Topic outline

  • Damage by harbor seals in fixed nets

    Currently, many regions in the Northern Hemisphere are facing the challenge of balancing stable conservation management with reducing the impact of marine mammals on fisheries, and Japan is also facing a similar challenge. In Hokkaido, damage to fisheries by pinnipeds such as sea lions, seals (spotted seals and harbor seals), and fur seals is a serious problem. The main types of these mammals that cause damage vary by area of the sea. On the Sea of Japan and Sea of Okhotsk sides, damage by Steller's sea lions is common, while on the Pacific Ocean side, damage by seals (mainly harbor seals) is common. The Oyashio region along the eastern coast of Hokkaido facing the Pacific Ocean (hereafter referred to as the "eastern Hokkaido coast") is one of the most productive marine areas, and many marine animals use this region as their feeding grounds. The harbor seals is the only marine mammal that lives and breeds along the coast of this region. Of the 11 known haulout sites of the harbor seals in Hokkaido, 10 sites are located along the east coast of Hokkaido from Kushiro to Nemuro, and the remaining one is around Cape Erimo. Damage caused by the harbor seals is particularly noticeable in salmon set nets that are set up for a certain period in coastal areas. Fishermen call such damage "tokkari-gui," and most of the salmon caught in the set nets sometimes suffered from this type of damage.