OPTIMUM EXERCISE CONDITIONING VELOCITY FOR GROWTH, MUSCULAR DEVELOPMENT, AND SWIMMING PERFORMANCE IN YOUNG-OF-THE-YEAR STRIPED BASS (MORONE-SAXATILIS)

Young-of-the-year striped bass (Morone saxatilis) were exercise condit ioned for 60 d at four different water velocities: <0.02 (control), 0. 5-1.2 (slow), 1.5-2.4 (moderate), and 2.4-3.6 body lengths.s(-1) (fast ). Sampling for growth (body weight change), muscular development (red and white muscle cross-sectional areas), and swimming performance (cr itical swimming velocity) was done at 50 and 60 d of the exercise cond itioning period and at 14, 28, 42, and 56 d post-conditioning. Optimum conditioning velocities for growth and swimming performance were the moderate and fast velocities, respectively, with both effects persisti ng 56 d post-conditioning. Fish exercised at the moderate and fast vel ocities showed significant increases in red muscle areas (at 0 and 14 d post-conditioning, respectively) and in white muscle areas (at 0-28 and 14-28 d post-conditioning, respectively). Exercise-conditioned fis h at any velocity showed a significant increase in the red to white mu scle ratio at the end of 60 d of conditioning. Our data suggest that e xercise-conditioned young-of-the-year striped bass would have size and swimming advantages consistent with higher survival than unexercised fish when stocked in natural ecosystems.