application of surplus production models and their use to derive robust management advice. [ABSTRACT FROM AUTHOR]

Marine fishes are heterogeneously distributed across their ranges according to population dynamics governed by complex spatiotemporal relationships between ontogenetic habitat usage, species interactions, environmental variability, and harvest patterns. However, few stock assessments incorporate spatial population structure in the determination of population status and sustainable catch limits. A small number of generalized stock assessment software platforms are utilized worldwide to assess a large number of marine fish populations. Although each platform relies on similar underlying population dynamics, the spatial capabilities and functionality often differ among them. We catalogue spatial dynamics and capabilities across stock assessment platforms to leverage collective experiences and identify future needs for next generation assessment software packages. Despite commonalities across platforms (e.g., most models allow for a single population with spatial heterogeneity, apportionment of recruitment, and age-varying connectivity), no single platform is flexible enough to address the full breadth of spatial dynamics observed for managed marine fish species. Our review clarifies spatial assessment design and modeling 'good practices', while emphasizing the need for more generalizable and modular next generation assessment platforms that can account for the spatiotemporal complexity of marine resources (such as natal homing and spawning migrations, ontogenetic movement patterns, metapopulation structure, and complex fleet dynamics). Generalized, spatially-integrated assessment platforms will be key decision-tools to account for spatiotemporal species and fishery interactions, particularly as managers attempt to address climate change and implement ecosystem-based fisheries management. • Changing distributions and other scale-dependent management challenges require advancements to stock assessment software tools. • Despite some commonalities across assessment platforms, none were flexible enough for the full extent of observed spatial population dynamics. • Population structure, recruitment, and connectivity parameterization options were the most varied and are areas for cross-collaboration. • Challenges include multiple population structure hypotheses, parameter dimension constraints, and efficient management and review systems. • Spatial layers (partitions or strata) should be a foundational feature of any future generalizable, modular software development approach. [ABSTRACT FROM AUTHOR]

Understanding of factors that explain variation in potential fisheries yields is essential for the ecosystem-based management of lake fisheries. We used mark-recapture and Nordic survey net sampling to obtain estimates of Eurasian perch (Perca fluviatilis) abundance in 28 small (13.3 ha ± 11.4 ha, mean ± S.D.) boreal lakes. A size-structured population model was calibrated for each lake using further individual data to derive estimates of potential yields. Principal component scores formed from physical and chemical environmental parameters and a simple score reflecting the relative photic area of the lakes were then used to explain variation in theoretical yields to identify potential environmental proxies for fisheries management purposes. The estimated mean biomass of perch in the study lakes was 52.4 ± 51.2 kg ha−1, and the maximum sustainable yield, obtained with environment-dependent recruitment size was estimated to be 9.4 ± 12.1 kg ha−1 yr−1. The estimated yields were highest in shallow lakes with good oxygen saturation and with high percentage of euphotic bottom while excess nutrients decreased yields and alkalinity was marginally predictive for catch of large individuals. Our study provides quantitative estimates of potential yields of varyingly sized perch and helps to develop environmentally informed management for small lakes of which some are surprisingly productive. • Sustainable yields of Eurasian perch were evaluated for 28 boreal lakes. • Reversed type II functional response was used to predict abundance from CPUE • Primary nutrients showed a bell-shaped curve with sustainable perch yields • Shallow lakes with good oxygen saturation showed the best predicted yields • Relative surface area of euphotic bottom offers a simple indicator of high yields [ABSTRACT FROM AUTHOR]

Fisheries management operates under uncertainty, often driven by the dynamic nature of marine ecosystems and associated fisheries. Stock assessment models, which form the scientific basis of decision-making in fisheries management, strive for realistic representations of biological and fishery processes. However, data limitations and knowledge gaps necessitate simplifying assumptions for representing these complex bio-socioeconomic systems, which can increase uncertainty in the assessment process. Addressing time-varying fishery dynamics (i.e., due to regulatory changes or alterations in harvester behavior) is a common and particularly challenging problem for stock assessment models. Time-varying fishery selectivity is widely utilized to address changes in fishery dynamics but may not be adequate when regulatory changes substantially alter gear usage and associated assessment fleet structures. We explore the implications of accounting for, or ignoring, complex temporal changes in fleet structure and selectivity within stock assessment models by utilizing a recent and high-value case study, Alaska sablefish (Anoplopoma fimbria). Our findings demonstrate that the treatment of fleet structure (i.e., adding fleet complexity to account for gear transitions) did not greatly influence estimates of spawning biomass trajectories. However, associated selectivity assumptions had substantial impacts on sustainable harvest recommendations. We recommend that the treatment of fleet structure and associated selectivity assumptions should incorporate a priori considerations and subject-matter expertise of fishery and biological dynamics to ensure pragmatic and appropriate model parameterizations. Moreover, we advocate for multi-fleet models as a useful diagnostic tool for validating model estimates from single-fleet assessments when uncertainty in fleet dynamics exist. [ABSTRACT FROM AUTHOR]

Fish ageing is a vital component of fisheries management as it enables the evaluation of fish population status and supports the development of sustainable management strategies. However, traditional methods of age determination through otolith analysis by experts are resource-intensive and time-consuming. Therefore, there is a growing demand for more cost-effective and automated techniques to accurately determine fish age. In accordance with this purpose, we proposed a multistage framework for fish age prediction using otolith images. First, otoliths in the images were detected using the Faster Region-based Convolutional Neural Networks (RCNN) model, which includes 8 convolution layers, and the detected otoliths were clipped. Subsequently, using a pre-trained neural network based on the transfer learning approach, deep features were extracted separately from the right and left otolith images, and all the obtained features were combined. Finally, these combined features are given as input to the Gaussian process regression model. To evaluate the performance of the proposed architecture, 4109 images of right and left otoliths belonging to Greenland halibut (flatfish, Reinhardtius hippoglossoides) were used. The proposed architecture produced 1.83 MSE, 0.98 R-squared, 1.35 RMSE, and 10.29 MAPE scores in the experimental studies. As a result, the proposed model achieved superior performance compared with previous studies. Our findings show that our FishAgePredictioNet system could help experts predict fish age based on otolith images. [ABSTRACT FROM AUTHOR]

Oceanic squids have distinct population dynamics and life histories compared to most fishes, necessitating tailored fishing and management strategies. To conserve and sustain oceanic squid stocks, the Chinese government has implemented seasonal high seas closures from September 1st to November 30th each year since 2020. Our study aims to evaluate closure efficacy for oceanic squid conservation using the central-eastern Pacific closure as a case study and propose targeted improvements. Based on biological data from equatorial waters in two selected periods (before closure: December 2017 to May 2018; and after closure: December 2021 to May 2022), comparative analyses of mantle length distribution and length at maturity (L m) were used to detect the differences before and after closure for the jumbo squid Dosidicus gigas. Based on biological data from 2009 to 2022, a three-dimensional environment-based general additive model (GAM) was applied to predict the intermonthly distribution of spawning grounds. Comparison analyses indicated increased mantle length and L m following closure. The best-fitted GAM explained 38 % of the deviance. Environmental factors significantly influenced gonad development. Model predictions recognized seasonal core spawning grounds at the Costa Rica Dome and Cocos ridge plus year-round secondary spawning grounds off the Pervian-Chilian waters south of 8 ° S. The current closure protects overlapping feeding grounds and migratory routes for the Costa Rica Dome and Peruvian coastal spawning groups, while Peruvian-Chilian waters south of 8 ° S also represent similar grounds for the Peruvian coastal and Chilean groups. Overall, seasonal closures could have a positive conservation effect on oceanic squids. Maintaining the current closure delayed or advanced 1 month alongside another closure off the southern Peruvian EEZ from October to December or November to January could further enhance jumbo squid conservation [ABSTRACT FROM AUTHOR]

Many of the world fisheries, especially small-scale fisheries, are in data-limited situations, for which proxy Biological Reference Points (BRPs) derived from per-recruit analyses are widely used to inform fisheries management. However, due to limited information on stock recruitment, per-recruit analyses usually assume constant recruitment and the influences of this key assumption have not been fully understood. In this study, we combined per-recruit analyses and stock-recruit relationship to build equilibrium models for eight species with different life history traits, and used the management strategy evaluation (MSE) framework to assess the uncertainty of proxy BRPs in achieving fisheries sustainability. Our results showed substantial variations in the performances of proxy BRPs on maintaining yield and biomass, and even conservative BRPs, e.g. F 0.1 caused overexploitation in half of the cases (4 out of 8). The divergence of the performance between proxy BRPs and F MSY could be substantial, depending on steepness of stock-recruit relationships (correlation ranged from –0.55 to 0.9 for yield, and 0.53 to 0.96 for biomass). Accordingly, we presented an empirical approach for remediation, using correction coefficient to adjust the traditional proxy BRPs. The empirical approach showed satisfactory performances in the validation processes with an independent dataset. This paper demonstrates that proxy BRPs may introduce risks in achieving fisheries sustainability, whereas the errors can be readily adjusted with empirical estimates of steepness for most data-limited fisheries. [ABSTRACT FROM AUTHOR]

Statistical catch-at-age assessment models used for fisheries management integrate multiple sources of information that are statistically weighted in a joint likelihood framework; the relative statistical weighting between these sources of information is an important, yet often subjective aspect of stock assessment. Input sample size (ISS) is a quantity that is used to statistically weight composition data in these types of models. Both design-based bootstrap and model-based estimators have been proposed, however, these methods to determine ISS do not explicitly account for uncertainty from ageing error and growth variability that are inherent to expanded age composition and conditional age-at-length data. In this study, we evaluate the impact of including ageing error and growth variability within bootstrap methods that estimate age composition and conditional age-at-length ISS. We find that for all the stocks evaluated the ISS determined from bootstrap methods decreased as these addition sources of uncertainty were included. The decrease in ISS was species type specific, but generally decreased up to 40% when ageing error was introduced, up to 50% when growth variability was included, and up to 60% when both sources of uncertainty were included. These results indicate that there is more variability within age composition or conditional age-at-length data than would be accounted for with ISS estimates that do not include these sources of uncertainty. The method and results provided here allow for assessment scientists to statistically weight age composition and conditional age-at-length with ISS that takes into account ageing error and growth variability from either fishery-independent or fishery-dependent sources. Including these sources of uncertainty improves bootstrap estimates of ISS to capture all the sources of variability in age composition and conditional age-at-length and will subsequently improve stock assessment model quality. • Ageing error and growth variability was integrated into a bootstrap framework to estimate input sample size. • Incorporating ageing error and growth variability reduces the input sample size up to 60%. • The magnitude of reduction in age composition and conditional age-at-length input sample size was species type specific. • Incorporating ageing error and growth variability accounts for additional sources of uncertainty in composition data. [ABSTRACT FROM AUTHOR]

Marine fish species that form spawning aggregations are often vulnerable to exploitation, such as the European bass (Dicentrarchus labrax). Information on bass spawning aggregations is not well resolved temporally and spatially. Otolith daily growth increment (DGI) counts were conducted on 0-group bass collected in July-August 2014 & 2019 from seven settlement estuaries in the Irish and Celtic seas, to estimate the timing of spawning. These timings parameterised three-dimensional hydrodynamic and Lagrangian particle tracking models, run in reverse, to identify probable spawning locations. Estimated spawning occurred between April-May (inshore and offshore) < 200 km from each settlement area. At least two broad spawning areas were predicted: the central Irish Sea that led to post-larval recruitment in north Wales and northwest England, and the southern Irish Sea/Celtic Sea that led to post-larval recruitment in south Wales. Results indicate the current seasonal closure for northern stock bass may not protect spawning events that drive recruitment into settlement sites in Wales and northwest England. Surface temperatures and wind- and tide-driven surface currents determined the connectivity between spawning and settlement sites. Atmospheric drivers are expected to change in the future and management needs to account for potential regional shifts in spawning times and locations. • Otolith daily growth increments counted from post-larval bass from 7 nursery sites around the coast of Wales, UK. • Spawning events calculated between April-May in 2014 and 2019. • A three-dimensional ocean particle tracking model was run in reverse. • Two likely broad spawning areas identified providing bass larvae into Welsh nursery areas. • Connectivity between spawning and settlement sites discussed in context of surface temperatures and wind- and tide-driven surface currents. [ABSTRACT FROM AUTHOR]

Cost-effective fishery-independent surveys are critical for obtaining high-quality data to support stock assessment and fisheries management. Classical probability-based sampling designs may exhibit limitations in spatial coverage and flexibility. Spatially balanced sampling (SBS) designs offer the ability to efficiently distribute sampling stations across a survey area. This study evaluates the performance of SBS designs in multispecies fishery-independent surveys through simulation studies, involving two widely used classical sampling designs (Simple Random Sampling and Stratified Random Sampling) and two SBS designs (Generalized Random Tessellation Stratified Model and Balanced Acceptance Sampling). The aim of the simulation study was to assess the performance of different sampling designs in estimating the abundance index for four target fish species across different seasons. The results showed that SBS designs had relatively high accuracy and precision in terms of relative estimation error, relative bias, and coefficient of variation. Among the four sampling designs, the Generalized Random Tessellation Stratified Model performed optimally at the same sample size. In conclusion, this study suggests that SBS designs can enhance the precision of abundance index estimation for different fish species. Given its ability to effectively distribute sampling stations and its flexibility, a better understanding and application of SBS designs in fishery-independent surveys are warranted. • SBS designs showed higher accuracy and precision than classical sampling designs. • The GRTS model was optimal among four sampling designs with same sample sizes. • SBS designs can enhance the precision of abundance index estimation for different fish species. • Further understanding and application of SBS designs are needed in fishery-independent surveys. [ABSTRACT FROM AUTHOR]

It is the exceptionally rare case one can directly and with little uncertainty measure fish absolute abundance through many stock generations in all areas of a stock's range. Instead, we often seek "gold standard" stock assessments—models that use catch, abundance indices and biological compositions to produce precise and unbiased indicators of stock status for management use. Unfortunately, data and resource limitations affect our ability to collect all the desired information and apply methods with low uncertainty in the results. To confront this challenge of poorly informative data and low resource situations, a host of analytical approaches have been developed to engage the power of fisheries science to inform management decisions despite limitations. These methods are numerous and often challenging to understand and navigate, despite being simplified (though not simple) approaches. It is important to understand where these methods come from, how they can be used, and how to evaluate them. Often they are presented as alchemically providing golden outputs despite heavy assumptions and impure inputs. Here I aim to provide both scientific context of and guidance in organizing and applying so-called data and resource limited stock assessments. I offer a list of best practices by presenting fundamental principles of modelling and highlighting leading edge tools for organizing and conducting analyses under a variety of constraining conditions, offering a conceptualization of stock assessment expressing the interconnectedness of each method and how those can be largely unified under a common modeling framework. The concept of a stock assessment continuum is described, along with discrete examples in the form of a decision tree outlining the major modelling groups for a large variety of data availability scenarios. The basic approach to applied fisheries science and management is presented as interpreting uncertain model outputs (i.e, indicators) using reference points that can then be linked to management decisions via control rules that should express risk tolerance to meeting management objectives in light of uncertain outcomes. The role of simulation testing of management procedures is highlighted in order to evaluate robustness to uncertainty. While more and better data should be a focus of any management system, there is no excuse to wait for golden outputs. We have the tools and theory ready to help direct management of data and resource limited stocks now. [ABSTRACT FROM AUTHOR]

In fisheries management, the L 50 is a commonly-monitored reproductive trait reflecting the sex-specific length (L) at which 50% of the fish are expected to exhibit developing gonads near the spawning period. Although different methods exist to estimate the L 50 , it is often obtained from a binomial generalized linear model (GLM) fitted with a logit link. To provide reliable parameter estimates for the production of the ogive from which the L 50 is obtained, the logit link must be correctly specified, a prerequisite that is not always verified nor true. To identify the most-likely ogive, adequacy tests allowing to detect a lack-of-fit or any link misspecification should ideally be applied to competing binomial models that also consider alternative links, such as the probit and complementary log-log (cloglog). Because multiple estimates are often compared, their uncertainties should also be adequately quantified to detect any potential change, but no consensus exists about the method offering the best coverage probability. Here, we used a large-scale dataset of 23,681 walleye (Sander vitreus) females sampled in 90 harvested populations over two decades in Québec, Canada, to first estimate the L 50 uncertainty under different simulation scenarios to identify the most accurate method regarding nominal coverage. Then, of 46 populations sampled in two different surveys, we assessed which link provided the best adequate estimation for each survey-specific L 50 and used associated 84% CIs to determine if a change occurred based on whether they overlapped. The influence of gonad data characteristics on L 50 uncertainty was also examined before assessing between-survey L 50 variation with competing GLMs as an alternative approach. The analysis of the simulated data indicated that the Monte Carlo approach with bias-corrected and accelerated (BCa) interval offered the best coverage probability. The empirical analyses revealed that the probit was the most often adequate link to estimate the L 50 , followed by the cloglog, whereas the logit ranked last. When controlling for sample size, the level of L 50 uncertainty increased with the percentage of overlap in length between walleye females with (1) and without (0) developing gonads, whereas it progressively decreased as the percentage of 1's in the sample increased to then inversed, indicating that more balanced binary data yielded less L 50 uncertainty. All analyses revealed that for a "true" or estimated effect size of ≤ 10%, the survey-specific 84% CIs often overlapped despite statistical support for a difference found in the best-supported GLM comparing both surveys. Overall, our study indicates that many analytical considerations, from gonad data structure characteristics, model adequacy assessment, up to how the L 50 uncertainty is quantified and compared, need to be accounted for to achieve more reliable statistical inferences regarding the observed variation in this reproductive trait. [ABSTRACT FROM AUTHOR]

The Indonesian deep-slope demersal fisheries are economically valuable and contribute to the wellbeing of millions of people. However, the sustainability of these fisheries is uncertain because they lack data and assessment. As a precursor to management, we developed and applied a framework for using standardized catch per unit effort (CPUE) and spawning potential ratio (SPR) as indicators to assess eight primary species-fishing gear complexes: the Malabar blood snapper Lutjanus malabaricus (droplines and longlines), goldbanded jobfish Pristipomoides multidens (droplines and longlines), sharptooth jobfish P. typus (droplines and longlines), crimson snapper L. erythropterus (droplines), and rusty jobfish Aphareus rutilans (droplines). We standardized CPUE by identifying relevant fishing trips using a species-association approach and removing any changes in the index not attributable to abundance by using a delta-generalized linear model. SPR values were estimated on a per-recruit basis from life-history parameters using length data. Results indicated that in 2020, all stocks were unhealthy (SPR values < 25%) with only a few exceptions (e.g., P. multidens and L. erythropterus). Most fishing grounds with low SPR values had stable or decreasing CPUE trends, suggesting that current fishing rates are suboptimal or unsustainable. However, L. erythropterus had an increasing CPUE trend but moderate to low SPR, indicating that fishing pressure has decreased so SPR may be an underestimate, leading to an optimistic but uncertain conclusion about stock health and the sustainability of current fishing rates. Such discrepancies between CPUE and SPR may be challenging for the implementation of management measures, but we have outlined and applied a framework for interpretation. The most recent yield values set by the Indonesian Ministry of Marine Affairs and Fisheries for these stocks, however, are 1.4–2.4 times higher than our calculations. This discrepancy may be attributed to several factors, such as inclusion of species that are atypical for deep demersal fish stocks in the Ministry's estimates, differences in methods or the types of data used, or annual variability. [ABSTRACT FROM AUTHOR]

The choice of assessment technique for a fishery with some, but not large amounts of data (intermediate data fishery), can be complex and depends on their suitability to the available data set(s) at an optimum resolution and appropriateness of model assumptions. Various "appropriate" techniques may have different output biases and understanding these is essential for robust fisheries management. We tested the suitability of an extended depletion model to assess a crustacean population using simulated data that replicated fishing patterns of a southern rock lobster (SRL) fishery in Western Australia. This simulation showed the model was appropriate for use and robust to assumptions including predetermined parameter choice and whether lobsters moulted during the fitted period. Although natural mortality was shown to have the biggest influence on model outputs (when compared to assumptions on moulting and fishing efficiency), its actual impact was minimal. When applied to the SRL resource off Western Australia, the model indicated that the stock has been heavily fished and reduced to almost 20 % of virgin levels. In recent years exploitation rates have declined due to external factors such as market access. This has resulted in a rapid increase in biomass, and model projections suggest that, with current catches, the biomass will return to 50 % of virgin levels within 10 years. Testing the modelling approach on a fishery with intermediate data provisions through simulation, has provided confidence in applying this technique to derive improved estimates for management. [ABSTRACT FROM AUTHOR]

The advance of ecosystem-based fisheries management worldwide has made scientific advice on fisheries related questions more complex. However, despite the need to take interactions between fish stocks, and between stocks and their environment into account, multispecies and ecosystem models are still hardly used as a basis for fishery advice. Although reasons are numerous, the lack of high-level guidance for target-oriented skill assessments of such models contributes to the mistrust to use such models for advice. In this study, we propose a framework of guiding questions for a pragmatic and target-oriented skill assessment. The framework is relevant for all models irrespective of their complexity and approach. It starts with general questions on the advice purpose itself, the type of model(s) and data available for performance testing. After this, the credibility of the hindcasts are evaluated. A special emphasis is finally put on testing predictive skills. The skill assessment framework proposed provides a tool to evaluate a model's suitability for the purpose of providing specific advice and aims to avoid the bad practice of incomplete skill assessments. In the case of multiple models available, it can facilitate the evaluation or choosing of the best model(s) for a given advice product and intends to ensure a level playing field between models of different complexities. The suite of questions proposed is an important step to improve the quality of advice products for a successful implementation of ecosystem-based fisheries management. • Lack of high-level guidance for skill assessments contributes to the mistrust to use more complex models for fisheries advice. • A framework of guiding questions for a pragmatic and target-oriented skill assessment is proposed. • The framework intends to ensure a level playing field between models of different complexities. • The framework is an important step for a successful implementation of ecosystem approaches to fisheries management. [ABSTRACT FROM AUTHOR]

Effective spatial fisheries management requires a proper understanding of the spatial distribution of both target species and discards. Also, spatial modelling of fishery-dependent data is an effective tool to capture uncertainties in data-limited situations. This study analyses the drivers behind discarding by comparing the standardising properties of three different components: Total Discards, Discards Per Unit of Effort and Total Discard Ratio. These metrics were analysed by means of Bayesian hierarchical spatio-temporal Gamma regression models to correctly to identify areas with high discards values that are characterized as discards hotspots. Our results showed that Total Discards is the component which better quantified the aggregated ecological impact of discarding practices, whereas Total Discard Ratio and Discards Per Unit of Effort identify complementary issues of benefits versus loss of biomass. Spatial maps obtained by combining these three approaches are a powerful tool for the spatial management of discards. [ABSTRACT FROM AUTHOR]

Conditionally autoregressive (CAR) space-time models have wide applicability because spatial association structure can be captured through an adjacency matrix, without expressly relying on distance information. However, in the traditional spatio-temporal CAR (STCAR), the adjacency matrix is based on adjacency relationships, which can be problematic in practical applications where those relationships are dependent on non-spatial considerations. A new formulation of a parametric structure for the adjacency structure was developed, offering a functional and flexible solution to this problem. This method is applied to estimate bigeye tuna catch for the purse-seine fishery in the eastern Pacific Ocean for 2020–2021. During the COVID-19 pandemic, collection of some data types for this fishery was severely negatively impacted, resulting in non-random loss of data. To mitigate this, a STCAR model was developed, combining multiple sources of spatio-temporal data to obtain enhanced prediction results. The objective was to produce statistically similar catch estimates to the historical time series on which current fisheries management is based, thereby minimizing bias due to a change in estimation methodology. The traditional CAR formulation assumes uniform weight in defining spatial dependence between neighboring areas when they share boundaries or corners, and no weight when the areal units do not share boundaries or corners. The new parametric approach uses expert opinions to define weighted adjacency in the formulation where the 'weight' is based on how substitutions rules apply when data is missing and areas can be 'adjacent' in terms of characteristics rather than simply spatially. The new parametric formulation of the adjacency matrix performed best, as compared to traditional formulations, was asymptotic as the parameter got smaller. This parametric specification of the adjacency matrix, along with an AR (1) structure in the STCAR, performed robustly when a sensitivity analysis was carried out by simulating non-random pandemic-like data-loss for pre-pandemic years. [ABSTRACT FROM AUTHOR]

The aim of the present study was to estimate age and growth of Cynoscion acoupa , using micro and macrostructures in otoliths and length frequency, in a sample of 255 specimens (13–107 cm in total length - TL) collected on the coast of the Maranhão State between 2007 and 2008. Validation of microstructures using alizarin dyes demonstrated daily deposition of microstructures whereas macrostructures were validated as annual according to monthly marginal increment analysis. A zone of daily microstructures from the core was observed in the otolith until 328 days (0.87 year) and after this zone, the first annual macrostructure was formed. There were no significant differences between growth of males and females using the von Bertalanffy model (VBGM), resulting in k = 0.13, L ∞ = 142.95 cm TL and t 0 = −0.45 year, with ages ranged from 0.3 to 10.2 years. The growth coefficient estimated by LFA was very high (k = 0.28). The results indicated that C. acoupa from the coast of Maranhão has a slow to moderate growth and high longevity, being able to exceed 14 years. Therefore, these parameters are important to understand the population dynamics, and should be considered to define management measures for C. acoupa. • Cynoscion acoupa shows daily and annual ring marking on the otoliths. • The daily rings can be seen and counted until the first annual mark (first year). • The growth of the species is considered moderate (k = 0.28). • Growth between males and females has no difference. [ABSTRACT FROM AUTHOR]

Changes to management of a fisheries resource are often required to ensure ongoing sustainability. However, such changes can sometimes lead to unintended effects such as increased release rates and associated post-release mortality. These effects may be highly variable between species and areas. Recreational fishing management changes were introduced on the west coast of Australia in 2009/10 to recover stocks of demersal scalefish. Key changes included reducing mixed species bag limits across management zones and increasing the minimum size limit for one species in some management zones. The restrictive catch limits resulted in increased release rates of key demersal species. However, whether such increases are significant and sustained over time, and thus of management concern, have not been evaluated. We carried out intervention time series analysis to evaluate the impact of management changes on release rates of four key demersal species for the recreational sector in metropolitan and regional management zones covering ∼8° latitude using an 18-year time series of charter recreational fishery data from July 2002 to January 2020. We observed varying responses in release rates by species and zones, the most common of which were a step increase, a ramp and a temporary increase that decayed. These responses may be related to targeted management changes which influenced fisher behaviour, perceived recreational value of some species and recruitment variation. Our study demonstrates that intervention analysis, which has seen limited use in this context, can assist in evaluating the impact of management changes on different species for recreational fisheries. [ABSTRACT FROM AUTHOR]

Bank- and boat-angler efforts are logistically difficult and costly to estimate, preventing landscape-scale estimates that are required to address current and future challenges (e.g., climate change, invasive species) for inland recreational fisheries. Using a large Nebraska, USA, recreational fishery dataset (N = 67 waterbodies), we demonstrate that waterbody size can be used to predict bank- and boat-angler efforts across a heterogeneous landscape of extra small (< 104 ha) and large (> 647 ha) waterbodies. Bank and boat anglers respond to waterbody size, however these relationships appear to be unique between the two angler types. Boat-angler efforts increased as a function of waterbody size, whereas bank-angler efforts increased as a function of waterbody size for extra small waterbodies but not for large waterbodies. The ability to connect waterbody size and angler effort will be important for continued effective inland fisheries management. • Quantifying bank and boat angling effort is often difficult and costly. • Thus, many waterbodies must be managed without angling effort information. • Waterbody size can predict bank and boat angling efforts at the landscape scale. • These relationships can guide future fisheries management decisions. [ABSTRACT FROM AUTHOR]

Discarding is major issue globally in terms of conservation, fisheries management and economics. To date, studies on fisheries discards have been primarily focused on large-scale fisheries and little attention was given to small-scale fisheries (SSF) discards. The multi-species and multi-gear nature of SSF in the Mediterranean makes any scientific effort to study discards and management action to regulate discards challenging. The study attempted, for the first time in Levantine Sea, to quantify discards, identify discarded species, and comprehend the causes and drivers of SSF discarding in Cyprus through 208 fishing trips by observing the fishers' regular fishing operations using trammel nets, gillnets, monofilament nets and bottom set longline. Out of the total catch, 1408.385 kg were landed and 956.581 kg were discarded. The majority of discarded individuals were non-indigenous species (73.7 %). Results exhibited a discard rate of 9.92 individuals (4.6 Kg) and a mortality rate of 0.86 per sampled fishing trip, indicating that almost all individuals discarded were released dead. The proportional discards rate (%) out of the total catch was calculated at about 41 % and the average landings/discards ratio in terms of weight was 1.5:1. The five most common discarded species in terms of numbers belonged to osteichthyes and were Sargocentron rubrum followed by Lagocephalus sceleratus , Torquigener flavimaculosus , Scorpaena scrofa and Pterois miles representing 27.8 %, 25.2 %, 13.9 %, 4.7 % and 2.4 %, respectively, of all discarded species. 'Poisonous fish', 'undersized fish' and 'low' and 'no commercial value' fish were the main reasons for discarding. Other reasons included 'prohibited' to land species, 'poor condition' and 'depredated' fish. Elasmobranchs were the second most abundant class accounting for 4.3 % of the total discarded taxa, including threatened, endangered and critically endangered species. Net length, soak time, gear type, and seasonality are the main factors driving discards. The findings of the current work could support the development of national fishery-specific management action plans to mitigate discards and impact on marine ecosystems. • On average, for every 1.5 Kg of landings there was 1 Kg of discards. • Non-indigenous species accounted for a large be part of the discard fraction. • Mortality rate of discarded individuals is relatively high. • Net length, soak time, gear type and seasonality were the main drivers of discards. • Specific management measures are needed to increase fishing gear selectively. [ABSTRACT FROM AUTHOR]

The establishment of marine protected areas (MPAs) and the implementation of ecosystem-based fisheries management (EBFM) are often hampered by limited spatial information of target species, such as their optimal distributional range and habitat suitability, which varies with life history stage. Neglecting these ontogenetic variations may lead to biased predictions in species distributions. In this study, Joint Species Distribution Models (JSDMs) were constructed using Bayesian ordination and regression analysis (Boral) to assess the effects of ontogenetic variation on species interactions identification and spatio-temporal distribution prediction of 10 major fish species in the central and southern Yellow Sea. Individuals of each species were classified either as juveniles or adults, depending on their length at maturity. Our results reveal that spatial distribution, species interactions, and habitat suitability vary with life history stage for each species. JSDMs incorporating partitions for life history stage performed better than those excluding them, as evidenced by lower RMSE and higher R2 values. Therefore, we suggest that classifying species by life history stage may infer inter-species interactions as well as address the effects of ontogenetic habitat shifts on species distributions. Through this study, we highlight the importance of the impact life history stage has on fish species interactions and their spatio-temporal distributions, which can be used to provide guidance for the construction of MPAs and the spatial management of fisheries resources. [Display omitted] • Impact of life history stages on species interactions and distributions were evaluated using JSDM. • JSDMs incorporating life history stages classification had better performance. • All species showed evidence of variation in species interactions and distributions among life history stages. • The process of ontogenetic partitioning facilitates the resolution of habitat and interaction shifts of species. [ABSTRACT FROM AUTHOR]

The aim of this case study was to assess potential temporal and spatial differences in productivity measures of vessels operating in the Queensland spanner crab fishery. This fishery's logbook records of catch and effort data allowed analysis of the impact of fishery management changes on productivity measures. Data envelopment analysis (DEA) with a 'window analysis' approach was used to derive estimates for measures of technical efficiency, capacity utilisation and scale efficiency over time for five different spanner crab fishing regions. The results suggest that average technical efficiency and capacity utilisation were relatively low over time and across fishing regions, implying a high level of technical inefficiency and the existence of excess capacity in the fishery. Scale efficiency was found to be high historically but decreased slightly since 2006 for all regions. The results suggest that this decline is likely not caused by the fishery management changes, but instead is due to other factors. Additional data (e.g., revenue, profit, costs, skipper experience) and analysis is needed to assess the causes for the low technical efficiency and capacity utilisation and reasons for the decrease in scale efficiency as a baseline for specific fishery management recommendations. The study shows that temporal and spatial efficiency and productivity analysis of fisheries can help identify potential issues that are not otherwise apparent. • Spatial/temporal efficiency analysis to inform fishery management. • Low technical efficiency indicates underutilised variable inputs in all five regions. • Low capacity utilisation across the fleet implies underutilised fixed inputs. • Scale efficiency was historically high, but decreased since 2006 in all fishing regions. • Lack of data to explain low fleet efficiency performance needs to be addressed. [ABSTRACT FROM AUTHOR]

The green abalone (Haliotis fulgens) represents an important artisanal fishery in the Northwest Pacific in Mexico but with populations below the optimum recovery level. Illegal fishing and the potential impact on wild populations because of the stock enhancement programs would benefit from a genomic tool to discriminate among populations and provide traceability. In this study, SNP panels for green abalone were developed from ddRad-seq data and used to evaluate individual assignment accuracy at two hierarchical scales. One included three genetic groups: 1) Guadalupe Island (GI), 2) Northern Coastal Group (NCG) and 3) Southern Coastal Group (SCG); and the second only the two coastal groups. Eight SNP panels (from 50 to 1000 loci), with markers ranked by F ST , were evaluated to assess the power to identify individuals from the three genetic groups at both scales. The predictive model found high discriminatory power for almost all the SNP datasets for two of the three groups (GI and SCG), ranging from 0.72 (s.d. = 0.32) to 1. At the coastal scale, assignment accuracies for NCG individuals varied substantially with the number of SNP markers, ranging from 0.01 (s.d. = 0.05) with the 50 most informative SNPs to 0.79 (s.d. = 0.30) using 1000 SNPs. These SNP panels will provide genetic tools for tracing the origin of green abalone in the food-supply chain, which will assist fishing cooperatives in certifying their products and tackling illegal fishing in México. [ABSTRACT FROM AUTHOR]

Under long-term fishing pressure, the biological traits of many wild fish populations have changed. Such phenotypic changes include smaller in size and earlier age-at-maturation, strongly suggesting that fishing could induce rapid changes in the life-history traits of fish. However, whether extensive fishing will lead to genetic changes in fish, how they occur, and whether they are reversible still requires further research. In this study, we analyzed biological traits of marine medaka (Oryzias melastigma) subjected to 50% experimental harvest for 4 consecutive generations. This study adopted a factorial design with three size-selective harvesting strategies (large-, small-, and random-size selection) on groups either before or after maturation. We compared the growth, maturation, and early life stages of marine medaka for different harvesting strategies. The results showed that the mean lengths and mean weights in large-harvested populations significantly declined after 4 generations, whereas small-harvested populations did the opposite. Furthermore, selective harvesting of large individuals also led to earlier maturation, declining fecundity, declining hatching rate and increasing larval mortality. Importantly, compared to harvesting before maturation, harvesting after maturation could mitigate the effects of harvest on biological traits. This study provided experimental evidence for the impact of selective harvest on phenotypic evolution and contributed to the theoretical basis for sustainability in fisheries and fishery management. • Large-selective harvesting can increase larval mortality and decrease body size. • Size-selective harvesting can lead to early maturation and a low hatching rate. • Fishing after maturation could mitigate the effects of the harvest on the traits. [ABSTRACT FROM AUTHOR]

Potential and emerging fisheries create challenges and opportunities for fishery managers who need to decide how to sustainably manage a fishery that does not yet exist. A new Pacific hake stock off the west coast of Mexico has been identified. The Mexican government is interested in assessing the feasibility of a new commercial fishery. This work proposes and analyzes alternative potential fishery management measures for this possible new fishery under biological and market uncertainties. Results indicate that a new fishery could be biologically sustainable and economically profitable under a set of management strategies and control rules. A limited access strategy with low effort is recommended because it is most profitable per vessel and biologically cautious, considering the high uncertainty associated with the exploitation of an unfished stock. Despite the combination of high operating costs and low prices the fishery could still be profitable in the long-term, although there is risk of overexploitation if high fishing effort is allowed. Nevertheless, our results suggest low risk of fishing down the dwarf hake stock if the fishery is managed under low effort levels, allowing for sufficient opportunities for data collection and adaptive management. This work addresses the rare opportunity of assessing a fishery previous to its operation, with all the associated data limitations and uncertainty. [ABSTRACT FROM AUTHOR]

Size-spectrum models are good candidates to examine the effects of fishery management because predation and fishing are largely body-size dependent. We examine the effects of increasing trawl fisheries' selectivity through the application of a size-spectrum model to a "continental shelf system" in the NW Mediterranean. This system is sustained by detritus, as background resource, and by benthic invertebrates that channel the energy to the fish community. The "continental shelf system" in our model consists of three components: 1) demersal and benthic fish and invertebrate species modelled by size spectrum dynamics, 2) carrion and 3) detritus. The model was able to exemplify the effects of changes in fishing patterns on the different biological components of the shelf system. According to the model outputs, in the short term the main target species, hake and red mullet, would be the main beneficiaries of the increased net selectivity and reduction of fishing effort. Discards reduction would have negligible effects. Despite the positive outcomes, this exercise was not exempt of challenges, mainly due to the data-demanding nature of the approach applied to a system with high diversity of life-histories and feeding strategies of invertebrate and fish species. And yet, our work is a first and crucial step to understand the size-spectrum dynamics of a continental shelf ecosystem subjected to fishery activities. [ABSTRACT FROM AUTHOR]

Many demographic processes vary by age and over time, but are also hypothesized to exhibit cohort-specific patterns in variation; accounting for this variation within fisheries management remains a key challenge for contemporary stock assessments. Although there is evidence for time, age, and cohort-specific patterns in the variation of various components within stock assessment (e.g., selectivity, growth), methods are sparsely documented or are lacking to simultaneously estimate autocorrelation over time, among ages, and by cohort while also quantifying residual variation. We demonstrate an approach that facilitates the simultaneous estimation of autocorrelation for time, age, and cohort correlations, and provide two options to estimate the pointwise variance of this process (termed conditional and marginal variance). Using eastern Bering Sea walleye pollock (Gadus chalcogrammus) as a case-study, we develop factorial model formulations to demonstrate differences in predicted weight-at-age values from models that estimate different combinations of correlation parameters along three axes (age, year, cohort). We show that traditional model selection tools can be used to identify the relative evidence for, and magnitude of, age, time, and cohort correlations, and demonstrate that this method can be easily integrated as a routine option within next-generation stock assessments. Code to replicate our analysis is provided in a GitHub repository (https://github.com/chengmatt/GMRF%5fWAA), and includes a Template Model Builder function for assembling the precision matrix to facilitate easy adoption in other software packages. • Demographic and fishery processes vary across ages, years, and cohorts. • We propose an approach to estimate partial correlations across ages, years, and cohorts with residual variation. • We use eastern Bering Sea walleye pollock as a case-study to illustrate the use of our method. • Assessment components suited to this approach include survival, maturity, growth, and fishing mortality (and selectivity). • Our method facilities the estimation of correlated processes in next-generation assessments [ABSTRACT FROM AUTHOR]

Monitoring the movements of fish enables management decisions to be based on the ecological requirements of the species in question. PIT tags are a cost effective, long-term method of tracking large numbers of fish. As this technology has improved, the size of PIT tags has decreased, enabling smaller species, and younger fish to be tagged and tracked. There is limited information available on the possible effects that these tags have on the survival rates and subsequent health of small fish. Swimming performance is a physiological measure that is easy to quantify in the lab and directly relates to an individual fishes health. We used swimming performance to assess the effect of microPIT tags (8.4 mm) on five small-bodied, and juveniles of five large growing native Australian fish species. In an initial trial to assess suitability for microPIT tagging, two of the small-bodied species had high mortality and were categorised as unsuitable for tagging. Sample sizes were increased for the remaining eight species to quantify potential effects of microPIT tags on swimming performance. For these eight species we found no significant effects of microPIT tags on their swimming performance. [ABSTRACT FROM AUTHOR]

Factors potentially affecting fish discarding were evaluated for species managed under the Gulf of Mexico grouper-tilefish individual fishing quota (GT-IFQ) program. Thirteen commercially important species are managed under the GT-IFQ program. Some of the more commonly caught species in the program include red grouper (Epinephelus morio), gag (Mycteroperca microlepis), speckled hind (Epinephelus drummondhayi), golden tilefish (Lopholatilus chamaeleonticeps), and blueline tilefish (Caulolatilus microps). It is necessary to determine why discards are occurring to develop a future discard mitigation strategy. Logistic models were constructed using data from the Southeast Fisheries Science Center's (SEFSC) Reef Fish Observer Program (RFOP) with covariates of fish length, available allocation, gear type, calendar year quarter, and year to infer reasons for discarding. The results from RFOP models in conjunction with self-reported discard information from the SEFSC Supplemental Discard Logbook program determined that discarding due to fish length selection, not related to minimum a size limit, is occurring for golden tilefish, speckled hind, yellowedge grouper (Epinephelus flavolimbatus), and snowy grouper (Hyporthodus niveatus). Other dynamics such as multi-species quota discarding are likely responsible for discards of blueline tilefish. Based on the results of the study, potential changes to the GT-IFQ program such as additional flexibility measures were identified as potential management strategies for decreasing discards. A similar approach to inferring why discarding is occurring could be used in the other regions for more effective management promoting long-term sustainability of valuable fisheries. [ABSTRACT FROM AUTHOR]

• Genetic diversity was highest in Tonle Sap Lake populations and were remarkably lowest in Vietnamese domesticated populations. • Populations were structured by habitat (lake and floodplain, wild and domestication). • Isolation by distance was detected at a regional scale but not found in local scales. Striped snakehead (Channa striata) has been cultured for several decades in Viet Nam while only recently cultured in Cambodia. A cross-country comparison of genetic diversity in wild and cultured striped snakehead populations provided novel insights for improved genetic resource management and cultivation in Lower Mekong region. We collected striped snakehead samples from three wild and three cultured populations in the Vietnamese Mekong Delta for comparison to samples from eight wild populations in Cambodia (n = 5 and 3 from Tonle Sap Lake and Mekong River floodplain, respectively). Sequencing of cytochrome b (585 bp) and D-loop (874 bp) from 270 individuals yielded 28 and 128 haplotypes, respectively, resulting in 150 concatenated haplotypes. Mean genetic diversity indices of concatenated sequences were highest in wild Tonle Sap Lake populations (haplotype diversity Hd = 0.994 ± 0.004, nucleotide diversity pi = 0.0077 ± 0.0009), intermediate in wild Cambodian Mekong River populations (Hd = 0.925 ± 0.097, pi = 0.0076 ± 0.0005) and wild Vietnamese Mekong River populations (Hd = 0.832 ± 0.152, pi = 0.0061 ± 0.0018), and lowest in cultured Vietnamese populations (Hd = 0.451 ± 0.198, pi = 0.0021 ± 0.0002). The wild Tonle Sap Lake and cultured Vietnamese populations differed significantly in all genetic diversity indices (P < 0.05). The unique haplotypes and significant genetic divergence (P < 0.01) among striped snakehead populations from each habitat (e.g., lake or floodplain, wild or cultured) suggests habitat-specific genetic structure. Genetic differences among all wild populations were also positively correlated with hydrological distance in the range of 600 km (P < 0.01), suggesting isolation by distance. These findings have important implications for appropriate management of wild and cultured C. striata in Viet Nam and Cambodia. [ABSTRACT FROM AUTHOR]