Early growth and survival of striped bass, Morone saxatilis (Walbaum), and its phenotypically similar hybrid (M. saxatilis x M. chrysops) using an otolith marking method.

An experiment using differently marked larval striped bass, Morone saxatilis (Walbaum), and its hybrid (M. saxatilis x M. chrysops (Rafinesque)) was performed in two grow-out ponds. Larval striped bass were immersed in oxytetracycline solution to mark their otoliths; hybrids received no treatment. Larvae from both groups were mixed and stocked at 8 days post hatch into the ponds. Striped bass and hybrid larvae grew to a significantly larger size at 3 5 days in one pond. In both ponds, hybrid lengths at 3 5 days after hatch were significantly greater than striped bass lengths. However, the magnitude of the size difference between hybrids and striped bass was twofold greater (10%) in one pond than in the other (5%). The proportion of striped bass juveniles at 3 5 days differed from the initial stocking proportion (0.5 3) only in one pond, where hybrids showed 12% greater survival than striped bass. Results suggested that the relative survival of hybrids was influenced by growth conditions in the ponds. Based on the ease of protocol and analysis of the marking experiment, we recommend its use to (1) investigate relative performance between genetic groups of young fish in common environments; and (2) predict the effects of introductions of genetically altered fishes. [ABSTRACT FROM AUTHOR]