Complex acoustic signaling in the toadfish, Opsanus tau

Abstract

Male oyster toadfish, Opsanus tau, produce long duration (250 to 650 ms) sexual advertisement calls or “boatwhistles” during the breeding season. When males are in close proximity, they employ multiple vocalization strategies. They normally alternate the production of boatwhistles to avoid temporal overlap. When the fundamental frequencies of multiple callers vary by more than 10 Hz, the frequency is correlated strongly with water temperature. However, when conspecifics with similar frequencies vocalized, the individuals shifted their fundamental frequencies independent of water temperature in a jamming avoidance response. Males also emit a single, short duration pulse or “grunt” (~100 ms), which are emitted almost exclusively during the boatwhistle of a conspecific male which can jam the signal. The disruptive grunt specifically targeted the second stage or tonal portion of the boatwhistle, believed to be the primary acoustic attractant for females, and its brevity and precision may allow its emitter to remain undetectable. While the acoustic repertoire of teleost fishes may be less diverse compared with terrestrial species, the toadfish can detect conspecific signals and employ different strategies to avoid temporal and frequency overlap, thus displaying a capacity for complex acoustic interactions.