Optimum Exercise Conditioning Velocity for Growth, Muscular Development, and Swimming Performance in Young-of-the-Year Striped Bass (Morone saxatilis)

Abstract

Young-of-the-year striped bass (Morone saxatilis) were exercise conditioned 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 (critical swimming velocity) was done at 50 and 60 d of the exercise conditioning 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 persisting 56 d post-conditioning. Fish exercised at the moderate and fast velocities 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 fish at any velocity showed a significant increase in the red to white muscle ratio at the end of 60 d of conditioning. Our data suggest that exercise-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.