Importance of walleye pollock (Theragra chalcogramma) to wintering ribbon seals (Phoca fasciata) in Nemuro Strait, Hokkaido Japan

• Deguchi Tomohiro

  Laboratory of Marine Ecology, Graduate School of Fisheries Sciences, Hokkaido University

• Goto Yoko

  Laboratory of Marine Ecology, Graduate School of Fisheries Sciences, Hokkaido University

• Sakurai Yasunori

  Laboratory of Marine Ecology, Graduate School of Fisheries Sciences, Hokkaido University

抄録

Many ribbon seals (Phoca fasciata) appear in winter in Nemuro Strait, eastern Hokkaido. We propose that their presence is partly related to an exploitation of the large numbers of spawning walleye pollock (Theragra chalcogramma). To investigate feeding habits of ribbon seals in winter, we sampled stomachs from seals for prey composition and size taken in the strait from February–April 1996–1998. Nine fish and five squid species were identified from sixty-four seal stomachs. Walleye pollock and magistrate armhook squid (Berryteuthis magister) were predominant in the diet of seals each year. The index of relative importance of prey showed that walleye pollock was the most dominant prey item. Most pollock eaten by seals had reached maturity. Prey distribution suggested that ribbon seals foraged in the intermediate-bottom layer of the continental slope water. No differences were found between prey composition and size of male and female ribbon seals. Subadult and adult ribbon seals consumed more pollock and less squid than young seals, which also tended to consume smaller pollock. Pinpoint lanternfish (Lampanyctus regalis) and saffron cod (Eleginus gracilis) occurred only in stomachs of adults and young, respectively. Foraging technique and diving ability may explain the differences in prey composition and size among seal age classes.<br>

収録刊行物

• Mammal Study

  Mammal Study 29 (1), 55-63, 2004

  日本哺乳類学会

キーワード

• magistrate armhook squid
• stomach contents

詳細情報

• CRID: 1390001204673674240
• NII論文ID: 10013281270
• NII書誌ID: AA11185060
• DOI: 10.3106/mammalstudy.29.55
• ISSN: 13486160
• ISSN: 13434152
• NDL書誌ID: 6989573
• Web Site: https://ndlsearch.ndl.go.jp/books/R000000004-I6989573
• Web Site: https://www.jstage.jst.go.jp/article/mammalstudy/29/1/29_1_55/_pdf/-char/en
• 本文言語コード: en
• データソース種別:
  • JaLC
  • NDL
  • Crossref
  • CiNii Articles
• 抄録ライセンスフラグ: 使用不可