原著
2012年から2014年の北海道東部太平洋側における定置網による鰭脚類の混獲状況
2017 年 4 巻 2 号 p. 1-10
詳細
2017 年 4 巻 2 号 p. 1-10
The Pacific Ocean along the coast of eastern Hokkaido is rich in marine resources and many pinniped species inhabit the area. In this study, we report the pinniped numbers and species that are incidentally caught in salmon set nets in the waters off eastern Hokkaido from spring to autumn in 2012-2014.
As a result, the number of by-catch individuals was higher in spring than in autumn, with the majority of animals caught in Konbumori and Hamanaka, respectively. Individuals of all the pinniped species that inhabit the Hokkaido coast were caught in spring. The main seal species caught in this season were harbor seals, spotted seals, and northern fur seals, whereas the majority of by-catch animals in autumn were harbor seals. Most of the by-catch seals were young individuals. However, in addition to pups, pregnant northern fur seal females were caught incidentally, likely while moving northward to breed. Migratory pinnipeds depends on the environment, the change in the number of by-catch by year was great. In contrast, resident species changed little.
Therefore, status of the by-catch of migratory pinnipeds can be used as an indicator of environmental changes, whereas, the current inhabitant changes for resident species such as harbor seals.
