EFFECTS OF PHOTOPERIOD AND TEMPERATURE ON SWIMMING PERFORMANCE OF WHITE CRAPPIE

Photoperiod and temperature are two environmental factors that have si gnificant effects on fish physiology and behavior but few studies have investigated the effect of photoperiod on swimming performance. We st udied the effects of five photoperiods, designated 24L:0D (24 h light: 0 h dark), 16L:8D, 12L:12D, 8L:16D, 0L:24D, and three temperatures (5, 15, and 25 degrees C) on the swimming performance of white crappie Po moxis annularis (5-11 cm in standard length) in a swim tunnel with pro peller-driven flow. Two-factor analysis of variance (alpha = 0.05) ind icated that both photoperiod and temperature significantly affected fi sh swimming performance but the interaction of photoperiod and tempera ture did not. At all temperatures, the 8L:16D photoperiod resulted in the highest mean swimming speeds. In addition, the temperature effect was consistent at all photoperiods. The mean swimming speed at 5 degre es C was significantly slower than at 15 degrees C or 25 degrees C; ho wever there was no significant difference between swimming speeds at 1 5 degrees C and 25 degrees C. Our documentation of a photoperiod effec t on fish provide further confirmation of the importance of this envir onmental variable on swimming performance.