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Consideration of economic outcomes is commonplace in most fisheries management systems globally, although only a few jurisdictions have adopted an economic objective as the primary target for fisheries management. Such an objective has been adopted for Australia's federally managed fisheries, with maximum economic yield (MEY) identified as the primary management objective. Correspondingly, target reference points defined in terms of biomass (i.e., [B.sub.MEY]) are used in harvest control rules. In the absence of explicit [B.sub.MEY] estimates, proxy estimates based on maximum sustainable yield (i.e., [B.sub.MSY]) are used. Identifying [B.sub.MEY] in multi-species fisheries is complicated as most stock assessments are undertaken at the individual species level, but economic activity occurs across species. This is further complicated when different fishing activities using different fishing gears and targeting practices (i.e., metiers) are present in a fishery. We employ an age-structured bioeconomic model to estimate [B.sub.MEY] for key species in a multi-species, multi-metier fishery. We find that optimal biomass levels are substantially higher than those assumed under the current proxy-based system, and that the economic targets are sensitive to prices and fishing costs, both of which change over time. Key words: maximum economic yield, MEY, multi-species fisheries, multi-metier fisheries, bioeconomic model, target reference points, 1. Introduction Harvest strategies, also known as management procedures, are increasingly being applied in fisheries management as a means to respond to changes in stock conditions (Holland 2010; Geromont and [...]

Generating accurate data for stock assessments is resource-demanding, necessitating periodic evaluation of survey sampling designs and potential impacts on stock assessments. We developed a framework for bootstrapped resampling of survey age data and calculation of input sample sizes as a function of among-bootstrap variance in age compositions. Data from this bootstrap estimator were then used to evaluate the influence of alternative sampling rates and methods on uncertainty in estimates of the overfishing limit (OFL) calculated using stock assessment models. For dusky rockfish (Sebastes variabilis) and Pacific ocean perch (Sebastes alutus), a 10% decrease in the number of tows sampled upon led to a predicted 5%-6% increase in the CV of OFL (log-log slope = -0.576 to -0.486), which was greater than the 0%-2% increase from a 10% decrease in otolithsper-tow (log-log slope = -0.238 to -0.029). Application of this approach across all stocks monitored in the survey of interest is required to identify which stocks (i) benefit the most from increased sampling of ageing structures or (ii) cost the least in terms of OFL uncertainty owing to reduced sampling. Key words: age composition, data-weighting, stock assessment, sample size, otoliths, Introduction Sustainable fisheries management is contingent upon sound advice informed by the results of stock assessments, which describe the population dynamics of the resource and provide recommendations for future catch [...]

Abstract--The golden king crab (Lithodes aequispinus) has traditionally been managed in the Aleutian Islands by using a constant catch strategy but interest in abundance-based management has emerged with the recent [...]

A management strategy evaluation (MSE) is used to estimate success at achieving conservation goals for marine mammals while also aiming to minimize impacts on commercial fisheries. It is intended to improve understanding of US import rules that require countries exporting fish and fish products to the USA to adhere to marine mammal bycatch standards 'comparable' to those used by the USA. The MSE framework is applied, for illustrative purposes, to export fisheries in Iceland that impact harbor porpoises (Phocoena phocoena), harbor seals (Phoca vitulina), and grey seals (Halichoerus grypus). Several management strategies are evaluated. The harbor porpoise population is estimated to be close to or above its maximum net productivity level (MNPL) and, according to the model, will continue to increase even if current levels of human-caused mortality are unchanged. In contrast, the grey seal and harbor seal populations are below MNPL, and bycatch mortality in the lumpfish (Cyclopterus lumpus) fishery will need to be reduced to allow them to recover to MNPL. Une evaluation des strategies de gestion (ESG) estutilisee pour estimer le succes vers l'atteinte d'objectifs de conservation des mammiferes marins visant aussi a minimiser les impacts sur les peches commerciales. L'objectif est d'ameliorer la comprehension des regles d'importation americaines qui exigent que les pays qui exportent des poissons et des produits du poisson vers les Etats-Unis respectent des normes concernant les prises accessoires de mammiferes marins << comparables >> aux normes utilisees par les EtatsUnis. Le cadre d'ESG est applique, a des fins d'illustration, aux peches vouees a l'exportation en Islande qui ont des impacts sur les marsouins communs (Phocoena phocoena), les phoques communs (Phoca vitulina) et les phoques gris (Halichoerus grypus). Plusieurs strategies de gestion sont evaluees. Il est estime que la population de marsouins communs se situe aux alentours ou au- dessus de son niveau de productivite nette maximum (NPNM) et, selon le modele, qu'elle continuera d'augmenter meme si les taux de mortalite causee par les humains demeurent inchanges. En revanche, les populations de phoques gris et de phoques communs sont sous leurs NPNM, et la mortalite associee aux prises accessoires dans la peche a la grosse poule de mer devra diminuer pour permettre un retour au NPNM. [Traduit par la Redaction], Introduction There is a long history of deliberate exploitation of marine mammals worldwide. Although commercial whaling and sealing have declined mainly due to a combination of regulation and resource depletion, [...]

Many mobile marine taxa are changing their distributions in response to climate change. Such movements pose a challenge to fisheries monitoring and management, particularly in systems where climate‐adaptive and ecosystem‐based management objectives are emphasized. While shifts in species distributions can be discerned from long‐term fisheries‐independent monitoring data, distilling coherent patterns across space and time from such datasets can be challenging, particularly for transboundary stocks. One approach for identifying dominant patterns of spatiotemporal variation that has been widely used in physical atmospheric and oceanographic studies is empirical orthogonal function (EOF) analysis, wherein spatiotemporal variation is separated into time‐series of annual factor loadings and spatial response maps. Here, we apply an extension of EOF analysis that has been modified for compatibility with biological sampling data to a combined US–Russian fisheries‐independent survey dataset that spans the eastern (United States) and western (Russia) Bering Sea shelf to estimate dominant patterns of spatiotemporal variation for 10 groundfish species at a shelf‐wide scale. EOF identified one axis of variability that was coherent with the extent of cold (≤0°C) near‐bottom waters (the cold pool) previously shown to be a key influence on species distributions and ecosystem structure for the Bering Sea. However, the leading axis of variability identified by our EOF analysis was characterized by low frequency changes in the distributions of several species over longer time scales. Our analysis has important implications for predicting variation in species distributions over time and demonstrates a widely applicable method for leveraging combined fisheries‐independent survey datasets to characterize community‐level responses to ecosystem change at basin‐wide scales. [ABSTRACT FROM AUTHOR]

A multispecies fishery management strategy evaluation (MSE) framework based on the example of the groundfish fishery in the Bering Sea and Aleutian Islands region of Alaska was used to examine the interplay between a bycatch species and three groundfish species. The study introduces a framework for a realistic multispecies fishery MSE by accounting for fleet dynamics, multispecies fishery quota allocation, and the temporal dynamics of technical interactions. The quota allocation and the fleet dynamics models were implemented using linear programming, and regression approaches were used to make a realistic projection of future users' behavioral response to changes in the fishery. The models were calibrated and then validated using historical and out-of-sample data, respectively. The results highlight the importance of accounting for technical interactions and their interannual dynamics for both quota allocation and fleet dynamics to design a realistic multispecies fishery MSE (without them, the amount of lost yield increased). Therefore, particular attention should be paid to understanding human behavior as well as its uncertainty and to refining approaches to incorporate this information into a multispecies fishery management strategy analysis. Un cadre devaluation de strategies de gestion (ESG) pour les peches multispecifiques reposant sur l'exemple de la peche aux poissons de fond dans la region de la mer de Behring et des Aleoutiennes de l'Alaska a ete utilise pour examiner l'interaction entre une espece de prise accessoire et trois especes de poissons de fond. L'etude presente un cadre pour une ESG realiste pour les peches multispecifiques qui tient compte de la dynamique de la flotte, de l'attribution des quotas de peche multispecifique et de la dynamique temporelle des interactions techniques. Les modeles d'attribution de quotas et de dynamique de la flotte ont ete mis en application en utilisant la programmation lineaire, et des approches de regression ont ete utilisees pour etablir des projections realistes de la reaction comportementale future des utilisateurs a des changements dans la peche. Les modeles ont ete etalonnes, puis valides en utilisant des donnees historiques et hors echantillon, respectivement. Les resultats soulignent l'importance de tenir compte des interactions techniques et de leur dynamique interannuelle tant pour l'attribution de quotas que la dynamique de la flotte, afin de concevoir une ESG realiste pour une peche multispecifique (sans quoi le rendement perdu augmente). Une attention particuliere doit donc etre accordee a la comprehension du comportement humain, ainsi que l'incertitude associee, et a l'amelioration des approches pour incorporer cette information dans l'analyse des strategies de gestion pour les peches multispecifiques. [Traduit par la Redaction], Introduction Multispecies fisheries are characterized by a complex combination of harvested animals, which vary in productivity and commercial importance. Some species may be productive and commercially valuable, while others are [...]

In the United States, federally managed stocks that fall below a minimum stock size threshold (MSST) are declared overfished and are mandated to be rebuilt to target biomass levels in [...]

Fishery-independent surveys are useful for estimating abundance of fish populations and their spatial distribution. It is necessary in the case of semipelagic species to perform acoustic-trawl (AT) and bottom-trawl (BT) surveys to ensure that sampling encompasses both midwater and demersal components of the population. Abundance estimates from both survey types are negatively biased because of the blind zones associated with fish vertical distribution. These biases can vary spatially and temporally, resulting in confounded trends and additional variation in abundance estimates. To improve abundance estimates for semipelagic species we propose a new method for combining BT and AT survey data using environmental variables to predict the vertical overlap. Using walleye pollock (Gadus chalcogrammus) AT and BT surveys in the eastern Bering Sea as an example, we show that combined estimates provide more reliable whole water column and spatial distribution estimates than either survey can by itself. Although the combined estimates are still relative, they account for the uncertainty in the bias ratio between the two survey methods and the uncertainty associated with the extent of the water column sampled by both surveys. Our method of combining BT and AT data can be extended to other semipelagic species. Les evaluations independantes des peches sont utiles pour l'estimation de l'abondance des populations de poissons et de leur repartition spatiale. Il est necessaire, dans le cas d'especes semi-pelagiques, d'effectuer des releves acoustiques au chalut (AT) et des releves au chalut de fond (BT) pour s'assurer que l'echantillonnage englobe les composantes de profondeur intermediaire et de fond de la population. Les estimations de l'abondance decoulant des deux types de releves ont un biais negatif en raison des angles morts associes a la repartition verticale des poissons. Ces biais peuvent varier dans l'espace et le temps, produisant des tendances confusionnelles et une variation supplementaire dans les estimations de l'abondance. Afin d'ameliorer ces estimations pour les especes semi-pelagiques, nous proposons une nouvelle methode de jumelage des donnees de releves BT et AT faisant appel a des variables environnementales pour predire le chevauchement vertical. Pour un exemple de releves AT et BT du goberge (Gadus chalcogrammus) dans la mer de Behring orientale, nous demontrons que des estimations combinees fournissent des estimations plus fiables pour toute la colonne d'eau et de la repartition spatiale que l'un ou l'autre des deux types de releves utilise individuellement. Bien que les estimations combinees demeurent relatives, elles tiennent compte de l'incertitude du rapport des biais entre les deux methodes de releve et de l'incertitude associee a l'etendue de la colonne d'eau echantillonnee par les deux releves. Notre methode de jumelage de donnees de releves BT et AT peut etre elargie a d'autres especes semi-pelagiques. [Traduit par la Redaction], Introduction Fishery-independent surveys can be useful for estimating the abundance of fish populations and describing their spatial distribution, if the survey results are reliable (both accurate and precise in detecting [...]

Simulation is used to evaluate the ability of a two-region, age-structured assessment model to provide accurate and precise estimates of stock status (i.e., the ratio of female spawning biomass to unfished female spawning biomass) for coral trout (Plectropomus leopardus) on the Great Barrier Reef (GBR), Australia. The model used to generate the simulated data used by the assessment model is a spatially complex age- and sex-structured population dynamics model that captures the protogynous nature of coral trout. Stock status is underestimated (negatively biased), with the extent of negative bias related to misspecification of the breeding strategy of the target fish stock, the impact of the amount of larval connectivity among reefs, the number of reefs closed to fishing, as well as exploitation rates. The estimates of stock status were less negatively biased when fishery-independent index and age- and length-composition data were available from closed areas. The results will inform the development of management strategies for coral trout in the GBR and highlight the importance of basing evaluations of estimation and management performance on operating models that capture ecologically important processes such as metapopulation dynamics and protogynous life history. La simulation est utilisee pour evaluer la capacite d'un modele devaluation structure selon l'age a deux regions de fournir des estimations exactes et precises de l'etat du stock, soit le rapport de la biomasse de femelles fecondes et de la biomasse de femelles fecondes non pechees, pour la loche saumonee, Plectropomus leopardus, dans la Grande Barriere de corail (GBC), en Australie. Le modele utilise pour produire les donnees simulees employees dans le modele devaluation est un modele de dynamique des populations spatialement complexe structure selon l'age et le sexe qui capture le caractere protogyne de la loche saumonee. L'etat du stock est sous-estime (biais negatif), l'ampleur de ce biais negatif etant reliee a la prescription erronee de la strategie de reproduction du stock de poissons cible, a l'incidence de l'ampleur de la connectivite des larves entre recifs, y compris les recifs dans les zones exploitees et fermees, ainsi qu'aux taux d'exploitation. Les estimations de l'etat du stock presentent un biais moins negatif quand des donnees sur un indice independant de la peche et sur la composition age-longueur sont disponibles pour les zones fermees a la peche. Les resultats eclaireront l'elaboration de strategies de gestion pour la loche saumonee dans la GBC et soulignent l'importance de baser les evaluations de la performance de l'estimation et de la gestion sur des modeles operationnels qui capturent les processus importants sur le plan ecologique comme la dynamique de la metapopulation et le cycle de biologique protogyne. [Traduit par la Redaction], Introduction The effectiveness of marine spatial closures as a conservation management tool is well documented (e.g., Lauck et al. 1998; Mangel 2000; Halpern 2003; McCook et al. 2010). Many claims [...]

Simulation is used to explore the effect of spatial heterogeneity and spatial closures on the ability of feedback-control management strategies to achieve goals relating to conservation and utilization of fishery resources. The operating model underlying the projections is based on pink ling, Genypterus blacodes, off southern Australia and assumes that animals are sedentary following settlement. The management strategies are able to move the resource towards the target level in the absence of spatial closures even though assessment results are biased. The probability of reducing the stock below its limit reference point is higher when growth rates vary spatially, but the effect is small. The probability of the stock being above its target reference point is lower when one of the smaller spatial areas is closed. However, performance is markedly different when a larger fraction of the total area is closed, with stock size being substantially larger than the target at the end of the projection period. La simulation est utilisee pour explorer l'effet de l'heterogeneite spatiale et de fermetures de zones a la peche sur la capacite de strategies de gestion commandees par retroaction d'atteindre des objectifs de conservation et d'utilisation des ressources halieutiques. Le modele d'exploitation qui sous-tend les projections repose sur l'abadeche rose, Genypterus blacodes, au large de l'Australie meridionale, et part de l'hypothese que ces animaux sont sedentaires apres leur etablissement. Les strategies de gestion arrivent a amener les ressources vers le niveau cible en l'absence de fermetures, malgre le fait que les resultats devaluation soient biaises. La probabilite de reduire le stock sous son point de reference limite est plus elevee quand les taux de croissance varient dans l'espace, mais cet effet est petit. La probabilite que le stock soit au-dessus de son point de reference cible est plus faible quand une des zones plus petites est fermee. Cependant, la performance est tres differente quand une plus grande fraction de l'aire totale est fermee, la taille du stock etant alors considerablement plus grande que la taille cible a la fin de la periode de projection. [Traduit par la Redaction], Introduction Spatial closures have always been a standard component of the toolbox used to achieve single-species goals in marine fisheries. Closures off the US west coast are used to reduce [...]