海洋前線は魚にとって楽園それとも障壁

2026-04-03 東京大学

東京大学の研究チームは、海洋前線(潮目)が魚にとって好漁場であるという従来の定説を再検証し、むしろ「障壁」として機能することを明らかにした。全球および北西太平洋の漁場データを解析した結果、前線内部での漁場形成は外側より5~20%程度多いにとどまり、従来考えられていたホットスポット効果は限定的であった。一方、暖水側と冷水側での漁場形成の差は15~70%と大きく、魚種ごとに分布が分断される障壁効果が顕著に確認された。この成果は、海洋前線が魚類の移動や分布を制約する重要な要因であることを示し、動的な漁業管理や資源保全戦略の高度化に貢献すると期待される。

海洋前線は魚にとって楽園それとも障壁
古典的な海洋前線と漁場の考え方(ホットスポット効果)と新たに確認された障壁効果

<関連情報>

海洋前線の障壁効果が過小評価され、世界の漁業分布に影響を与えている Underestimated barrier effects of ocean fronts shape global fishery distribution

Qinwang Xing,Zihui Gao,Shin-ichi Ito,Haiqing Yu,Bilin Liu,Heng Zhang,Xinjun Chen & Wei Yu
Nature Communications  Published:28 March 2026
DOI:https://doi.org/10.1038/s41467-026-71250-0  Unedited version

Abstract

Marine ecosystems exhibit high spatiotemporal heterogeneity, making it crucial to understand the mechanisms sustaining biological hotspots. Ocean fronts shape local biogeochemical processes and have long been recognized as biological hotspots aggregating organisms from phytoplankton to top predators and attracting fisheries (hotspot effects). However, fronts also exhibit pronounced environmental differences between their two sides (barrier effects), and how species and fishery distributions respond to these effects remains poorly understood. By integrating satellite-based front detection with commercial catch records, fishery-independent surveys, and global fishing datasets, we show that fishery distributions across diverse regions and major commercial stocks worldwide respond strongly to barrier effects, exhibiting 15–70% differences in distribution between the frontal warm and cold zones, driven by species-specific local thermal preferences. In contrast, responses to hotspot effects are generally sporadic with only 5–20% differences between frontal and non-frontal zones, and they emerge only when aggregations on one side of fronts offset avoidance on the other. This offset has led earlier studies to conservatively underestimate front-induced fishery variations by 55–75%. Our findings complement the traditional front-induced hotspot paradigm by clarifying the importance of barrier effects and underscore the need to reassess the role of ocean fronts in marine ecosystems.

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