Initial applications of statistical catch-at-age assessment methodology to the Greenland halibut resource

Abstract

In this initial report of the application of SCAA to the assessment of the Greenland halibut resource, a Baseline case with temporally invariant selectivity-at-age vectors is considered together with four variants which allow for serial correlation in survey residuals, temporal variability in commercial selectivity-at-age, and force asymptotically flat commercial selectivity. Only catch- and survey-based data are taken into account, as for the standard NAFO XSA-based assessment. In terms of recent trends, results vary greatly amongst these variants. Two are similar (though slightly above in absolute terms) to the recent negative prognosis indicated by the XSA assessment. Others however (including what reflects the best fit to the data obtained thus far) suggest more optimistic results, in particular indicating increases in abundance over the last decade.