A bioeconomic analysis of the Norwegian spring spawning herring (Nssh) stock

A biological model, belonging to the Beverton and Holt age-structured family, for the Norwegian spring spawning herring (NSSH) is simulated, the outcome of which compares well with actual data on the fishery. This model is then combined with an economic model to help investigate how optimal a management policy of constant fishing mortality will be for a fishery such as the NSSH, which has a highly fluctuating stock biomass. For the range of constant values of fishing mortality explored, and a time horizon of the simulation of 20 years, a constant fishing mortality of 0.15 turns out to be economically optimal. It should be noted that this result is sensitive to variations in the assumptions underlaying key variables of the fishery. For example, when a constant rather than a variable recruitment was assumed a different optimal fishing mortality rate was obtained