Spatial Model for an Exploited Shellfish Population, and its Application to the Georges Bank Scallop Fishery

Existing fisheries models employ the "unit stock" concept that makes no explicit allowance for spatial distribution of biomass and effort over a fishing ground. The utility of the unit stock concept rests largely upon the "dynamic pool" assumption. However, this is both invalid for sedentary species, and difficult to apply when information on spatial distribution by statistical subunits is available, as for the Georges Bank (lat. 42°N, long. 67°W) scallop population. By reference to the Georges Bank scallop fishery, more realistic general assumptions for a spatial model of shellfish populations are:a) Recruitment occurs in patches of random size and location with the constraint that local biomass does not exceed the virgin biomass of each unit area.b) The fraction of effort expended within each statistical area of a fishing ground is either determined by available local biomass alone (proportional effort allocation) or in combination with "traditional fishing practice."Therefore, a spatial model (YRAREA) ...