Hydrophone Identification of Spawning Sites of Spotted Seatrout Cynoscion nebulosus (Osteichthyes: Sciaenidae) Near Charleston, South Carolina

Abstract

Spawning male spotted seatrout, Cynoscion nebulosus , produce distinctive drumming sounds by compressing the swim bladder with the surrounding muscles to attract mates during their spawning season. Four distinctive sounds have been described: 1) a "grunt" followed by a series of "knocks," 2) "aggregated grunts," 3) a "long grunt," and 4) a "staccato." Cynoscion nebulosus spawn about once every 16 to 21 days from April through September in South Carolina, USA. The initiation, duration, and site of spawning is influenced by environmental and temporal variables. We described the environmental conditions at ten drumming locations by identifying sound producing individuals and aggregations with a hydrophone. We verified spawning activity by collection of recently spawned Cynoscion nebulosus eggs in three locations were we recorded drumming activity