Ecological consequences of swim bladder noninflation for larval yellow perch

Swim bladder inflation is a fundamental developmental step during the larval stage of many fishes. Although the physiological mechanisms of swim bladder inflation are well documented, the ecological costs of noninflation are poorly understood. If high proportions of newly hatched fish larvae fail to inflate their swim bladders and swim bladder noninflation negatively affects individual survival probability, the population-level effects could be dramatic. To determine whether fish larvae without inflated swim bladders perform differently than their conspecifics with inflated swim bladders, we compared growth rate, feeding selectivity and efficiency, susceptibility to predation, oxygen consumption, and starvation mortality of two size-classes of larval yellow perch Perca flavescens with and without inflated swim bladders in a series of experiments. In the laboratory, growth rates of yellow perch with uninflated swim bladders were less than those for fish with inflated swim bladders, and fish with inflated swim bladders fed more efficiently than those with uninflated swim bladders. In addition, predation risk, metabolic demands, and vulnerability to starvation mortality were higher in fish lacking an inflated swim bladder than in fish with an inflated swim bladder. In the field, individuals with uninflated swim bladders were smaller than their conspecifics with inflated swim bladders. The relative occurrence of yellow perch larvae without inflated swim bladders declined as the sampling season progressed until only fish with inflated swim bladders were collected. Our results demonstrate that a larval yellow perch's failure to inflate its swim bladder results in a higher probability of dying. Thus, on the population scale, the factors affecting swim bladder inflation among larval fishes may have a profound effect on recruitment dynamics.