Photoperiod Alters the Critical Swimming Speed of Juvenile Largemouth Bass, Micropterus salmoides, Acclimated to Cold Water

The objective of this research was to determine whether the critical swimming speed of juvenile largemouth bass, Micropterus salmoides, was influenced by prolonged exposure to seasonally inconsistent photoperiods. To test this hypothesis, the critical swimming speeds (U,,i3 of fish laboratory acclimated to 5, 10, 15, or 19 C, and seasonally consistent or 12:12 light-dark photoperiods, were compared to that of field-acclimatized bass. In early winter the U,,, of largemouth bass laboratory acclimated to 5 C and a 12:12 light-dark photoperiod was significantly reduced relative to that of fish field acclimatized to 5 C but was not significantly different when compared to that of fish acclimated to 5 C and a seasonally consistent 9:15 light-dark photoperiod. In early summer the U,,, of largemouth bass laboratory acclimated to 10 C and a 12:12 light-dark photoperiod