ゴマフアザラシ:冬季北海道回遊群の周年定着個体の削減による被害軽減のための管理へ

摘要

Until 1970s, spotted seals were rarely seen on the Japan Sea side of Hokkaido. However, significant change in the ecology of spotted seals were observed in recent years; such as extension of their distribution range to the North, increase in their population number, lengthening of their period of stay in Hokkaido, and adult seals were started to be seen in the area which were not common in the past. Consequently, fisheries damage have become more serious in the past few years. Although culling reduced the number of seals in the coverage area, it only had a temporal effect and in fact, it even made the animals stay longer in the area and use different site as haul out locations. As a result, the number of individuals seen annually are started to increase and are reported in different sites. Since reducing the number of seals in the area cannot prevent the damage, Spotted Seal Management Plan was established in 2014 and the action was taking place since April 2015 for two year span. There are increase in the number of animals which were staying in the area throughout the year. Since reduction in the number of resident seals are less likely to have effect on the total population persistence, population control on these individuals will be taking place from June to October. The aim of the management is to reduce the number of the seals to halve of the counts taken in 2013 at Rebun Island, Wakkanai (Koeto, Souya, Bakkai), Teuri Island and Yagishiri Island, by the summer 2017.