ESR 24:61-72 (2014)  -  DOI: https://doi.org/10.3354/esr00553

Population trends of the Kuril harbour seal Phoca vitulina stejnegeri from 1974 to 2010 in southeastern Hokkaido, Japan

Yumi Kobayashi1,*, Tatsuya Kariya2, Jun Chishima2, Kei Fujii2, Kazuo Wada3, Shinya Baba1, Tetsuro Itoo4,†, Toshiyasu Nakaoka5, Miki Kawashima2, Sachiko Saito2, Noriyuki Aoki6, Shin-ichi Hayama7, Yuichi Osa8, Hidemi Osada2, Akio Niizuma9,†, Masatsugu Suzuki10, Yohjiro Uekane2,†, Kei Hayashi11, Mari Kobayashi12,13, Noriyuki Ohtaishi14, Yasunori Sakurai1

1Graduate School of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan
2Pinniped Research Group, Sapporo, Hokkaido 005-0018, Japan
3Primate Research Institute of Kyoto University, Inuyama, Aichi 484-8506, Japan
4North Pacific Pinniped Research Association, Gifu 501-1193, Japan
5Erimo Town Museum, Erimo, Hokkaido 058-0203, Japan
6Japanese Bird Banding Association, Nemuro, Hokkaido, 087-0036, Japan
7Center for Wildlife Conservation and Management, Nippon Veterinary and Animal Science University, Tokyo 180-8602, Japan
8Environmental and Geological Research Department, Institute of Environmental Sciences, Hokkaido Research Organization, Kushiro, Hokkaido 085-8588, Japan
9Faculty of Human and Social Studies, Keisen University, Tokyo 206-8586, Japan
10Department of Veterinary Medicine, Faculty of Applied Biological Sciences, Gifu University, Gifu 501-1193, Japan
11Kuril Harbour Seal Research Group, Obihirio University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-0835, Japan
12Department of Aqua-Bioscience and Industry, Faculty of Bioindustry, Tokyo University of Agriculture, Abashiri, Hokkaido 099-2493 Japan
13Marine Wildlife Center of Japan, Incorporated Non Profit Organization, Abashiri, Hokkaido 093-0042, Japan
14The Hokkaido University Museum, Sapporo, Hokkaido 060-0812, Japan
*Corresponding author: Deceased

ABSTRACT: The Kuril harbour seal Phoca vitulina stejnegeri is an endangered species which inhabits southeastern Hokkaido, Japan. Its population declined precipitously from between 1500 and 4800 individuals in the 1940s to a few hundred individuals in the early 1970s. The causes of this decline are thought to be commercial harvesting, bycatch in autumn set-net salmon fishing, and other human activities, including coastal fisheries. To quantify Kuril seal population trends, counts were performed each year at haul-out sites during the pupping season from 1974 to 2010 and during the moulting season from 1983 to 2010. The average population growth rate was ~4% per annum over the past 37 yr. Two haul-out sites (Kenbokki Island and Hattaushi) from which the species had disappeared in the early 1980s showed no evidence of being recolonized. Commercial harvesting ended in the late 1980s and probably had an effect on population trends until the 1990s. The bycatch of seals during autumn set-net salmon fishing in the 2000s remained similar to, or slightly greater than, that during the 1980s. Recently, seals have been observed at 9 haul-out sites during the pupping/moulting season along the coast of southeastern Hokkaido. Approximately 70% of the seals found were at Cape Erimo (~500 seals) and at Daikoku Island and Akkeshi (~250 seals).


KEY WORDS: Population counts · Bayesian state-space models · Conservation · Pinnipeds · Endangered species · Japan


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Cite this article as: Kobayashi Y, Kariya T, Chishima J, Fujii K and others (2014) Population trends of the Kuril harbour seal Phoca vitulina stejnegeri from 1974 to 2010 in southeastern Hokkaido, Japan. Endang Species Res 24:61-72. https://doi.org/10.3354/esr00553

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