Sound production of humpback whales, Megaptera novaeangliae, in Alaskan waters

Abstract

Underwater sounds of feeding humpback whales were recorded 90–130 km south of Juneau in August, 1975. Although there were scattered grunts, yelps, moans, and low-frequency narrow-band pulses, as expected, the most pervasive sounds were trains of 25–80 Hz broadband pulses that had a mean repetition rate of 1 per sec. They were superposed on 40ndash;1250-Hz continuous noise which swelled and decayed as pulse trains began and ended, varying in duration from 15 to 100 sec. Incidental sounds made by surfaced animals were shrieks and trumpeting made through the blowholes and wide-band pulses produced by flipper or tail slaps on the water's surface. Also recorded were weaker wide-band pulse trains that were characterized by (1) Lack of energy below 500 Hz, (2) uneven amplitude and repetition interval, and (3) repetition rate of several per sec. The source of these pulses was believed to be clashing of baleen plates from wave action as a whale skimmed food organisms at the surface. Estimated maximum underwater source levels (referred to 1 μ Pa at 1 m) were grunt, 190 dB; trumpeting, 185 dB; tail slap, 183 dB; shriek, 180 dB; and low-frequency broadband pulse, 176 dB.