MANAGEMENT OF LONGLINE FISHERY TO MITIGATE INTERACTIONS WITH ECOLOGICALLY RELATED SPECIES

Abstract

Longline fishery has been regarded as an environmentally friendly fishing method. However, recently, there is a growing concern over the impact of longline fishing on untargeted marine species. Sharks are often claimed to be susceptible to heavy fishing pressure judging from their large body size and low fecundity. But our analysis of fishing data indicated that catch rates of pelagic shark species showed no signs of decrease and that their stocks were in sound condition. Further stock assessment of sharks and management of longline fishery are important to solve the shark problem. Large scavenging seabirds, mostly albatrosses and petrels, are incidentally taken in tuna longline fishery at the sea surface near fishing vessels. Since introduction of mitigation measures to the limited risky zone around the operating fishing vessels can effectively reduce incidental catches of seabirds, Japan has been making efforts to develop mitigation measures and to promote their prevalent use. Sea turtles are also taken incidentally in longline fishery and the impacts of incidental catch have been claimed as a cause of decline in some populations. However, comprehensive management of marine and terrestrial environment is indispensable for the conservation of sea turtles because various factors are affecting them other than fisheries. Japan made a proposal to implement a plan of action for the conservation of sea turtles at FAO-COFI in 2001. Although the proposal was not accepted, research and development have been initiated in Japan for the solution of sea turtle issue. Since information is still deficient for many sea turtle populations in Asia, international co-operation of Asian countries for research and management is very important for the sustainable co-existence of sea turtles and human activities