Distribution of the spotted seal Phoca largha along the coast of Hokkaido, Japan

Abstract

The distribution of the spotted seal, Phoca largha, along the coast of Hokkaido was investigated, based on personal interviews, surveys of haul-out sites, and records and direct examinations of seals. Interviews conducted in 1997 along the entire coastline of Hokkaido, confirmed that spotted seals have been observed in all eight regions of the island. Incidental harvests by fishing nets and damage control kills were confirmed in seven and in three regions, respectively. Examinations were made of live and dead specimens, and of specimen records from between 1971 and 1998 (n=605), all obtained from Hokkaido University, aquariums and zoos. Specimen and documentary records were most common in regions where incidental harvests and damage control kills were reported. Seasonal and regional variations in seal distributions were observed. Incidental harvests, damage control kills, and strandings were most common during salmon harvest season (fall), sea ice season, and the weaning period, respectively. Sub-adults and adults were found in areas with seasonal sea ice, while immature seals were recovered from areas with little or no sea ice. The fewest seal sightings and no haul-out sites were reported from southern Hokkaido, probably because warm sea currents discourage seals from using this area.