Research Document - 2011/136
Moving towards the sustainable fisheries framework for Pacific herring: data, models, and alternative assumptions; Stock Assessment and Management Advice for the British Columbia Pacific Herring Stocks: 2011 Assessment and 2012 Forecasts
By S.J.D. Martell, J.F Schweigert, V. Haist, and J.S. Cleary
B.C. herring stocks are managed as five major and two minor stock areas. Accordingly, catch and survey information is collected independently for each of these seven areas and science advice is provided on the same scale. All available biological data on spawn deposition, size and age composition of the spawning stocks, as well as commercial harvest data, were used to determine current abundance levels. In recent years external reviewers have suggested substantial revisions to the herring assessment framework, including revisions to the catch-age model. As such, we present a new integrated statistical catch-age model ( ISCAM ) for jointly estimating the abundance of Pacific herring stocks and associated reference points (Part I). This includes simulation testing to demonstrate the model is capable of estimating all parameters and parameterization of the new assessment model as per the previous assessment model (Herring Catch Age Model, or HCAM) in order to compare parameter estimates and estimates of spawning stock biomass (using data from 1951:2010) between old (HCAM) and new (ISCAM ) models. Part II of this document implements this new assessment framework using the data for the five major and two minor stock areas. Finally, we present pre-fishery biomass estimates and catch advice based on decision tables that utilize poor, average, and good age-3 recruitment forecasts as well as risk probability tables to inform decision making.
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