IMPROVED INDEXES OF CATCH RATE IN THE FISHERY FOR BLACKLIP ABALONE, HALIOTIS-RUBRA, IN NEW-SOUTH-WALES, AUSTRALIA

There was a non-linear relationship between daily catch and effort wit hin the NSW abalone fishery between 1983 and 1995. Larger catches were collected at a faster rate than small catches. To account for this, a generalized linear model was fitted which described the observed effo rt as a function of catch and several other standardizing variables. T his model provided indices of catch rate that were significantly diffe rent from those derived from a more traditional analysis of CPUE which does not account for the non-linear relationship between catch and ef fort. Changes in indices of catch rate from the analysis of catch and effort were associated with major management changes, including increa ses in the minimum length limit and the introduction of individual quo tas. Increases in catch rate between 1992 and 1995 were not associated with changes in management, and suggest that densities and abundance of abalone on the NSW coast may have increased. This interpretation is strengthened when catch rates are considered in conjunction with inde pendent surveys of abundance. Calculation of standardized indices of c atch rate that acknowledge the non-linear relationship between catch a nd effort, and their interpretation in conjunction with other informat ion, is likely to improve the potential of catch rate as an indicator of change within the NSW abalone fishery. (C) 1998 Elsevier Science B. V. All rights reserved.