Physical versus harvest-based measures of capacity: the case of the UnitedKingdom vessel capacity unit system

Effective management of fishing capacity requires reliable estimates of cur rent capacity, and to this end most countries have developed a form of capa city measure usually based on some physical characteristics of the fleet. I n the United Kingdom, the "capacity" measurement system currently in place is used as the basis of existing capacity reduction programmes. Each vessel has a number of Vessel Capacity Units (VCUs) defined by its size and engin e power. An assumption is made that this measure is related to the ability of the fleet to catch fish. More recently, techniques have been developed t o measure capacity directly in terms of potential output. In this paper, th e fishing capacity of a sample of UK otter trawlers and a set of bouts that primarily use static gear (i.e. nets and lines) is estimated using data en velopment analysis (DEA). Estimates are made on a species-by-species basis for the key species harvested. These are compared to the existing measures of physical capacity. The results suggest that VCUs may provide a reasonabl e approximation of fishing capacity for fleets using mobile gear, but may b e inappropriate for fleets using static gear. Implications for capacity man agement based on the physical measures, given the results, are drawn. (C) 2 001 International Council for the Exploration of the Sea.