Index-Removal Estimates of Dredge Efficiency for Sea Scallops on Georges Bank

Abstract

In June of 1999, fishermen were allowed access to the southern section of Georges Bank Closed Area II in the North Atlantic to harvest the large biomass of sea scallops Placopecten magellanicus that had accumulated during a 5-year multispecies fishing ban. Prior to the opening, managers conducted a fine-scale survey of the area and a catch quota was established as a fixed percentage of the estimated biomass. The estimate of biomass was uncertain because it was based on estimates of dredge efficiency that ranged from 16% to 40%. Because survey stations were reoccupied at the end of the fishery and significant removals had occurred, it was possible to use the index-removal method to obtain an estimate of gear efficiency. The estimate was 54% and ranged from 41% to 54% depending on model inputs. The 54% efficiency is believed to represent a maximal efficiency estimate.