オオクチバスは生け簀の水温の変化によってストレスを受ける(Live well temperature variations stress out largemouth bass, study finds)

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2025-07-08 イリノイ大学アーバナ・シャンペーン校

オオクチバスは生け簀の水温の変化によってストレスを受ける(Live well temperature variations stress out largemouth bass, study finds)
Researcher Allison Hay studying largemouth bass.

イリノイ大学の研究によると、釣り大会で使用される生け簀内の水温変動がオオクチバスにストレスを与え、生理的回復を遅らせることが明らかになった。現場および実験室での調査では、水温が±5℃以上変動すると、血中のホルモンや代謝物に影響が出る一方、反射機能や致死率に即時的な変化は見られなかった。氷の投入や水の循環が急激な温度変化を引き起こす原因とされた。研究者は、生け簀の水温は湖水と一致させるべきと提言し、魚の健康維持には安定した温度管理が重要だと結論づけている。

<関連情報>

生け簀内の温度変化がオオクチバスに与える影響の定量化 Quantifying the impact of temperature variation in live wells on Largemouth Bass

Allison A Hay , Jackson C Glomb , Reagan E Oller , Cory D Suski
North American Journal of Fisheries Management  Published:02 May 2025
DOI:https://doi.org/10.1093/najfmt/vqaf016

ABSTRACT

Objective

Live-well confinement can place multiple sublethal stressors on captured fish that can prolong the time for recovery and contribute to the likelihood of tournament-related mortality. The goal of this study was to quantify water temperatures in live-release tournaments across multiple seasons and then use this information to quantify the impacts of thermal conditions on Largemouth Bass Micropterus nigricans during live-well holding.

Methods

To define thermal conditions during live-well holding and the influence of these thermal conditions on Largemouth Bass, a series of complementary field and laboratory studies were conducted. The field study quantified the temperature of live wells in several live-release angling tournaments. The laboratory study used the temperature data from the field to inform holding condition treatments and subsequently quantify the physiological changes in Largemouth Bass induced by thermal conditions in live wells.

Results

Results from the field showed that thermal conditions in live wells were highly variable, both within and across anglers and tournaments. Several trends in thermal patterns were observed. Laboratory simulations of these patterns showed that cyclical cooling of 4–5°C simulating multiple additions of ice during holding resulted in considerable physiological disturbance and impaired recovery for Largemouth Bass. Disturbances also increased in simulations that increased live-well temperature. Reflex impairment indices were not influenced by any treatment.

Conclusions

Thermally dynamic recovery environments induce physiological disturbances and prolong recovery from exercise and should be avoided. Given the intense tournament pressure in this system and throughout North America, our results identify key practices that could mitigate tournament practices that would inhibit Largemouth Bass recovery from tournament activities.

1401漁業及び増養殖
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