Previous studies have shown that the critical swimming speed (Ucnt) of largemouth bass, Micropterus salmoides Lacépède, is significantly influenced by a number of factors including body mass (Beamish, 1970), training (Farlinger and Beamish, 1978), water temperature (Hocutt, 1973; Kolok, 1991) and photoperiod (Kolok, 1991). These studies share a common approach in that they were primarily concerned with comparing mean values of Ucrit of fish from different treatment groups, and individual variation within the groups was treated as statistical noise. While this approach is valid, it may overlook a significant source of performance variation - the variation found among individuals.
Recent research (for a review, see Bennett, 1987) into the locomotor performance of amphibians and reptiles has suggested that individual variation is substantial and repeatable (i.e. performance variation of an individual forced to perform multiple times will...
