Stock Size Research Articles

Ecosystem-based fisheries management of crab fisheries in the Bering Sea and Aleutian Islands

We review ecosystem-based fisheries management (EBFM) of crab fisheries in the Bering Sea and Aleutian Islands (BSAI) and discuss considerations for future EBFM efforts under a rapidly changing climate. Specifically, we review governance frameworks, ecosystem policy, fishery ecosystem plans, catch accounting systems, trawl bycatch controls, trawl area closures and habitat protections, gear modifications, a Crab Rationalization Program, Ecosystem and Economic Status Reports, and Ecosystem and Socioeconomic Profiles. The strongest EBFM features of this management system include mechanisms to avoid overfishing, use of scientific knowledge, consideration of ecosystem connections, appropriate monitoring, acknowledging uncertainty, stakeholder involvement, and decisions that reflect societal choice. Some EBFM principles, such as the efficacy of gear and area closures and accounting for the dynamic nature of ecosystems have room for improvement. In spite of the large number of EBFM measures in place, three of the eight BSAI crab stocks with biomass estimates were below their minimum stock size thresholds, and thus classified as “overfished” in 2023. The lack of apparent correspondence between implemented EBFM actions and crab stock trends may indicate that environmentally driven sporadic recruitment, spikes in natural mortality, and stock range shifts mute favorable responses to EBFM actions or that outstanding critical EBFM measures have yet to be addressed. In the face of recent large-scale changes in the marine ecosystems of the BSAI and an outlook for greater changes in the future, it is increasingly important to routinely reevaluate interactions between crab, their ecosystems, fisheries and fishing communities.

Disposing of Unwanted Firearms and Firearm Injury Prevention

This comparative effectiveness study estimates the size of the US firearm stock by 2034.

Phenotypic and Molecular Characterization of Staphylococcus aureus in Dairy Farms from Henan Province and the Inner Mongolia Autonomous Region, China.

Staphylococcus aureus, a prevalent pathogen associated with infectious and foodborne diseases, is also a significant cause of intramammary infections in dairy farms. This study aimed to determine the phenotypic and molecular characterization of S. aureus in two different stock sizes of dairy farms in Henan province (HN) and the Inner Mongolia autonomous region (IM), China, through biofilm formation, antimicrobial resistance, virulence, and molecular type of S. aureus isolates. In HN, 74 S. aureus isolates (60.7%) were recovered from 122 bulk tank milk samples, while in IM, 24 S. aureus isolates (17.4%) were detected from 161 samples soured from various origins. Notably, 25.7% (19/74) of isolates in HN and 20.8% (5/24) in IM exhibited multidrug-resistant (MDR) phenotypes. Molecular typing revealed distinct patterns: ST97 (n = 32) and spa type t189 (n = 20) predominated in HN, whereas ST50 (n = 13) and spa type t518 (n = 11) were prevalent in IM. Additionally, three isolates harbored both tsst-1 and lukF-PV genes, and two MRSA strains displayed a MDR phenotype in raw milk samples from HN. Biofilm formation was observed in 91.8% strains. Phylogenetic analysis identified two subpopulations (lineages 1 and 2). Among them, cluster 6 in lineage 2 comprised S. aureus strains from three sources within a farm, suggesting potential cross contamination during different stages in IM. Remarkably, among 19 MDR isolates in HN, ST398 MSSA strains exhibited a higher multidrug resistance compared to non-ST398 MSSA strains. This study underscores the high prevalence and diverse characteristics of S. aureus in raw milk, necessitating enhanced surveillance and control measures to mitigate associated risk.

The role of larval transport on recruitment dynamics of red mullet (Mullus barbatus) in the Central Mediterranean Sea

Recruitment success depends on external forcing mechanisms such as ocean currents that affect the transport of eggs and larvae to favorable habitats. In this study, we investigated the role of larval transport in the recruitment of Mullus barbatus in the Central Mediterranean Sea by modeling the recruits' abundance as a function of both spawning stock size and dispersal rates of the species’ early life stages. Our analysis involved twenty years of data on recruits and spawners abundance obtained from scientific trawl surveys, and data on larval dispersal rates derived from a combination of actualized published sources and original data. By calculating the estimates of retention, import and uniformity of the contribution of the spawning areas distributed among different Geographical Sub Areas (GSAs) in the Sicilian nurseries, we assessed their contribution to recruitment using modified Ricker stock size-recruits models. In particular, our results show that a high uniform contribution from spawning areas within GSA16, mainly related to the oceanographic patterns promoting larval retention, together with spawners abundance, significantly reduced the variability of red mullet recruitment. We further highlighted that when switching from a higher to a lower level of evenness of contribution to the recruit population from different spawning areas in the GSA16, the expected spawning stock abundance per recruit for a given fishing pattern can suffer a rapid short-term decline, which is likely to have negative consequences for stock assessment and management decisions. Our results suggest that larval transport plays a crucial role in explaining the interannual variability of recruitment, thereby contributing to a better understanding of stock size variation. Additionally, our study enhances the understanding of the spatial dynamics involved in the recruitment of this species, which is of increasing interest within fisheries management frameworks.

Occurrence and Strength of Instantaneous and Intracohort Density-Dependence in Northeast Atlantic Fish Stocks.

Biological reference points (BRPs) used in fisheries management do not include density-dependent (DD) growth, with DD processes only considered in the stock recruitment relationship. Not accounting for DD on somatic growth has led to criticism that such BRPs underestimate the compensatory effects of DD at low stock size, and therefore risk foregone catch opportunities. Here, we analyse 81 stocks from the Northeast Atlantic for evidence of DD growth, defined as the process in which stock size affects somatic weight. We evaluate the following questions: (1) How many stocks have experienced instantaneous DD growth and do stocks of the same species display similar trends? (2) Is there a common instantaneous DD growth relationship shared by all stocks? (3) For stocks exhibiting significant instantaneous DD growth, can we quantify the strength of the relationship? (4) Is DD growth operating as an intra-cohort process as opposed to an instantaneous effect? Results reveal that only the weight of recruits exhibits a common instantaneous DD growth while the other responses analysed show a positive, noncompensatory effect, suggesting that other processes are at work. All responses examined showed significant temporal autocorrelation, which, when not accounted for, suggest apparent instantaneous DD growth in several stocks. Comparison of instantaneous against intracohort DD growth showed an increase in the number of stocks with significant DD growth, although, as for instantaneous DD growth, this declined greatly when temporal autocorrelation was accounted for. Our results counteract the a priori assumption that DD growth compensation is related only to stock biomass or density, suggesting that DD growth should be dealt case-by-case. Consequently, management practices that aim to fish down stock biomass with the anticipation of triggering DD growth will be associated with greater asymmetric risks than keeping biomass at levels where replacement yield does not rely on it.

Multi-marker DNA metabarcoding for precise species identification in ichthyoplankton samples

Ichthyoplankton monitoring is crucial for stock assessments, offering insights into spawning grounds, stock size, seasons, recruitment, and changes in regional ichthyofauna. This study evaluates the efficiency of multi-marker DNA metabarcoding using mitochondrial cytochrome c oxidase subunit I (COI), 12S rRNA and 16S rRNA gene markers, in comparison to morphology-based methods for fish species identification in ichthyoplankton samples. Two transects with four coastal distance categories were sampled along the southern coast of Portugal, being each sample divided for molecular and morphological analyses. A total of 76 fish species were identified by both approaches, with DNA metabarcoding overperforming morphology—75 versus 11 species-level identifications. Linking species-level DNA identifications with higher taxonomic morphological identifications resolved several uncertainties associated with traditional methods. Multi-marker DNA metabarcoding improved fish species detection by 20–36% compared to using a single marker/amplicon, and identified 38 species in common, reinforcing the validity of our results. PERMANOVA analysis revealed significant differences in species communities based on the primer set employed, transect location, and distance from the coast. Our findings underscore the potential of DNA metabarcoding to assess ichthyoplankton diversity and suggest that its integration into routine surveys could enhance the accuracy and comprehensiveness of fish stock assessments.

Incorporating Honey Badger Algorithm in Estimating Gamma Distribution With Application to Stock Price Modelling

This study evaluates the performance of various estimation methods in stock price analysis across diverse parameters, focusing on the Honey Badger Algorithm (HBA). The purpose is to determine the most accurate and reliable method for parameter estimation. Methodologically, we analyze data spanning eight years from publicly traded Malaysian property companies, employing financial metrics such as Mean Absolute Error (MAE) and Root Mean Square Error (RMSE). Our findings highlight HBA’s consistent precision in parameter estimation, with values closely aligning with initial parameters across different stock sizes. For example, HBA-Gamma model achieves an MAE of 0.0592 and an RMSE of 0.8458 for 13 stocks, demonstrating its proficiency in capturing stock price distributions in dynamic markets. In contrast, the Artificial Immune System (AIS) provides reasonable estimates but with higher variability. The Regression Method exhibits mixed outcomes, displaying accuracy in some cases but notable variability and reduced precision, especially with larger datasets. The Moment Method, while adequate, shows slightly higher variance compared to both HBA and AIS. Further analysis using Log Likelihood values confirms HBA’s superior fit to the data, consistently surpassing AIS, Regression Method, and Moment Method in likelihood maximization across various stock numbers. Specifically, HBA exhibits lower MAE and RMSE values of 0.1034 and 0.06723, respectively, for 26 stocks, further validating its effectiveness in parameter estimation and stock price prediction. These findings underscore the importance of integrated approaches that account for market nuances rather than relying solely on individual model forecasts. The results affirm HBA’s potential for informed investment decision-making, emphasizing its robust performance and enhanced predictive capabilities compared to alternative methodologies. However, further research is needed to assess the generalizability of these findings to other markets and contexts.

Методи обґрунтування запасів запасних частин у системі управління транспортним процесом

The article formulates directions and analyzes the possibilities of substantiating and choosing the most optimal variant of applying mathematical models for forecasting the number and range of spare parts. The provided recommendations allow to take into account the multi-brand fleets of motor transport enterprises and trends for extrapolation in the short term, identified by the results of observations in real operating conditions. The main reasons for the occurrence of prolonged vehicle downtime due to technical malfunctions are considered. Traditional methods of planning spare parts inventories based on the use of reliability theory and results of mileage forecasting, standard time to failure; inventory management theory and statistical methods for forecasting random processes; methods of operations research; economic and mathematical methods; stochastic methods of transformation of random variables are analyzed. The article formalizes the grouping of factors that affect the size of stocks and the range of spare parts in the operation of rolling stock of enterprises, depending on the state of the system of organization of work of services for maintenance and repair of vehicles; structure of the fleet and technical characteristics of vehicles; level of development of the production base; availability, interest and qualification of personnel; operating conditions of automotive equipment. It is proposed to improve the logistics of spare parts inventory management and to formulate measures to improve the performance of carriers based on an assessment of the total costs incurred by the enterprise to maintain the reliability of rolling stock in operation and taking into account the amount of lost profit due to vehicle downtime in the technical service units. At the same time, it is recommended to use the mathematical apparatus of fuzzy set theory for decision-making, which allows formalizing the parameters of vaguely defined expectations of consumers of motor transport services and reducing the subjectivity of decision-making when solving problems of optimizing spare parts stocks in the transport process management system based on the analysis of the structure of consumer properties and service quality indicators.

Determinants of Market Outlet Choice for Smallholder Broiler Farmers in Leribe District of Lesotho

Smallholder broiler farmers struggle to access lucrative formal markets because of low economies of scale, high transaction costs, a lack of awareness of market demand, poor production practices that are not oriented towards meeting the quality and quantity required in the market, poor infrastructure that raises transaction costs, and post-harvest losses. Therefore, this study examined the socio-economic, market and institutional factors that influence broiler farmers’ choice of market outlets in Leribe. The study adopted a random utility maximization theory and transaction cost theory to explain the farmers’ decision process regarding the choice of marketing outlet available in the study area. A total of 114 respondents for this study were selected from five villages using a two-stage sampling technique. The survey data was collected through a structured questionnaire. The MVP model results revealed that gender, vehicle ownership, stock size, contract agreement and access to extension services significantly influenced the choice of market outlets. Therefore, this study recommends the government and development partners consider interventions that will increase broiler production such as enhancing credit access, promoting contract farming, group membership and providing institutional support. The study also recommends policies that will facilitate the adoption of Good Agricultural Practices (GAP) to improve farmers’ access to the lucrative formal market outlets available in the study area. The Government of Lesotho should adopt policies that aim at linking smallholder farmers to formal markets, encouraging contract farming and facilitating the adoption of a Market Information System (MIS) to harmonize the flow of market information among exchange partners in broiler marketing.

David Henry Cushing. 14 March 1920 — 14 March 2008

David Cushing was Britain's foremost twentieth-century marine fisheries ecologist, who did more than anyone else to develop the subject into a distinctive science over a career of more than 50 years. He was born and raised in Northumberland, and took both his first degree and a DPhil at Oxford, separated by war service in the Royal Artillery. He married Diana Antona-Traversi in 1943, and they had one daughter, Camilla. He worked for the whole of his career at the Fisheries Laboratory, Lowestoft, where he started in 1946 as a scientific officer, studying plankton off the northeast coast of England, and eventually becoming deputy director and head of the Fish Population Dynamics Divi­sion until his retirement in 1980. He published around 200 papers and reports, and wrote 11 books on marine ecology and fisheries, with four principal areas of interest: fisheries acoustics; planktonic biological production in the sea; the causes of the collapse of the North Sea herring; and the factors controlling recruitment of young fish, notably the influences of stock size and of climate. He famously proposed the match/mismatch hypothesis to explain how the great variability of fish recruitment arises from minor variations in climate from year to year. He died on 14 March 2008, on his eighty-eighth birthday.

Analysis of Poultry Farmers’ Utilization of Agricultural Credit in Jos South Local Government Area of Plateau State, Nigeria

This study analyzed poultry farmers’ utilization of agricultural credit in Jos South Local Government Area of Plateau State, Nigeria. The population for the study consists of all the registered poultry farmers in Jos South Local Government Area. Multistage sampling technique was used in selecting the respondents for the study. Primary data were collected through the use of questionnaires and interview schedule and were subjected to both descriptive and inferential statistics. Findings from the study showed that majority (86%) of the poultry farmers’ were men, with a mean age of 42 years. Majorities (89%) were married and had five people on average per home. The study also showed that 51% of the farmers were educated beyond high school with a mean farming experience of 9 years and average stock size of 1658 birds. The responders received an average credit amount of ₦357224 while the average amount utilized for poultry business was ₦290164. About 75% of the farmers utilized the loan given to expand their existing farm business. Gender, household size, farming experience and flock size were the significant determinants of agricultural credit utilization by the poultry farmers. Inadequacy of the credit amount received (58.0) and competing family needs (32%) were the main obstacles to using agricultural credit among the poultry farmers. The study recommended more budgetary allocations and farmer’s friendly policies by financial institutions to enable bigger volumes of disbursements to farmers.

INFORMATION NEEDS ANALYSIS OF POULTRY FARMERS IN ABIA STATE, NIGERIA

Poultry production will fail to attain its peak and improve food security if the information needs of the farmers are not met. This study analysed the information needs of poultry farmers in Abia state, Nigeria. Multistage sampling procedure was employed in selecting 117 respondents. Data on respondents’ socioeconomic characteristics, information needs, information sources and information utilization were collected using structured questionnaire and analysed using percentages, mean scores and ordinary least square. Results revealed 59.8% of the poultry farmers were male with mean age of 34years while, 94.0% had above primary level of education. Average stock size was 105 birds and average monthly income was N128,500.00. The farmers needed information on disease identification (87.2%), drugs and vaccine use (82.9%), veterinary services (79.5%), feed formulation (75.2%) and modern agricultural equipment (74.4%) among others. Most of the farmers sourced information from friends and relatives (94.9%), televisions (78.6%), the internet (73.5%), radios (72.6%), veterinary services (68.4%) and extension agents (60.7%). Furthermore, the farmers effectively utilised all information received, except that on modern day agricultural equipment (x̄ = 1.99). Farmers’ socioeconomic characteristics were significantly related to level of information utilization at 5% α-level. To succeed in the business and contribute to food security, poultry farmers need lots of information. It is therefore recommended that information service providers should source adequate, timely, appropriate, and authentic information from reliable sources like research institutes and communicate same to the farmers for their use. Modern day agricultural equipment should be provided at subsidized rates and the farmers taught how to use them to boost production.

Soil Carbon and Nitrogen Stocks and Their Influencing Factors in Different-Aged Stands of Sand-Fixing Caragana korshinskii in the Mu Us Desert of Northwest China

Establishing artificial sand-fixing shrubs is a key measure to curb dune flow and drive changes in the soil stocks and cycling of carbon and nitrogen. But our understanding of these dynamics across years of sand-fixing afforestation and the factors influencing them remains inadequate, making it hard to accurately assess its capacity to sequester carbon. To fill that knowledge gap, this study investigated soil organic carbon (SOC) and soil total nitrogen (STN) stocks in Mu Us Desert under artificial sand-fixing shrub stands of different ages (10, 30, 50, and 70 years old) vis-à-vis a mobile sand dune, to determine whether Caragana korshinskii afforestation improved stock characteristics and whether SOC and STN stocks were correlated during the restoration processes. The results showed that the pattern observed is consistent with an increase over time in the stocks of both SOC and STN. At 10, 30, 50, and 70 years, these stocks were found to be 1.8, 2.3, 3.2, and 5.5 times higher for SOC, and 1.3, 1.6, 2.1, and 2.7 times higher for STN, respectively, than those of the control (mobile sand) dune. Stocks of SOC and STN mainly increased significantly in the 0–10 cm soil layer. The SOC stock was correlated positively with the STN stock as well as the C:N ratio. The slope of the regression for the C:N ratio against stand age was positive, increasing slightly faster with afforestation age. Additionally, our findings suggest that during the establishment of artificial stands of shrubs, the size of the STN stock did not expand as fast as the SOC stock, resulting in an asynchronous N supply and demand that likely limits the accumulation of soil organic matter. This research provides important evidence for the sustainable development of desertified ecosystems.

Total Carbon Storage in Uneven-Aged Pure Beech Stands in the Western Part of the Balkans

Forest ecosystems represent one of the largest and most important ecosystems on Earth, containing close to 80% of the biomass of our planet. As such, they play a significant role in the global carbon cycle because through photosynthesis, forests absorb more carbon than they emit and thus accumulate it. The most important species in deciduous forests in Europe, European beech (Fagus sylvatica L.), is of exceptional importance from the aspect of carbon storage. Considering that the state of carbon in pure beech forests is poorly investigated in the western part of the Balkans, the need for total carbon research was imposed to complete the picture of its stocks and factors that impact it. Research on total carbon (TC) storage in uneven-aged pure beech stands in the western part of the Balkans was carried out in three regions located approximately at the same latitude, but different longitude, imposing different macro-habitat characteristics. This research aimed to determine the TC stock and to examine the effects of orographic factors, stand canopy, and macroclimate on its values. TC stock in forest biomass was determined using appropriate regression equations and formulas, while soil organic carbon stock was determined using ICP forests methodology. Effects of different factors on carbon stock were examined using ANOVA (Type II Sums of Squares), General Linear Hypothesis Test (GLHT), and regression analyses. It was found that the largest TC stock is located in the region of Eastern Serbia (SRB) where its macroclimate is classified as suitable for hornbeam and sessile oak or mixed beech-oak stands. It was found that anthropogenic activity plays a significant role in the size of the carbon stock stored in above-ground biomass via alteration of forest canopy. The results also indicate that Aboveground Carbon (AGC) stocks are approximately proportional to Belowground Carbon (BGC; C in belowground biomass + soil C) stocks. What makes the difference is the structure of BGC, as the share of Soil Organic Carbon (SOC) is higher in the regions of Eastern Republic of Srpska (ERS) and Western Republic of Srpska (WRS), which are climatically classified as highly suitable for beech. Further analysis has shown that the amount of SOC decreases with increasing aridity levels. Given the results, management goals should be aimed at increasing the stock of biomass for the sake of carbon sequestration and for reducing the adverse effects of climate change, as a large amount of carbon can be stored in the above-ground and belowground biomass.

Models for optimising the volume of material flows in the technological chain of corporate vertically integrated structures of the agricultural sector

The relevance of this study lies in the need to optimise supply cycles and volumes in value chains, which helps to reduce costs and increase the profitability of agricultural enterprises. The purpose of this study was to investigate and optimise the costs of initial material flows in the production subsystems of corporate vertically integrated structures of the agricultural complex under conditions of non-stationary demand. To fulfil this purpose, the study investigated the relationship between the amount of raw material stock stored in the production subsystem and the time of its consumption, based on which an extended model of the economic order quantity (EOQ) was considered, which, apart from the defined costs, also considers the costs of raw material shortages associated with the inability to fulfil deliveries and losses associated with supply failures caused by the unpredictability (stochasticity) of the order flow itself. It was found that in continuous production systems there is an opportunity to reduce the costs associated with failures by using an additional regular supply batch. For this, the mathematical “point-of-order” model was built based on the theory of mass service, which allows determining not only the best point to order, but also the optimal amount of the safety stock. A model for optimising the volume of material flows was proposed, which combines the model of the economic order quantity order adapted for use in product subsystems of corporate integrated structures of the agricultural complex and the “point-of-order” model, which allows calculating the minimum size of the insurance stock of raw materials using the tools of operations research. As an example, the material flow was optimised for Kivshovata Agro LLC. The findings of the study, such as the use of analytical tools and models for determining the economic order quantity and safety stock, can be used by the management of agricultural enterprises to improve the efficiency of material flow management

Risks of regionalized stock assessments for widely distributed species like the panmictic European eel

Abstract In fisheries management, accurate stock assessment is pivotal to determine sustainable harvest levels or the scope of conservation measures. When assessment is decentralized and methods differ regionally, adopted approaches must be subjected to rigorous quality-checking, as biased assessments may mislead management decisions. To enable recovery of the critically endangered European eel, EU countries must fulfill a biomass target of potential spawner (“silver eel”) escapement, while local eel stock assessment approaches vary widely. We summarize local approaches and results of ground-truthing studies based on direct silver eel monitoring, to evaluate the accuracy of eel stock assessments in retrospect and identify bias sources. A substantial fraction of eel habitat is currently unassessed or assessed by unvalidated approaches. Across assessment models for which validation exists, demographic models frequently overestimated actual escapement, while misestimations of extrapolation (“spatial”) models were more balanced, slightly underestimating escapement. Stock size overestimation may lead to overexploitation or insufficient conservation measures, increasing the risk of stock collapse or slow recovery in coordinated frameworks. Underestimations may imply inefficient allocation of conservation efforts or negatively affect socioeconomy. Our work highlights the risks of regionalizing assessment responsibilities along with management decisions, calling for a common assessment toolbox and centralized quality-checking routines for eel.

Leveraging digital footprints data for accurate estimation of the residential housing stock in the United Kingdom, 1997–2022

ABSTRACT This paper explores the use of digital footprints data to improve on the limited information available on the size and distribution of the residential housing stock in the United Kingdom over the past two decades. We use a subset of a large dataset consisting of the names and addresses of more than one billion individuals dating back to 1997 (LCRs: Linked Consumer Registers) to calibrate property lifecycle information within an authoritative geolocated address and property dataset. We validate the results of our novel calibration method against official estimates by the UK government covering the same period. We further show that our calibration method, based on individual level data, captures a much larger share of the residential housing stock since 1997 than would have been possible with other available data sources. We argue that these housing stock estimates are fundamental to the development of a comprehensive digital footprints data infrastructure that has the potential to significantly enhance population, migration, and other social statistics in the UK. More generally, this study highlights the benefits of using digital footprints data in refining, calibrating, and extending existing datasets.

Stock Size and Stock Density

Stock Size and Stock Density

Catch uncertainty and recreational fishing attraction: Propositions and future research directions

AbstractWhy do people fish for recreation? Social science literature suggests that both catch (e.g., number or sizes of fish) and non‐catch dimensions (e.g., nature experience, temporary escape) play a role. After reviewing the literature from environmental psychology, neuroscience, anthropology, recreational fisher motivation research as well as popular fishing books, I find that the opposite of catching fish, more specifically the uncertainty of the catch, maybe another, perhaps fundamental force that explains the attraction of the activity to millions of people. There appears to be strong utility in the gaming nature of the activity. This quality may contribute to explain various patterns that are well known, e.g., the overinvestment of time and money by recreational fishers that drastically exceed the market value of fish, the lack of self‐regulation of a local recreational fishery in terms of effort being spent also on low stock sizes, the disutility associated with providing certain catch probability information, diminishing marginal utility return for increasing catch rates, management regulations that make fishing harder than necessary, suboptimal satisfaction despite rising catch rates, and finally the dominance of men among populations of recreational fishers. I present a serious of testable propositions and call for a novel research focus that seeks to better understand what makes catch ambiguity attractive psychologically and emotionally.

Deep genetic divergence among bluefish (Pomatomus saltatrix) of the Southwestern Atlantic

AbstractNeglected cryptic diversity can lead to the permanent loss of locally adapted alleles, which can reduce resilience to rapid environmental change. It can also result in overestimation of fisheries stock sizes that can result from treating different species as if they belonged to one. Bluefish (Pomatomus saltatrix) is considered a circumtropical and subtropical species and an important fishery resource all over the world. Differences in ecologically relevant traits are observed among isolated populations. Also, in the Southwestern Atlantic, molecular data suggest multiple populations, but these are treated as a single fish stock by regulatory agencies due to a lack of definitive information. We used whole mitogenome sequences, nuclear (rho) and mitochondrial (coxI and cytb) genes, as well as microsatellites to investigate historical and current genetic population structure and parameters of bluefish in the Western Atlantic. A total of 263 samples were collected along the Brazilian coast and in the USA (New Jersey, Northwest Atlantic). Data revealed the existence of two evolutionarily significant units (ESU) of bluefish along the South American coast, later confirmed by whole mitogenome sequencing of both haplogroups. These two ESUs have a mostly parapatric distribution, with some areas of overlap, which vary along the year. We also conducted seasonal sampling in Brazil to investigate migration patterns. ESUs occur mostly north and south of parallel 23° 40′ S, with an overlap area that varied seasonally. The level of differentiation between those two ESUs in the SW Atlantic, even in sympatry, is as high as that found between them and those from the NW Atlantic and Europe. Parapatric distribution and restricted gene flow suggest the existence of ecological barriers and local adaptation. The splitting of an ancient population from the Southwestern Atlantic into two putative species is important to understand bluefish evolutionary diversification and has implications for fishery regulatory measures in Brazil.