Otolith shape differed among Florida largemouth bassMicropterus salrnoides floridanus, northern largemouth bassM. s. salrnoides, and the first-generation (F1) hybrid between these two subspecies. As fish grew, Florida largemouth bass otoliths became progressively longer along the anterior axis and less wide along the dorsal axis than those of the northern subspecies; otolith measurements of F1hybrids were intermediate between those of the two subspecies. Computations of back-calculated lengths that disregard these variations in the relationships of body length to anterior otolith radius and body length to dorsal otolith radius could cause bias in comparative age and growth studies, especially in newly established multistock populations. Because the differences in otolith morphometry were more evident along the dorsal plane, greater sources of error may be encountered when otoliths must be sectioned and measured than when whole-view measurements are used.