Individual voices in a cluttered soundscape: acoustic ecology of the Bocon toadfish, Amphichthys cryptocentrus

Abstract

Toadfishes (family Batrachoididae) are a well-studied family of soniferous fishes, yet only a fraction of species within the family have been recorded, and only few detailed descriptions of calls exist. Here, we present the first description of the acoustic ecology of Amphyichtys cryptocentrus, a new-world toadfish species, distributed across the southern Caribbean Sea. We recorded fourteen individuals in a seagrass habitat over six nights in the Bocas del Toro Archipelago. Like other toadfishes, A. cryptocentrus produces compound calls with broadband and tonal components; a typical call contains 1–2 grunts, followed by 1–2 boops (average fundamental frequency = 112 Hz, average source level = 138 dB re:1 μPa RMS). While we observed relatively low between-individual variation in frequency components, our results show that individuals can be readily identified based on their call composition and call rate. This suggests that each toadfish has an individual “voice,” which may transmit selection-linked information to females about body condition, status, or motivation to mate. We also observed that toadfish produced grunts during neighbors’ calls, a previously-described aggressive behavior called “acoustic tagging”, which can intercept a potential rival’s mating advertisement. Our findings suggest that A. cryptocentrus (and its population in Bocas del Toro, in particular) represents a useful system for the study of fish bioacoustics and behavioral ecology, and we demonstrate that acoustic communication represents a major aspect of social behavior in coral reef fishes.