Results for an illustrative empirical decisison rule for hake projections for C3 scenarios in the context of alternative options for initial TAC reduction levels

Rademeyer, Rebecca A; Plagányi, Éva E; Butterworth, Doug S

Results for an illustrative empirical decisison rule for hake projections for C3 scenarios in the context of alternative options for initial TAC reduction levels

Working Paper

2005

Publisher

University of Cape Town

Department

Marine Resource Assessment and Management Group

Faculty

Faculty of Science

Abstract

This paper reports further investigations of the performance of an illustrative EMPIRICAL decision rule (OMP) for the hake resource for C3 scenarios only because these reflect (on average) a current spawning biomass ratio for M. capensis compared to M. paradoxus of about 2:1, which is considered more plausible than the much higher corresponding ratios for the C1 and C2 scenarios. Initial annual reductions of 5000, 8000 and 10000 tons are considered for the first two years. After that initial period, TAC changes are restricted to a maximum of 5%, both up and down. Results for the C6 scenarios (C6 corresponds to C3 in the same way as C4 to C1 – reflecting a greater proportion of M. capensis in past offshore trawl catches) show a reduction of about 15000t in the annual TAC for similar final depletion statistics (the lower 5%ile being of primary importance as risk is the concern here) for M. paradoxus.