Analysis and Ranking of the Acoustic Disturbance Potential of ...

Report No. 6945
BBN Systems and Technologies Corporation
most sounds were below 2 kHz (Dahlheim et al. 1984; Moore and Ljungblad 1984).
Higher frequency clicks are produced by calves (Table 2.8; Fish et al. 1974;
Norris et al. 1977).
Sounds of the northern right whale have not been studied. This species
is now very rare in Alaskan waters. Sounds of southern right whales have most
of their energy at frequencies between 50 and 1000 Hz (Clark 1983).
Intensities are about 172 to 186 dB re 1 pPa at 1 m (Clark in Wiirsig et al.
1982). Simple sounds are used for long distance contact and complex sounds
are associated with socializing whales (Clark 1983).
Most bowhead calls are brief moans in the frequency range of 25 to 900 Hz
(Ljungblad et al. 1980; Wursig et al. 1985; Clark and Johnson 1984; Cummings
and Holliday 1987). However, some complex sounds have components up to 4 or
5 kHz. Source levels of bowhead calls have been estimated to range from 129
to 189 dB re 1 pPa at 1 m (Clark et al. 1986; Cummings and Holliday 1987). The
functions and behavioral significance of the sounds are, for the most part,
unknown.
2.2.3 Pinnipeds
Most pinniped sounds (Table 2.9) are associated with agonistic displays,
establishment of dominance and/or territory, and mating displays. In the
northern fur seal, Steller sea lion, harbor seal and walrus, in-air vocal
communications between mother and pup are established soon after birth and may
be important in establishment of the mother/pup bond and for identification
and location of the pup (Peterson 1968; ~chusterman 1981 ; Miller 1985; Renouf
1984) .
The underwater sounds of the Steller sea lion and of the northern fur
seal are not well known. They consist of barks, clicks and bleating sounds
(Schusterman et a1 . 1966 ; Poulter 1968; Schusterman and Balliet 1969 ; Cummings
and Fish 1971). Frequency, source level information, and behavioral
significance of these underwater sounds are unknown.
The bearded seal produces a distinctive musical trill, primarily in he
spring. The trill generally begins at about 2.5 kHz, sweeps upward to 3 kHz,
descends to 1 kHz with an upsweep to 2 kHz, and then descends below 1 kHz (Ray
et al. 1969). A 0.5 to 1 kHz frequency modulation is superimposed on the
center frequency. The trill ends with a pure tone descending-from 500 to
200 Hz. The song is thought to be a territorial advertisement and/or mating
call of the male (Ray et al. 1969). Source levels of bearded seal songs have
not been reported but these songs are a prominent feature of the underwater
acoustic environment of the arctic during spring.
The ribbon seal also produces a downward frequency sweep, but it does not
waver and it exhibits several harmonics (Watkins and Ray 1977). Sounds are in
the range of 100 to 7100 Hz with estimated source levels of 160 dB re 1 uPa at
1 m (Watkins and Ray 1977).
Ringed seals make low intensity clicks with a fundamental frequency of
4 kHz and barks, yelps, and growls with most energy below 5 kHz (Schevill et