2018 Volume 82 Issue 1 Pages 1-13
Understanding the overall fishery and fish stock trends from commercial fisheries data throughout Japan is important for discussing the concrete management policy of the Japanese fishery. In this study, fishery information from logbook data of offshore trawl fisheries throughout Japan were compiled into a database with spatial and temporal criterion (logbook database). The temporal transitions of the catch, effort (number of tows) and standardized catch per unit effort (CPUE, kg/tow), and the spatial changes of the fishing grounds were revealed using this database. Additionally, the impacts of various factors (transitions of domestic and international social situations, developments of fishing vessels and gears, fish stock fluctuation, and so on) on these changes were discussed, and the problems for the quantitative evaluation of the overall fisheries and stock conditions were indicated. After 1972, the catch and number of tows in most areas have decreased, and the fishing grounds were reduced to the coast of Japan. The catch and number of tows in some areas were attuned to the fish stock fluctuation due to environmental changes. On the other hand, the CPUEs remained stable on a long-term basis. These CPUE trends were probably affected by the changes in the fishing strategies, the vessel sizes, and so on. In the future, it will be possible to evaluate the overall fishery and stock conditions from the logbook database by standardizing fishing effort and investigating the catch data.
