| Project/Area Number |
16K20883
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| Research Category |
Grant-in-Aid for Young Scientists (B)
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| Allocation Type | Multi-year Fund |
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| Research Field |
Ecology/Environment
Conservation of biological resources
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| Research Institution | Hokkaido University |
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Principal Investigator |
KOBAYASHI yumi 北海道大学, 農学研究院, 研究員 (30634737)
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| Project Period (FY) |
2016-04-01 – 2020-03-31
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| Project Status |
Completed (Fiscal Year 2019)
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| Budget Amount *help |
¥4,160,000 (Direct Cost: ¥3,200,000、Indirect Cost: ¥960,000)
Fiscal Year 2018: ¥780,000 (Direct Cost: ¥600,000、Indirect Cost: ¥180,000)
Fiscal Year 2017: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2016: ¥2,470,000 (Direct Cost: ¥1,900,000、Indirect Cost: ¥570,000)
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| Keywords | 個体群動態 / 海生哺乳類 / 鰭脚類 / 北海道 / 野生動物管理 / ゼニガタアザラシ / 個体数 / トレンド / 哺乳類 / アザラシ / 海洋環境変化 / 長寿命 / 個体識別 / 漁業被害 / 希少種 / 人間との軋轢 / 個体数推定 / 生態学 / 動物 / 保全 |
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| Outline of Final Research Achievements |
The Kuril harbor seal Phoca vitulina stejnegeri is an only living year round marine mammal in southeastern Hokkaido, Japan. Its population declined the early 1970s, the causes of this decline are thought to be commercial harvesting, bycatch in fishing, and other human activities.The average population growth rate was approximately 3-5%, per annum over the past 40 years.Commercial harvesting ended in the late 1980s and probably had the effect of population trends until the late 1980s.The bycatch of seals in now remained similar to or slightly greater than that during the 1980s.Bycatch prevention measures can also reduce fishery damage.The local set net fishermen try are improving fishing gear at the site continues.
The number of harbor seals has not increased since around 2010.It was suggested that the survival rate of pups and subadult class may be decreased under the influence of recent marine environmental changes.
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| Academic Significance and Societal Importance of the Research Achievements |
日本に生息する唯一の鰭脚類であるゼニガタアザラシは，1970年代に人間による過度の狩猟により絶滅の危機に瀕したが，その後に個体数が回復してきた経緯を持つ．本研究では，本種の過去から現在までの分布と個体数変動をまとめた．個体数は過去30年間では約3倍に増えたが，近年は，海洋環境変動の影響を受けて増加していないことが示唆された．また，初期死亡率は平均20－40％，最大で70％であるが，成獣以降の生存率が90％以上で，またメス成獣は高い割合（70%以上）で子を持つといった生活史パターンを明らかにした．これらのデータは，本種の今後の管理を進めていくにあたり，学術的にも社会的にも貢献する．
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