Behavioural thermoregulation of largemouth bass (Micropterus salmoides): response of naive fish to the thermal gradient in a nuclear reactor cooling reservoir

1.1. We studied patterns of temperature selection of naive largemouth bass (Micropterus salmoides) transplanted from an adjacent normothermic site to a cooling reservoir for a nuclear reactor Lethally hot (> 45°C) water entered the reservoir periodically.2.2. Temperature-sensing radio transmitters, which were surgically implanted in 10 fish, enabled us to monitor movement of bass during different times of year in the thermally heterogeneous environment.3.3. Naive bass exhibited a range of reactive thermoregulatory behaviours which led half of them to cool-water refuges in the reservoir. Moreover, some bass appeared to learn the thermal characteristics of the refuges.4.4. These behaviours were sufficient for 30% of the naive fish to survive extreme thermal conditions