Some further runs of ASPM/SCAA for Gulf of Maine Cod
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University of Cape Town
As suggested in discussions, the ASPM/SCAA assessment approach for Gulf of Maine cod has been rerun commencing in 1964 when the survey time series commence. In addition, the implications of increasing M from the conventional 0.2 to 0.3 are explored. Commencement in 1964 requires the specification of starting conditions, which have been set as θ=0.5 (reflecting the Bsp/K ratio at that time) and ζ=0.4 (the addition to M made to provide a starting age structure). Sensitivities are investigated for the alternatives of Ricker vs Beverton-Holt stock-recruitment relations and of fully estimated vs asymptotically flat selectivity functions (the commercial selectivity functions are fully estimable throughout). In other respects the specifications of the 2007 Reference Case of Butterworth and Rademeyer (2008) have been retained.
Butterworth, D. S., & Rademeyer, R. A. (2008). Some further runs of ASPM/SCAA for Gulf of Maine cod. GARM-III Working paper, 4.