Fall distribution and diversity of cetaceans along the southern and eastern coasts of Hokkaido, Japan

Abstract

The southern and eastern coasts of Hokkaido, part of the western North Pacific and the southern Sea of Okhotsk, are productive regions with a high degree of biodiversity and human activity. This area is an important habitat for cetaceans. However, only a few studies have been conducted on comprehensive species co-inhabiting the study area at the same time. Information regarding cetacean distribution patterns is necessary for ecosystem management and marine conservation. The objective of this study was to investigate the distribution patterns and environmental variables affecting the distribution of cetaceans in coastal Hokkaido using sighting surveys. Five baleen and seven toothed whale species were observed during the study period. The maximum entropy model used to map the distribution of 11 selected cetacean species showed a heterogeneous distribution, which may reflect a potentially suitable habitat for each species. In the North Pacific region, there are differences in water temperature between east and west of Cape Erimo, which is possibly the reason why some species are only distributed in the eastern side. In the Nemuro Strait, the distribution differs from north to south, likely influenced by seafloor topography. Our results will help to clarify the habitat of various cetacean species in coastal Hokkaido and provide essential information for their conservation.