Abstract
A total of 261 seals were incidentally caught by 15 salmon trap nets of the Habomai Fisheries Cooperative Association from September to November in 2002 and 2003 (00 years’ survey). No difference was found between the number of seals in the 00 year’s survey and the number (272 seals) in the survey from September to November in 1982 and 1983 (80 years’ survey). No differences were found in species ratio [dominant and the next species were harbor (Phoca vitulina stejnegeri) and spotted seals (P. largha)], and in the positions of salmon trap nets in which most of the seals were incidentally caught between both surveys, respectively. However, there was a significant difference between the rates of harbor and spotted seals of all incidentally caught animals between both surveys (91.2% and 7.7% in the 00 years’ survey and 77.6% and 20.6% in the 80 years’ survey, respectively). The frequency distribution of incidentally caught seals showed two peaks in the middle of September and November in the 80 years’ survey, the other side, a peak in the beginning of September when the salmon trap net fishery started with gradual decrease until November in the 00 years’ survey. The distribution centers of harbor seals and spotted seals are thought to be in the southern area of the Kuril Islands, especially concentrated in Habomai and Shikotan Islands. Therefore, further research on the relationship between the East-Hokkaido group and the Habomai-Shikotan group are necessary to their conservation.
