About 40 percent of the global marine catch is caught unintentionally, a study group of the global conservation group WWF said Wednesday, estimating the amount is at least 38 million tons a year.
A paper issued by the group said unintentionally caught fish and other marine animals are "either unmanaged or unused" and should be considered bycatch, which occurs because most fishing gear is nonselective and fishing fleets can catch marine life other than the targeted species.
Bycatch is "an issue of critical ocean conservation and resource management concern," the paper said.
"The extent of bycatch . . . is revealed as potentially so serious that it must become a major political, management, sectoral and environmental focus, bringing its implications to the fore as a conservation/food security imperative," it said.
Robin Davies, a group member, called for the need to develop fishing equipment that curbs bycatch and urged Japanese to pay attention to how fish are caught.
The estimates in the paper were worked out by mainly using data available for 23 major fishing countries, including Japan, between 2000 and 2003. It also included data on global shark and tuna fishing.
The results identified 38.5 million tons of annual bycatch, which represents 40.4 percent of the estimated annual global catch of 95.2 million tons.
The paper also showed about 90 percent of marine life caught in shark fin fishing is bycatch.
Japan's bycatch rate is 13 percent, lower than the global average, it said.
The figures should be seen only as "indicative minimum bycatch estimates" because several sources of potentially large amounts of bycatch have not been estimated due to data deficiencies, the group said.
Large-scale bycatch of turtles, seabirds and other species is not usually quantified, the paper said.
