Types, distribution, and seasonal occurrence of sounds attributed to Bryde’s whales (Balaenoptera edeni) recorded in the eastern tropical Pacific, 1999–2001

Abstract

Vocalizations resembling known Bryde's whale sounds were recorded on autonomous hydrophones at seven sites in the eastern tropical Pacific. Five short (<3 s) low-frequency (<80 Hz) "phrase" types were observed. "Swept alternating tonal" phrases included a 37-Hz tone and often a 25-16-Hz downswept tone, while "nonswept alternating tonal" phrases had a predominant tone at 29 Hz and often additional tones at 16 and 47 Hz. Alternating tonal phrases were found in 79% of the total hours in which phrases were detected, and occurred primarily at the eastern hydrophone sites. "Burst-tonal" phrases included tones that were often preceded by a wideband burst of noise. The "low burst-tonal" phrase contained tones at 19 and 30 Hz, and was detected at five of the hydrophone sites. The "high burst-tonal" phrase included a 42-Hz tone and was observed only on the northwestern hydrophones. A single "harmonic tone" phrase type was observed that included a fundamental tone at 26 Hz and at least two harmonics; this phrase was observed exclusively at the eastern hydrophone stations. This opportunistic survey has shown that acoustics is an effective means of studying this poorly understood, pelagic balaenopterid.

An acoustic survey of baleen whales off Great Barrier Island, New Zealand

“…A very similar call was subsequently correlated to Bryde's whales by Oleson et al (2003) in the Eastern tropical Pacific and the geographic range of similar calls was extended westward across the Pacific by Heimlich et al (2005). Helweg (1998) suggested a nocturnal or crepuscular pattern occurred in these calls in October, but not during July-August, the two time periods examined in that study.…”

“…The different geographic distributions of Bryde's whale call types Heimlich et al 2005) suggests the utility of call type in determining stocks and identifying new species, although more study is needed. The two different call types produced each by Bryde's whales and blue whales at this site, may allow future real time direction of small vessels to animals of a known call type such that genetics sampling can be combined with acoustics to provide a better understanding of these calls.…”

“…Helweg (1998) suggested a nocturnal or crepuscular pattern occurred in these calls in October, but not during July-August, the two time periods examined in that study. Oleson et al (2003) named a very similar call "Be3" and Heimlich et al (2005) referred to a similar call as "low-burst tonal". The calls described here are similar but not exactly the same as either the Be3 or the low-burst tonal.…”

“…The 12-h interval used here equates to an average straight line travel speed of 3.25km/h and an estimated average detection zone radius of 45 km. Kibblewhite et al 1967;McDonald et al in press Sirovic et al 2004;McDonald et al in press Cummings & Thompson 1971;McDonald et al 2001;Oleson 2005Thompson et al 1996Thode et al 2000Watkins et al 1987Croll et al 2002Thompson et al 1992McDonald et al 1995;McDonald & Fox 1999Kibblewhite et al 1967Winn et al 1981;Cerchio et al 2001Heiweg 1998Oleson et al 2003;Heimlich et al 2005 522 New …”

Low frequency vocalizations attributed to sei whales (Balaenoptera borealis)

“…Recordings of baleen whale vocalizations have been used to assess abundance ͑George et al, 2004͒, seasonal occurrence ͑Stafford et al, 2001Heimlich et al, 2005;Mellinger et al, 2007͒, distribution ͑Stafford et al, 2001Heimlich et al, 2005͒, andbehavior ͑Croll et al, 2002;Darling et al, 2006;Oleson et al, 2007;Stimpert et al, 2007͒. These studies rely on very fundamental information about which species produce particular calls.…”