ADDENDUM: further SCAA/ASPM assessments of Gulf of Maine Cod including data for 2007 and exploring the impact of age-dependence in natural mortality

Abstract

Deadlines for the submission of the main text of this paper did not allow time for the computation of Frebuild statistics. This statistic is reported here for the one case amongst the 16 assessment options of the main paper for which the estimate of spawning biomass for 2007 was less than B*sp MSY : BevertonHolt D (the “default” case with flat survey selectivity and M = 0.2), together with an explanation of the methodology used for the computation. Further, the main text indicated that rather than considering the mechanisms of domed survey selectivity, a higher age-independent M, or M increasing with age in isolation to account for the relative paucity of older cod in the surveys and fishery, this could be similarly achieved by considering these in combination. To illustrate this possibility, the results for one such combination (assessment Ricker I defined below) are presented here.