Optical and acoustic camera observations of the behavior of the Kuril harbor seal Phoca vitulina stejnegeri after invading a salmon setnet

Fujimori, Yasuzumi; Ochi, Yousuke; Yamasaki, Shintaro; Ito, Ryohei; Kobayashi, Yumi; Yamamoto, Jun; Tamaru, Osamu; Kuramoto, Yousuke; Sakurai, Yasunori

Optical and acoustic camera observations of the behavior of the Kuril harbor seal Phoca vitulina stejnegeri after invading a salmon setnet

Fujimori, Yasuzumi; Ochi, Yousuke; Yamasaki, Shintaro et al.

Fisheries science, 2018, 84(6), 953-961

Permalink : https://hdl.handle.net/2115/76034

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アクセス権	open access
URI	https://hdl.handle.net/2115/76034
タイトル	Optical and acoustic camera observations of the behavior of the Kuril harbor seal Phoca vitulina stejnegeri after invading a salmon setnet
著者	Fujimori, Yasuzumi ; Ochi, Yousuke ; Yamasaki, Shintaro ; Ito, Ryohei ; Kobayashi, Yumi ; Yamamoto, Jun ; Tamaru, Osamu ; Kuramoto, Yousuke ; Sakurai, Yasunori
e-Rad_Researcher 40261341 著者名 Fujimori, Yasuzumi
著者名 Ochi, Yousuke
著者名 Yamasaki, Shintaro
著者名 Ito, Ryohei
著者名 Kobayashi, Yumi
e-Rad_Researcher 10292004 著者名 Yamamoto, Jun
著者名 Tamaru, Osamu
著者名 Kuramoto, Yousuke
e-Rad_Researcher 30196133 著者名 Sakurai, Yasunori
言語	英語
キーワード	Fishery damage
	Haul out site
	Seal-fishery conflict
	Dual-frequency identification sonar
	Top predator
	Chum salmon
発行日	2018-11
出版者	Springer
収録物名	Fisheries science
巻(号)	84(6)
ページ	953-961
抄録	It has previously been confirmed that Kuril harbor seals Phoca vitulina stejnegeri cause damage to the chum salmon Oncorhynchus keta setnet fishery along the east coast of Hokkaido, Japan, but the level of damage has increased markedly with the recovery of their population in recent years. In this study, we attached an optical camera (Trawl Camera) and a dual-frequency identification sonar (DIDSON) acoustic camera to a setnet to observe the behavior of seals as they invaded the setnet, and to determine the number of salmon inside the net, to help inform the development of modified fishing gear. Salmon were observed at all times during daytime with the Trawl Camera, while seals were only observed once. Observations using the DIDSON in its low-frequency mode confirmed that the behavior of seals became vigorous from around sunset to nighttime within the recording time (1530-2100 hours). Observations using the DIDSON high-frequency mode showed that the overall lengths and body widths of seals ranged from 1.0 to 1.6 m and 0.15 to 0.35 m, respectively, while their swimming speeds ranged from 0.4 to 2.6 m/s, increasing around sunset and declining into the night. These results imply that seals mainly invade the setnet from evening to nighttime to predate on salmon.
資源タイプ	学術雑誌論文
出版タイプ	Accepted Manuscript
権利情報	The final publication is available at www.springerlink.com
	© [2018] 公益社団法人日本水産学会
	© [2018] The Japanese Society of Fisheries Science
PISSN	0919-9268
関連情報 (isVersionOf)	出版社版DOI https://doi.org/10.1007/s12562-018-1236-z