Metabolic costs of sound production in the oyster toadfish,Opsanus tau

Abstract

The energetics of mate calling has been studied in insects, frogs, birds, and mammals, but not in fishes. The oyster toadfish, Opsanus tau, produces a boatwhistle advertisement call using one of the fastest muscles known in vertebrates. Because toadfish will not boatwhistle in a respirometer, we measured oxygen consumption after eliciting sound production by electrically stimulating the sonic swim bladder muscle nerve. Induced sounds were similar to a male calling at a rapid rate. Stimulation of the sonic nerve increased the respiration rate by 40–60% in males, but they became agitated. Repeating the experiment decreased agitation, and in most fish respiration rates approximated control levels by the second or third replication. Elicited sounds and therefore sonic-muscle performance were similar in all repetitions, hence it appears that the increased oxygen consumption in the first trial was caused by the fish's agitation. Controls indicated that electrode implantation and electrical stimulation of the body cavity did not affect the respiration rate. We suggest that allocation of a small amount of the total energy budget to sound production is reasonable in toadfish, and probably most other fish species, because of the small amount of time that the sonic muscles actually contract and their small size (about 1% of body mass).