Science & Data

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management.

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management.

This database contains the Stock Assessment Result data from the 2014-2016 research season.

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management and to spur new understanding of the connections between ecosystem components by bringing together the results of many diverse research efforts into one document. However, this year the report has been split into four separate documents, one for the Gulf of Alaska, Aleutian Islands, eastern Bering Sea, and the Arctic1. This new presentation allows for a more cohesive focus on each large marine ecosystem (LME). While this simplifies navigation for the reader, it also better highlights data gaps and research needs within each LME.

Greenland turbot have life history characteristics that complicate assessment surveys in the Eastern Bering Sea and Aleutian Islands region. There continues to be issues in rectifying inconsistencies between the NMFS Shelf surveys and NMFS Slope surveys.

Analyses of new data (namely size and age composition data for 2013 – 2015) made available in September 2015 exacerbated a data conflict with the NMFS EBS Shelf and Slope trawl surveys necessitating unexpected model configuration changes to resolve what are clear structural misspecifications. The EBS shelf survey provides a reasonable index of young fish but as they age, they clearly exit the survey area. The EBS slope survey provides an index of adult fish and typically occurs every other year (except that the 2014 survey was dropped so the most recent data is from 2012). Initial runs of the 2014 Model with the new data (Model 14.0) suggested that recent high recruitment estimates (2007-2010) are closer to average, likely reflecting a change in the availability of these fish to the Shelf survey gear. Re-weighting shelf and slope survey composition data to better account for shifts in distribution relative to survey gear appears to improve model diagnostics while acknowledging that Greenland turbot are distributed to a large degree outside the survey areas and are affected by thermal conditions (shifting further north in warmer years in the EBS).

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management and to spur new understanding of the connections between ecosystem components by bringing together the results of many diverse research efforts into one document.

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management and to spur new understanding of the connections between ecosystem components by bringing together many diverse research efforts into one document. The purpose of the first section, the Report Cards, is to summarize the status of the top indicators selected by teams of ecosystem experts to best represent each ecosystem. Time series of indicators are presented in figures formatted similarly to enable comparisons across indicators. Recent trends in climate and the physical environment, ecosystems, and fishing and fisheries are highlighted in bulleted lists.

Two models are presented for consideration. Model 1 is the model configuration that has been accepted by the SSC for the previous 2 years updated with the most recent data. An error was discovered in the female length at 50% mature used last year and has been corrected in both models presented this year. Model 2 is similar to the models presented for the past 2 years with a parameter for autocorrelation in recruitment. Model 2 differs from last year’s autocorrelated model in that an additional time block (2010-2014) for the longline fishery selectivity was added to improve the residual pattern, and catchability was fixed for shelf and survey indices. The stock continues to be modeled using the same software as previous assessments (Stock Synthesis 3).

The goal of the Ecosystem Considerations report is to provide stronger links between ecosystem research and fishery management and to spur new understanding of the connections between ecosystem components by bringing together many diverse research efforts into one document. There are three main sections: • Executive Summary • Ecosystem Assessment • Ecosystem Status and Management Indicators The purpose of the first section, the Executive Summary, is to provide a consise summary of the status of marine ecosystems in Alaska for stock assessment scientists, fishery managers, and the public. Time series of indicators are presented in figures formatted similarly to enable comparisons across indicators. Recent trends in climate and the physical environment, ecosystems, and fishing and fisheries are highlighted in bulleted lists. The purpose of the second section, the Ecosystem Assessment, is to synthesize historical climate and fishing effects on the eastern Bering Sea/Aleutian Islands and Gulf of Alaska ecosystems using information from the Ecosystem Status and Management Indicators section and stock assessment reports. Notable trends, “hot topics”, that capture unique occurrences, changes in trend direction, or patterns across indicators are highlighted at the beginning. An ongoing goal is to produce ecosystem assessments utilizing a blend of data analysis and modeling to clearly communicate the current status and possible future directions of ecosystems. In future drafts, the Ecosystem Assessment section will also provide an assessment of the possible future effects of climate and fishing on ecosystem structure and function.