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Distributional changes for fish populations may be difficult to interpret since temperature responses are often confounded with ontogenetic shifts. However, the relative importance of these two types of fish movement (temperature responses and ontogenetic shifts) to population distribution remains largely unstudied. This study presents the first attempt to compare the two types of movement in depth, latitude and longitude for 10 abundant groundfish species across size class and subregion. We utilized large, quality‐controlled datasets from random depth‐stratified, bottom trawl surveys consistently conducted during the summer along NE Pacific shelf from 1996 to 2015. We show that the size structure of each species varied across years and subregions with dramatically strong or poor recruitments for some species in 2015 during a marine heatwave. Principal component analysis (PCA) demonstrated that ontogenetic shifts in depth represented the primary movement pattern while temperature responses in latitude and longitude constituted a major, but a secondary pattern. Re‐run by size class, PCA results further showed that the influence of temperature and ontogeny on population distribution varied by size classes with greater ontogenetic shifts in smaller fish and elevated temperature responses in larger fish. We further show substantial ontogeny‐induced movements by depth, latitude and longitude with high variability among species and subregions. Our analyses suggest that failing to account for size structure can lead to serious misinterpretation of population distributional changes in all three dimensions: depth, latitude and longitude for populations with or without episodic recruitments. [ABSTRACT FROM AUTHOR]

Both the ecological and social dimensions of fisheries are being affected by climate change. As a result, policymakers, managers, scientists and fishing communities are seeking guidance on how to holistically build resilience to climate change. Numerous studies have highlighted key attributes of resilience in fisheries, yet concrete examples that explicitly link these attributes to social‐ecological outcomes are lacking. To better understand climate resilience, we assembled 18 case studies spanning ecological, socio‐economic, governance and geographic contexts. Using a novel framework for evaluating 38 resilience attributes, the case studies were systematically assessed to understand how attributes enable or inhibit resilience to a given climate stressor. We found population abundance, learning capacity, and responsive governance were the most important attributes for conferring resilience, with ecosystem connectivity, place attachment, and accountable governance scoring the strongest across the climate‐resilient fisheries. We used these responses to develop an attribute typology that describes robust sources of resilience, actionable priority attributes and attributes that are case specific or require research. We identified five fishery archetypes to guide stakeholders as they set long‐term goals and prioritize actions to improve resilience. Lastly, we found evidence for two pathways to resilience: (1) building ecological assets and strengthening communities, which we observed in rural and small‐scale fisheries, and (2) building economic assets and improving effective governance, which was demonstrated in urban and wealthy fisheries. Our synthesis presents a novel framework that can be directly applied to identify approaches, pathways and actionable levers for improving climate resilience in fishery systems. [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 [...]

Understanding demographic variation in recruitment and somatic growth is key to improving our understanding of population dynamics and forecasting ability. Although recruitment variability has been extensively studied, somatic growth variation has received less attention, in part because of difficulties in modeling growth from individual size-at-age estimates. Here we develop a Bayesian state-space approach to test for the prevalence of alternative forms of growth rate variability (e.g., annual, cohort-level, or in the first year recruited to the fishery) in size-at-age data. We apply this technique to 29 Pacific groundfish species across the California Current, Gulf of Alaska, and Bering Sea--Aleutian Islands marine ecosystems. About 40% of modeled stocks were estimated to exhibit temporal growth variation. In the majority of stocks, growth trends fluctuated annually across ages in a single year, suggesting that either there are shared environmental features that dictate growth across multiple ages or the presence of some systematic (within-year) observation errors. This method represents a novel way to use size-at-age data from fishery or other sources to test hypotheses about growth dynamics variability. La comprehension des variations demographiques du recrutement et de la croissance somatique est centrale a l'amelioration de la comprehension et de la capacite de prevision de la dynamique des populations. Si la variabilite du recrutement a fait l'objet de nombreuses etudes, celle de la croissance somatique a recu moins d'attention, en raison notamment des difficultes que presente la modelisation de la croissance a partir d'estimations de la taille selon l'age. Nous presentons une approche bayesienne d'espaces d'etat pour evaluer la prevalence de differentes formes de variabilite du taux de croissance (p. ex. annuelle, au niveau de la cohorte ou dans l'annee suivant le recrutement dans la ressource halieutique) dans les donnees de taille selon l'age. Nous avons applique cette technique a 29 especes de poissons de fond du Pacifique des ecosystemes marins du courant de Californie, du golfe d'Alaska et de la mer de Behring--des iles Aleoutiennes. Il est estime qu'environ 40 % des stocks modelises presentent des variations temporelles de la croissance. Dans la majorite des stocks, les tendances de croissance variaient annuellement selon le groupe d'ages dans une annee donnee, ce qui donne a penser qu'il existe des elements partages du milieu qui dictent la croissance selon l'age ou qu'il y a presence d'erreurs d'observation systematiques (durant une meme annee). La methode represente une nouvelle maniere d'utiliser les donnees de taille selon l'age tirees des peches ou d'autres sources pour verifier des hypotheses concernant la variabilite de la dynamique de croissance. [Traduit par la Redaction], Introduction Marine fish productivity varies because of fluctuations in demographic processes such as recruitment, mortality, and somatic growth. Therefore, quantifying causes of variability in these processes and corresponding effects on [...]

Replicate acoustic surveys conducted near Kodiak Island, Alaska, USA, during summers 2001, 2004, and 2006 showed that the short-term effect of commercial fishing activities on walleye pollock (Theragra chalcogramma) during this period was small, in most cases too small to detect. An area with commercial fishing and a nearby comparison area where commercial fishing was prohibited were surveyed before and during the fishery. Acoustic data were used to assess changes in the abundance, geographical and vertical distributions, and small-scale spatial patterns of walleye pollock, which may have occurred after the fishery commenced. A decrease in biomass after fishing began was detected only in 2004. No changes were detected in geographical or vertical distributions that could be attributed to the fishery in any year. Adults did not appear to aggregate or disperse in response to the fishery. Juvenile aggregations did differ between the prefishery and fishery surveys in 1 of the 2 years when juveniles were present. These data suggest that changes in walleye pollock abundance and distribution caused by the fishery are likely quite small compared with natural fluctuations. Des inventaires acoustiques repetes en double realises pres de l'ile de Kodiak, Alaska, E.-U., durant les etes 2001, 2004 et 2006, ont montre que l'effet a court terme des activites de peche commerciale sur la goberge de l'Alaska (Theragra chalcogramma) durant cette periode est faible, dans la plupart des cas sous le seuil de detection. Nous avons inventarie une zone de peche commerciale et une zone avoisinante de comparaison dans laquelle la peche commerciale etait interdite avant et durant la peche. Les donnees acoustiques ont servi a evaluer les changements dans l'abondance, les repartitions geographiques et verticales et les patrons spatiaux a petite echelle qui ont pu se produire chez la goberge apres le debut de la peche. Nous avons decele une reduction de la biomasse apres le debut de la peche seulement en 2004. Aucun changement n' a ete observe dans les repartitions geographiques ou verticales qui aurait pu etre attribue a la peche durant ces trois annees. Les adultes ne semblent pas se rassembler ou se disperser en reaction a la peche. Les rassemblements de jeunes differaient dans les inventaires avant et durant la peche lors de l'une des deux annees pendant laquelle les jeunes etaient presents. Nos donnees laissent croire que les changements causes par la peche dans l' abondance et la repartition de la goberge sont vraisemblablement petits par comparaison aux fluctuations naturelles. [Traduit par la Redaction], Introduction A multiyear study of the interactions between commercial fishing and walleye pollock (Theragra chalcogramma)was conducted near Kodiak Island in the Gulf of Alaska (GOA) in 2000-2006. The goal of [...]

Abstract: In a search for ocean conditions potentially affecting the extent of Pacific hake (Merluccius productus) feeding migrations, we analyzed data collected in 1995 and 1998 by the National Marine [...]

Poleward species range shifts have been predicted to result from climate change, and many observations have confirmed such movement. Poleward shifts may represent a homogeneous shift in distribution, seasonal northward movement of specific populations, or colonization processes at the poleward edge of the distribution. The ecosystem of the Bering Sea has been changing along with the climate, moving from an arctic to a subarctic system. Several fish species have been observed farther north than previously reported and in increasing abundances. We examined one of these fish species, Pacific cod, in the northern Bering Sea (NBS) to assess whether they migrated from another stock in the eastern Bering Sea (EBS), Gulf of Alaska, or Aleutian Islands, or whether they represent a separate population. Genetic analyses using 3,599 single nucleotide polymorphism markers indicated that nonspawning cod collected in August 2017 in the NBS were similar to spawning stocks of cod in the EBS. This result suggests escalating northward movement of the large EBS stock during summer months. Whether the cod observed in the NBS migrate south during winter to spawn or remain in the NBS as a sink population is unknown. [ABSTRACT FROM AUTHOR]

The Alaska Fisheries Science Center of the National Marine Fisheries Service produces stock assessments for major groundfish and shellfish stocks in the Alaskan waters on an annual basis. Stock assessment [...]

Analyses of climate effects often ignore differences in life history for individual species. We analyzed a 34-year time series of eastern Bering Sea fish surveys to evaluate changes in distribution by length and between cold and warm shelf-wide average water temperatures for 20 species over inhabited depth, temperature, and location. All species showed evidence of ontogenetic migration. Differences in distribution between years with warm and years with cold shelf-wide water temperatures varied among species and within species at different lengths. For species where shelf-wide temperature effects were detected, the mid-sized fish were most active in changing spatial distribution. For aquatic organisms ontogenetic migration occurs because life history stages have different environmental requirements. This study illustrates the need to consider species responses to climate change over different life history stages, and that studies on ecosystem responses should take ontogenetic differences into consideration when assessing impacts. [ABSTRACT FROM AUTHOR]

Toxic pollutants such as crude oil have direct negative effects for a wide array of marine life. While mortality from acute exposure to oil is obvious, sub-lethal consequences of exposure to petroleum derivatives for growth and reproduction are less evident and sub-lethal effects in fish populations are obscured by natural environmental variation, fishing, and measurement error. We use fisheries independent surveys in the Gulf of Alaska to examine the consequences of the 1989 Exxon Valdez oil spill (EVOS) for demersal fish. We delineate areas across a range of exposure to EVOS and use spatio-temporal models to quantify the abundance of 53 species-groups over 31 years. We compare multiple community metrics for demersal fish in EVOS and Control areas. We find that areas more exposed to EVOS have more negative trends in total groundfish biomass than non-EVOS areas, and that this change is driven primarily by reductions in the abundance of the apex predator guild. We show no signature of increased variability or increased levels of synchrony within EVOS areas. Our analysis supports mild consequences of EVOS for groundfish communities, but suggests that long time-series and assessments of changes at the community level may reveal sub-lethal effects in marine communities. [ABSTRACT FROM AUTHOR]

The article offers information on the North Pacific Marine Science Organization (PICES) PICES/ICES Section (Strategic Initiative) on Climate Change Impacts on Marine Ecosystems (S-CCME/ SICCME) workshop that was held on November 4, 2016 in San Diego, California. It mentions that the topic was focused on the impact of climate change on fishes and fisheries.