なぜ漁業は魚の豊富さの変動を拡大するのか
Christian N K Anderson1, Chih-hao Hsieh, Stuart A Sandin
1Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California 92093, USA.
Nature
|April 19, 2008
まとめ
漁業により,魚の個体数が不安定になる可能性があります. この研究は,漁業の圧力や環境追跡ではなく,搾取された魚の貯蔵量の年齢削減が,漁業における人口の不安定性とブーム・バストサイクルを根本的に推進していることを明らかにしています.
科学分野:
- マリン・バイオロジー マリン・バイオロジー
- 漁業 科学 漁業 科学
- 人口のダイナミクス
背景:
- 漁獲された個体群は,漁獲されていない個体群よりも大きな変動を示すが,その根本的な原因は不明である.
- この変動性を説明する3つの仮説があります:漁業圧力による直接的な影響,平均体サイズ/年齢の減少,および年齢によって切り離された魚群における人口動態の変化です.
研究 の 目的:
- 漁獲集団における時間的な変動の増大を誘発するメカニズムを調査する.
- 長期的な漁業データを用いて,直接的な漁業効果,環境追跡,および人口動態の変化を区別する.
主な方法:
- カリフォルニア協同海洋漁業調査 (CalCOFI) の50年間の魚の幼虫記録の分析.
- 漁獲魚群の個体数の変動に関する3つの競合する仮説の評価.
主要な成果:
- 変動する漁力の圧力によって,人口の変動が直接増加するという証拠は存在しない.
- 限られた証拠によると,商業漁業は平均体サイズと年齢を低下させ,環境トラッキングを直接導きます.
- 強い証拠は,年齢によって切り離された集団が,人口統計的パラメータの変化により不安定な動態を示すことを示しています.
結論:
- カリフォルニアの時間的変動の増大 現在の漁業は,直接の搾取や環境追跡ではなく,人口動態の固有の不安定性から生じている.
- 選択的採集は,基本的人口動態を変え,ブーム・バストサイクルと潜在的な貯蔵量の減少につながります.
- この発見は,持続可能な漁業資源管理に重大な影響を及ぼします.
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