Abstract
Offshore trawlers, belonging to Chõshi Fisheries Cooperation, changed their fishing gear and fishing method from Danish seine and Japanese type otter trawl to stern trawl for the years of 1971-1978.
The authors compared the relative fishing ability by type of vessel according to fishing method and tonnage class for the above-mentioned period, with the coefficient of fishing ability which was obtained from catch per draught of each type of vessel by the method of least squares, using the data of the fisheries statistics.
The fishing ability of stern trawl is generally much better than that of Japanese type otter trawl in most years when they were operated together, and that of Danish seine decreased rapidly year after year owing to the appearance of the stern trawler and the decrease of average catch of all the vessels.
