琵琶湖の重要水産魚種「ホンモロコ」の産卵環境を科学的に解明~産卵に配慮した湖の水位操作によるホンモロコの資源回復に期待~

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2025-04-17 京都大学

京都大学と近畿大学、滋賀県水産試験場の研究グループは、琵琶湖の重要水産魚種ホンモロコが、ヤナギの根が繁茂する浅瀬かつ波当たりの良い場所を産卵場に選んでいることを科学的に解明しました。特に産卵盛期の5~6月に水位が低下すると、卵が干出し死滅する可能性があり、水位の安定的な維持が必要とされます。この知見は、産卵環境に配慮した湖の水位管理によってホンモロコ資源の回復につながることが期待されます。

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琵琶湖の抽水帯周辺におけるホンモロコの産卵環境選択性 Spawning habitat selectivity of Honmoroko (Gnathopogon caerulescens) around the emergent vegetation zone of Lake Biwa, central Japan

Banri Koda,Keita Takasaku,Daisuke Ishizaki,Yoshiaki Kai & Takeshi Kikko

Fisheries Science  Published:17 April 2025

DOI:https://doi.org/10.1007/s12562-025-01874-6

琵琶湖の重要水産魚種「ホンモロコ」の産卵環境を科学的に解明~産卵に配慮した湖の水位操作によるホンモロコの資源回復に期待~

Abstract

Honmoroko (Gnathopogon caerulescens), an endangered species endemic to Lake Biwa, is adversely affected by the desiccation of eggs caused by the water level management and deterioration of spawning habitats (lakeshore vegetation zone). Despite a recent study of foreshore spawning of the species having suggested that some local environmental conditions may be related to foreshore spawning habitats selection by the species, no quantitative studies have examined the conditions that determine the suitability of such habitats. The present survey of Honmoroko eggs around emergent vegetation zones along the foreshore in two study areas indicated that Honmoroko selectively spawn at shallow sites with greater water velocity, utilizing emergent plants, such as Salix spp.. The findings confirmed the importance of protecting the spawning habitats around the Lake Biwa shoreline and have important implications for the controlled management of Lake Biwa water levels with regard to Honmoroko spawning.

1404水産水域環境
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