Sensitivity analysis of the multispecies virtual population analysis model parameterized for a system of trophically-linked species from the eastern Bering Sea

Abstract

A sensitivity analysis of a multispecies virtual population analysis (MSVPA) model parameterized for the Bering Sea was carried out using two methods for the analysis. In the first method, four variables related to the predation mortality M2 and population size of age-1 walleye pollock (Theragra chalcogramma) and Pacific cod (Gadus macrocephalus) were chosen as response variables. Results suggested that the response variables of walleye pollock were sensitive to the residual mortality M1 of walleye pollock, the stock size of arrowtooth flounder (Atheresthes stomias) and ration of both predator species. Pacific cod response variables were sensitive only to variables related to Pacific cod. These results reinforce the importance of cannibalism in the dynamics of walleye pollock and Pacific cod. Results from the individual perturbation parameter analysis showed that the changes produced by large positive perturbations in the "other food" parameter were small. The overall results suggest that the MSVPA model can be considered robust. These results help to recognize the potential use of MSVPA as a tool to assist in broadening the management of the fishery resources from the Bering Sea within a multispecies perspective.