Meeting Abstract
During the mating season, male Oyster Toadfish (Opsanus tau) establish nesting sites and produce courtship calls called boatwhistles to attract females. The boatwhistle consists of a broadband grant followed by a longer tonal segment that male fish will produce from mid-May to mid-August. The fundamental frequency of the tonal portion of the call is correlated with water temperature; it is thought that females are attracted to this portion of the call. Females must localize the call to find the nest and deposit the eggs which the male guard throughout development. Males also will produce short grunts to jam the tonal portion of rival males’ calls. The toadfish population in Eel Pond was monitored acoustically throughout the mating season using a linear hydrophone array. Pure tones and boatwhistle calls were broadcast using an underwater speaker at four different frequencies (150 Hz, 175 Hz, 200 Hz, and 225 Hz) to determine the effect of extraneous sound on the number and timing of toadfish calls. Toadfish were more responsive to lower frequency sounds (150 Hz) early in the season when the water was 19°C. However, as the water temperature increased to 22°C, they shifted their responses to higher frequencies (200 Hz and 225 Hz). The results show that boatwhistle production will increase in response to both pure tone and boatwhistle playback. Additionally, as the fundamental frequency of their own calls increase with rising water temperature, so does their response to higher frequency calls.
