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Interannual fluctuations in recruitment of walleye pollock in the Oyashio region related to environmental changes

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Title: Interannual fluctuations in recruitment of walleye pollock in the Oyashio region related to environmental changes
Authors: Shida, Osamu Browse this author
Hamatsu, Tomonori Browse this author
Nishimura, Akira Browse this author
Suzaki, Akifumi Browse this author
Yamamoto, Jun Browse this author
Miyashita, Kazushi Browse this author →KAKEN DB
Sakurai, Yasunori Browse this author →KAKEN DB
Keywords: climate changes
environmental conditions
water temperature
Walleye pollock
Funka Bay
Tohoku region
Pacific coast of eastern Hokkaido (Doto area)
Issue Date: Nov-2007
Publisher: Pergamon
Journal Title: Deep Sea Research. Part 2, Topical Studies in Oceanography
Volume: 54
Issue: 23-26
Start Page: 2822
End Page: 2831
Publisher DOI: 10.1016/j.dsr2.2007.09.001
Abstract: The Japanese Pacific walleye pollock (Theragra chalcogramma) stock is the largest stock of this species in Japanese waters. It is a key component of the Oyashio ecosystem. In southern Hokkaido waters, these fish spawn mainly during January and February near the mouth of Funka Bay (FB), and most eggs and larvae are transported into FB. During midsummer juvenile pollock migrate along the southern coast of Hokkaido to a nursery ground on the continental shelf off eastern Hokkaido (Doto area). However, some eggs and larvae are transported southward to the Tohoku region (TR). Transport depends largely on the Oyashio, which generally flows southward along the eastern coasts of Hokkaido and Tohoku. Thus, this stock has two different recruitment routes: FB–Doto and FB–TR. In the 1980s, when the southward flow of the Oyashio was strong, the number of age-2 pollock estimated from a virtual population analysis (VPA) indicated that recruitment to the entire stock remained at a medium level. In the 1990s, when the Oyashio weakened, strong year-classes occurred in 1991, 1994, and 1995, but not in the latter half of the 1990s. Juvenile catches in the TR by commercial fisheries, which can be taken as indices of recruitment level via FB-TR, were high during the 1980s and decreased in the 1990s. Although there was no significant difference in the average number of recruits between the 1980s and the 1990s as estimated from a VPA, the recruitment patterns differed between the two decades. Here, we propose that recruitment routes of this stock shifted in response to environmental changes.
Type: article (author version)
Appears in Collections:水産科学院・水産科学研究院 (Graduate School of Fisheries Sciences / Faculty of Fisheries Sciences) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 桜井 泰憲

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