Report of the Study Group on Stock Identity and Management Units of Whiting (SGSIMUW)
reportposted on 2005-01-01, 00:00 authored by ICESICES
This meeting operated predominantly as a priming and coordination meeting to initiate the Study Group on Stock Identity and Management Units of Whiting (SGSIMUW) activities. Consequently, it sought to define the inter-sessional work that is required to address the issue of stock structure and the definition of practical management units. Protocols based on survey data and commercial catch data were presented to illustrate the possible means to evaluate the impacts of population structuring on stock assessments. Some of them, e.g. Gadget, are out-side the resource-base of the Study Group membership, but others that are also based on spa-tially disaggregated datasets (from both survey and commercial data) are likely to provide insight into the issue.Nine working documents were presented at the meeting. Six of these were provided by non-attending contributors and focused on the analysis of various survey series, predominantly the first-quarter International Bottom Trawl Survey (IBTS Q1). The evaluations of the IBTS Q1 indices show the whiting indices to be sensitive to the spatial coverage of the survey and that since 1983, when consistent spatial coverage was first established, a generally coherent set of indices has been produced that is consistent with the corresponding results from catch-at-age analyses. The exception is that for younger ages in particular there are distinct relationships between indices and catch-at-age estimates during two separate periods (1983-1990 and 1991-to date).
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