The end of silent predators: First cases of active sound production in batoids from the Mediterranean Sea and its potential implications

Abstract

[EN] The production of sound in terrestrial animals has been extensively studied, yet documentation of sound production in fish remains comparatively limited. Furthermore, certain groups such as elasmobranchs have traditionally been regarded as silent predators. This study presents two cases of active sound production in batoids, marking the first documented records in the Mediterranean Sea. Between November and December of 2023, multiple encounters with batoids were observed in the important shark and ray area of Marina Alta, Spain. Four distinct species were documented, with active sound production, in the form of clicks, recorded in two species: the rough skate, Raja radula, and the marbled electric ray, Torpedo marmorata. These clicks were produced while opening and closing their mouths, accompanied by the movement of their pectoral fins, both cases presumably associated with an agonistic display of defense against the divers, perceived as a threat. The clicks were produced when the threat was close, and as it moved away from the divers, the frequency of the clicks decreased until they ceased.