Case study of discards problems of stationary trap net in Taiji, Wakayama Japan

One major fishery in the coastal area of Japan uses a stationary trap net, which employs many sub type of net designed for each target species. The catch of this fishery in Wakayama is about 2700 t, which is almost 0.5% of the total stationay net catch (6000,000 t) in 1996. This study was conducted on a stationary trap net operated in Taiji Bay ( N33 deg 36' E135 deg 58' ), on the east coast of Kii Peninsula, Wakayama, Japan. The daily catch data indicated that over 40 species had been caught throughout the observation period ( 13 July - 18 November 1998). The main commercial species in the area are Sahyraena japoica, Trachrus japonicus, Prionurus scalprus, Seplioteuhis lessoniana, Scombrops boops, Cypselurus agoo agoo, C. poecilopterus, and Trichiurus lepturus. Both the catch composition and quantity vary depending on the season. Consequently, we emphasize that this fishery has in effect been capturing multispecies. Nonetheless, it remains necessary to provide cost - effective methods and thechniques to minimize waste at this fishery. However, the evidence indicates that it is very difficult to collect useful data under actual conditions. The most serious difficulty is encountered during the selection process. Commonly, both the commercial and non-commercial species and requirements as regards both size and species. Decisions about the selection is an important issue for this particular fishery because the catch is diversified depending on the passive catching method used. Of course, the selection of species varies every day according to the divesity of species caught. In the area, the amount of discards has decreased and there has been an increase in the total catch. There is no relationship between the number of discards and number of species caught. It is assumed that the number of discards has averaged out to be 10 - 30% of the total catch for a particular period. This report provides one example of how selection for nultispecies has been achieved in this area.