Northbound migration of a humpback whale Megaptera novaeangliae along the Pacific coast of Japan.

Abstract

Photo-identification (photo-ID) using natural markings is useful for population studies, especially of the humpback whale Megaptera novaeangliae. In the North Pacific, 2,712 different individuals were identified. Using photographs taken during 1991, 1992 and 1993, their annual migration was analysed and their abundance estimated by Calambokidis et al. (1997). Earlier knowledge on the distribution of North Pacific humpback whales was based on commercial whaling records (this species was hunted until 1965) (Johnson and Wolman 1984). In the western North Pacific, humpbacks wintered off the Ryukyu Islands (where they were hunted in the 1950s), the Bonin Islands (1920s-1940s), and Taiwan (1920s-1950s) (Nishiwaki 1959; Wang 1985). Wintering off Taiwan was not reconfirmed until recently. More recently, another wintering ground was newly found around the northern Philippine Islands (Yaptinchay 1999). In spring, humpback whales are believed to migrate to feeding grounds such in the Okhotsk Sea, the Bering Sea, the waters southeast of the Aleutian Islands, and northeast of Honshu Island (Japan) (Johnson and Wolman 1984). Here we report multiple sightings of a humpback whale along the Pacific coast of Japan during a single northbound migration season.