MEASURING CHANGES IN TECHNICAL EFFICIENCY OVER TIME USING CATCH AND STOCK INFORMATION

Increasing attention has been paid over recent years to the economic p erformance of fisheries. An essential component in the determination o f the economic performance of the industry is the rate of change of te chnical efficiency, a key source of growth of effort that is less obvi ous than changes in nominal measures of effort such as days fished. Th e better we understand how (and by how much) effort changes, the bette r we can determine how to achieve efficient effort reductions, In this paper, a method for estimating changes in technical efficiency over t ime is presented, The method is similar to those used in VPA analysis, but has the advantage that changes in efficiency are estimated direct ly. The method is tested using an artificial data set which has been s ubjected to stochastic variations. The results suggest that the method is able to estimate changes in efficiency with a similar degree of pr ecision. The method is also applied to the western English Channel sol e fishery. The results suggest that there may have been an increase in technical efficiency in the mid-1980s. However, as the data were not fully fishery-independent, the results were ambiguous.