EFFECTS OF DIFFERENT EXERCISE CONDITIONING VELOCITIES ON THE ENERGY RESERVES AND SWIMMING STRESS RESPONSES 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 ). Exercise conditioning at the moderate velocity increased body weigh t and standard length. Lipid contents and wet weight lipid percentages in the carcass were higher in the moderate- and fast-velocity fish th an in the controls, and dry weight lipid percentages in the carcass an d whole fish at the moderate velocity were higher than in those condit ioned at the fast velocity. Moderate-velocity fish had resting (nonstr essed) cortisol levels lower than those in the controls. After swimmin g stress, plasma cortisol, lactate, osmolality, and hematocrit levels in all fish were very high with no significant differences among treat ments, while muscle pH values in all fish were lower than those in res ting fish. Within the post-swimming stressed fish, muscle pH was lower in the controls than in those conditioned at the fast velocity. Overa ll, exercise conditioning in the moderate to fast velocity range incre ased body lipids and decreased post-swimming stress acidosis in young- of-the-year striped bass.