A new approach of determining gillnet selectivity based on the relationship between fish length and girth to estimate the length distribution of fish encountering a netA new approach of determining gillnet selectivity based on the relationship between fish length and girth to estimate the length distribution of fish encountering a netAA11547977
A method of estimating the length distribution of fish that encounter a gillnet based on selectivity curve using the length-girth relationship of the target fish was proposed for use in fish surveys. This method was verified in a tank experiment using gillnets for rainbow trout(Oncorhynchus mykiss) of known size composition. Data from on body part of fish caught, near the dorsal fin, were used to estimate the selectivity curve. The curves, expressed as a normal curve, of each mesh size had the same shape, even though each was estimated individually. Additionally, there was a complete linear relationship between the mean of the curves regarded as the optimal girth and the mesh size. The estimated length distribution of the fish population corresponded to the length distribution of fish used in the tank experiment. These results confined the the efficacy of proposed method.