ML116456

影音備註

BAY: xNOTES: NML studies. 5. Field investigations, Cape Canaveral to Narragansett Bay and Chesapeake Bay to Solomons, Md., May-July, 1964-66: distinctive, knocking pulses associated with the breeding period, usually produced in bursts of ca. 0.5 sec to several seconds duration with similar intervals between bursts. Individual fish may repeat this sequence for several minutes and remain silent for a shorter period before beginning again. Pulse repitition rate much slower than for Cynoscion regalis, ranging between 5-10 pulses/sec, with 8/sec common...Maximum sound production usually two hours before to two hours after sunset, often starting with random single or double knocks and graduallt forming longer bursts. In area of huge concentration (e.g., mouth of Chesapeake Bay), evening chorus merges into a steady roar with sound pressure to 100 microbars. Cyclic effects often observed after sunset with abrupt drops in noise level lasting up to thirty second as a result of coincident silent periods within large schools. Fish, M.P. and W.H. Mowbray. 1970. Sounds of the Western North Atlantic fishes: a reference file of biological underwater sounds. Johns Hopkins Press. Baltimore. p. 99.