Sex- and state-dependent attraction of round gobies, Neogobius melanostomus, to conspecific calls

Abstract

Acoustic communication is of fundamental importance in many fish species but it is often unclear what information is present in different calls and how responsiveness varies with reproductive state and the sex of the receiver. The current study investigates reproductive flexibility in acoustic responsiveness through differential attraction between reproductive morphs of the round goby (Neogobius melanostomus) to conspecific calls. Parental male (PM) round gobies emit calls and females respond to these calls with high specificity. We used playback experiments to determine the response of gobies to recordings of two conspecific calls, a grunt and a drum. For the grunt, reproductive females (RF) displayed a significantly higher response for first approach than non-reproductive males (NRM), but RFs never responded to the drum call. Upon examining within-morph responses for time spent at a playing speaker, RFs were found to spend the longest time at the grunt call compared to other sound types. In contrast to the female responses, NRMs and sneaker males (SM) displayed a strong preference to the drum call. Overall these results support that the grunt could be for mate attraction while NRMs and SMs may be eavesdropping on the drum call. By determining the relationship between reproductive state and responses to conspecific calls, we show that reproductive state is a critical factor in understanding behavioural responses in fish.