Nesting activity, parental care behavior, and reproductive success of smallmouth bass, Micropterus dolomieu, in an unstable thermal environment

Abstract

Temperature plays a critical role in the reproductive ecology of smallmouth bass, affecting factors such as the timing of spawning, offspring development and survival of the brood. Because temperature also influences the activity rates of fish, it has the potential to alter the chronology of parental care activities and possibly the immediate or future reproductive success of individual fish. We conducted a study in a thermal effluent canal on Lake Erie to examine the influence of fluctuating thermal regimes on parental care and reproductive success of smallmouth bass. In general, parental care activity of these smallmouth bass was higher than previously reported for non-thermally altered environments and did not follow conventional stage-specific patterns. In fact, individual fish exhibited very different patterns, with no consistency among individuals. Despite these behavioral alterations and the thermal instability in the canal, the reproductive success of smallmouth bass (i.e., the percentage of nesting males that successfully produced free-swimming fry) was high relative to other published values. Behavioral alterations observed were variable and did not conform with theory. However, the high level of reproductive success implies that fish are capable of adjusting energetic expenditures in response to a suite of conditions and risks.