The effect of body size on post-exercise physiology in largemouth bass.

Variation in individual size has important consequences for a number of characteristics of fish, which can impact fish populations. The impact of fish size on recovery following exercise, however, is poorly understood, with little information existing on the recovery of ionic/osmotic variables. The goal of this study was to quantify not only how allometry impacts the magnitude of physiological disturbance following burst exercise in largemouth bass (Micropterus salmoides), but also how allometry impacts the time required for exercise-induced disturbances to return to baseline levels. To accomplish this goal, two size classes of largemouth bass (large = 772-1,441 g total weight, mean = 1,125 g; small = 93-238 g, mean = 148 g) were exercised for 60 s and allowed to recover for 0, 1, 2, or 4 h before being sampled for plasma and white muscle. Large largemouth bass exhibited elevated concentrations of plasma glucose and sodium relative to small fish following a common exercise challenge. Large fish required additional time to clear metabolic disturbances in plasma and failed to restore potassium to basal levels even following 4 h of recovery, indicating an improved ability of the smaller fish to recover from disturbances. Results are further discussed in the context of physiological ecology and fitness for largemouth bass.