Survey of the number of seals incidentally caught by salmon trap nets along the coastal waters of the Nossapu Cap in Nemuro Peninsula from 2002 to 2003 compared with the survey from 1982 to 1983

DOI Web Site 12 References
  • Kobayashi Mari
    Laboratory of Aquatic Management, Department of Aqua-Bioscience and Industry, Faculty of Bioindustry, Tokyo University of Agriculture Marine Wildlife Center of Japan (Incorporated Non Profit Organization/NPO)
  • Ishinazaka Tsuyoshi
    Rausu Ministry of the Environment
  • Kakumoto Chiharu
    Marine Wildlife Center of Japan (Incorporated Non Profit Organization/NPO)
  • Wakatabe Hisashi
    Marine Wildlife Center of Japan (Incorporated Non Profit Organization/NPO)
  • Kobayashi Yumi
    Graduate School of Fisheries Sciences & Faculty of Fisheries, Hokkaido University
  • Shimizu Akiko
    Marine Wildlife Center of Japan (Incorporated Non Profit Organization/NPO)

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Other Title
  • 根室半島・納沙布岬におけるサケ定置網によるアザラシ類の 2002–2003年混獲数調査
  • 根室半島・納沙布岬におけるサケ定置網によるアザラシ類の2002-2003年混獲数調査--1982-1983年調査と比較して
  • ネムロ ハントウ ノサップ ミサキ ニ オケル サケ テイチアミ ニ ヨル アザラシルイ ノ 2002 2003ネン コンカクスウ チョウサ 1982 1983ネン チョウサ ト ヒカクシテ
  • ～1982–1983年調査と比較して～

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Abstract

A total of 261 seals were incidentally caught by 15 salmon trap nets of the Habomai Fisheries Cooperative Association from September to November in 2002 and 2003 (00 years’ survey). No difference was found between the number of seals in the 00 year’s survey and the number (272 seals) in the survey from September to November in 1982 and 1983 (80 years’ survey). No differences were found in species ratio [dominant and the next species were harbor (Phoca vitulina stejnegeri) and spotted seals (P. largha)], and in the positions of salmon trap nets in which most of the seals were incidentally caught between both surveys, respectively. However, there was a significant difference between the rates of harbor and spotted seals of all incidentally caught animals between both surveys (91.2% and 7.7% in the 00 years’ survey and 77.6% and 20.6% in the 80 years’ survey, respectively). The frequency distribution of incidentally caught seals showed two peaks in the middle of September and November in the 80 years’ survey, the other side, a peak in the beginning of September when the salmon trap net fishery started with gradual decrease until November in the 00 years’ survey. The distribution centers of harbor seals and spotted seals are thought to be in the southern area of the Kuril Islands, especially concentrated in Habomai and Shikotan Islands. Therefore, further research on the relationship between the East-Hokkaido group and the Habomai-Shikotan group are necessary to their conservation.<br>

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