Evaluation of fishing power for the purpose of standardizing fishing efforts between fisheries

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For the purpose of reduction in excess fishing capacity, it is indispensable to evaluate fishing power of fishing methods and fisheries. However, fishing power has been evaluated without distinguishing fishing gear selectivity from catching efficiency. This study arranged terminology in terms of fishing power, and presented methods for standardizing catch per unit effort (CPUE) and for estimating fishing gear selectivity and relative fishing intensity including catchability, sampling effort, fishing effort and so on.First, fishing efficiency, catchability and fishing effort were defined clearly. The Tauchi fishing power index that fishing scientists and technologists used to employ for evaluating fishing power can remove effects of temporal and spatial change in resources structure on CPUE, and is hence useful to standardize CPUE, which is similar to standardization by GLM.Second, the SELECT model analysis with fishing effort data can estimate parameters of fishing gear selectivity and catchability at the same time. The split parameter in' the SELECT model was expressed as relative fishing intensity. We successfully modified the SELECT model to analyze the data from paired gear tests with change in sampling effort.Third, the SELECT model was also enlarged for analyzing data in comparative fishing experiments with over-3 fishing gears.Finally, for gillnet as a representative fishing method, effect of mesh size and twine thickness on fishing gear selectivity and catching efficiency was studied. And fishing methods and performance were examined in conger-eel fisheries as an example of multi-fisheries (e.g. longline, trawl, trap-net and tube-pot) and the fisheries management was discussed.