Analysis of the 20-Hz Signals of Finback Whales (Balaenoptera physalus).

• Main Authors: Watkins, William A, Tyack, Peter, Moore, Karen E, Bird, James E
• Other Authors: WOODS HOLE OCEANOGRAPHIC INSTITUTION MA
• Format: Text
• Language: English
• Published: 1985
• Subjects: Biological Oceanography; Acoustics; *WHALES; *MARINE BIOLOGY; *AUDITORY SIGNALS; *MARINE BIOLOGICAL NOISE; ACOUSTIC DATA; UNDERWATER ACOUSTICS; BEHAVIORAL SCIENCE; FREQUENCY; BERMUDA; GEOGRAPHY; HYDROPHONES; POSITION(LOCATION); PULSE SPACING MODULATION; REPRODUCTION(PHYSIOLOGY); SEASONS; SIGNALS; SOUND; WINTER; WUNR104809; Balaenoptera physalus
• Online Access: http://www.dtic.mil/docs/citations/ADA183747; http://oai.dtic.mil/oai/oai?&verb=getRecord&metadataPrefix=html&identifier=ADA183747

The 20-Hz signals of finback whales (Balaenoptera physalus) were analyzed from more than 25 years of recordings at a variety of geographic locations on near-surface hydrophones close to whales and on deep hydrophone systems. These signals were composed of 1-sec pulses of sinusoidal waveform with downward sweeping frequency from approximately 23 to 18 Hz at variable levels up to 186 dB (re 1 uPa), usually with slightly lower levels for the pulses at the beginning and end of sequences. These pulses were produced in bouts lasting as long as 32.5 hrs, composed of regularly repeated pulses at intervals of 7 to 26 sec, either at one pulse rate or at two alternating (doublet) pulse intervals. The signal bouts were interrupted by rests of 1-20 min at roughly 15-min intervals and by irregular gaps lasting between 20 and 120 min. The distribution of these signals throughout the year and the signal sequences were analyzed from the continuous drum records of the Bermuda SOFAR Station (Patterson and Hamilton, 1964). These signals occured during winter, sometimes beginning in September and ending in May. The sound sequences were never exactly replicated. The direct association of the signals with the reproductive season for this species points to the 20-Hz signals as possible reproductive displays by finback whales. Keywords: Marine biology.