Thermal preferenda of northern, florida, and reciprocal f₁ hybrid largemouth bass

Four genetically confirmed stocks of largemouth bass Micropterus salmoides (northern and Florida subspecies and both reciprocal subspecific F₁ hybrids) were evaluated to assess their thermoregulatory behavioral differences. Acute testing methods were used to determine thermal preferenda at seven acclimation temperatures ranging from 8 to 32°C. Linear regression analyses of these data demonstrated that preferred temperature varied with acclimation temperature. However, there were no significant differences in the final preferred temperature observed among the stocks during either the spring or the fall testing period. This similarity among final preferred temperatures indicates that these determinations may not be appropriate predictors of temperatures that govern other temperature-dependent physiological characteristics, such as reproduction and optimal growth.