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Spatial niche partitioning among three small cetaceans in the eastern coastal area of Hokkaido, Japan

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Title: Spatial niche partitioning among three small cetaceans in the eastern coastal area of Hokkaido, Japan
Authors: Iwahara, Yuka Browse this author
Shirakawa, Hokuto Browse this author
Miyashita, Kazushi Browse this author →KAKEN DB
Mitani, Yoko Browse this author →KAKEN DB
Keywords: Spatial niche partitioning
Small cetaceans
Prey distribution
Pacific white-sided dolphin
Dall's porpoise
Harbor porpoises
Issue Date: 5-Mar-2020
Publisher: Inter-Research
Journal Title: Marine ecology progress series
Volume: 637
Start Page: 209
End Page: 223
Publisher DOI: 10.3354/meps13232
Abstract: Spatial niche partitioning of marine mammals is thought to be caused by dietary differences. However, due to the difficulty involved with conducting simultaneous marine predator and prey distribution surveys at the same scale, marine mammals have not been studied alongside their prey distribution. To understand the spatial niche overlap between 3 small cetaceans observed in the eastern coastal waters of Hokkaido, Japan (Pacific white-sided dolphin Lagenorhynchus obliquidens, Dall's porpoise Phocoenoides dalli, and harbor porpoise Phocoena phocoena), and the mechanisms behind the differences in their distributions, visual and hydroacoustic surveys using a quantitative echosounder were concurrently conducted. A clear spatial niche overlap was observed between the Pacific white-sided dolphin and Dall's porpoise, whereas the spatial overlap was moderate between the harbor porpoise and the other 2 species. In areas where Pacific white-sided dolphins were observed, potential prey was abundant in a shallower layer, at approximately 80-90 m depth. On the other hand, potential prey was more abundant in deeper layers in areas where Dall's and harbor porpoises were observed. Water depth affected the potential prey abundance at all depth layers (0-300 m), as potential prey were more abundant in areas with a shallower water depth. Additionally, potential prey were more abundant in shallower layers (3-200 m) than in deeper layers (200-300 m), where the maximum water depth was 3000 m. The differences in spatial niche among Pacific white-sided dolphin, Dall's porpoise, and harbor porpoise might cause their dietary differences, as they are epipelagic feeders, midwater feeders, and both epipelagic and midwater feeders, respectively.
Type: article (author version)
Appears in Collections:北方生物圏フィールド科学センター (Field Science Center for Northern Biosphere) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 三谷 曜子

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