Sei whale sounds recorded in the Antarctic

Abstract

Sei whales are the least well known acoustically of all the rorquals, with only two brief descriptions of their calls previously reported. Recordings of low-frequency tonal and frequency swept calls were made near a group of four or five sei whales in waters west of the Antarctic Peninsula on 19 February 2003. These whales also produced broadband sounds which can be described as growls or whooshes. Many of the tonal and frequency swept calls ͑30 out of 68͒ consist of multiple parts with a frequency step between the two parts, this being the most unique characteristic of the calls, allowing them to be distinguished from the calls of other whale species. The average duration of the tonal calls is 0.45± 0.3 s and the average frequency is 433± 192 Hz. Using a calibrated seafloor recorder to determine the absolute calibration of a sonobuoy system, the maximum source level of the tonal calls was 156± 3.6 dB re 1 Pa at 1 m. Each call had different character and there was no temporal pattern in the calling.

Review of Underwater and In-Air Sounds Emitted by Australian and Antarctic Marine Mammals

“…Very brief (0.03-0.04 s) high-frequency (1.5-3.5 kHz) downsweeps occurring in bouts of 10-20 have been reported from Nova Scotia [11] and also been described as a series of pulses with peak energy at 3 kHz and 7-10 pulses over 0.7 s [12]. Broadband (100-800 Hz) pulsed sounds of 1-3-s duration have also been documented [60]. …”

“…Acoustic recordings exist from the North Atlantic, off the US east coast [54][55][56] and Nova Scotia, Canada [11,12], off the Azores [57], from Hawaii [58], south of New Zealand [59] and Antarctica [60]. There are no recordings of sei whales in Australian waters with simultaneous visual species identification.…”

“…The most frequently reported sounds are simple FM sounds: upsweeps and downsweeps, lasting 0.7-2.2 s, with the fundamental covering a low-frequency band Hz; [54][55][56][57][58][59]) or mid-frequency band (200-600 Hz; [60]). These FM sounds have been recorded with and without harmonics.…”

“…These FM sounds have been recorded with and without harmonics. Source levels of FM and CW sounds are 147-183 dB re 1 µPa rms @ 1 m [ [55][56][57]60]. Very brief (0.03-0.04 s) high-frequency (1.5-3.5 kHz) downsweeps occurring in bouts of 10-20 have been reported from Nova Scotia [11] and also been described as a series of pulses with peak energy at 3 kHz and 7-10 pulses over 0.7 s [12].…”

Low frequency vocalizations attributed to sei whales (Balaenoptera borealis)

“…Thompson et al ͑1979͒ described recordings of sei whales obtained in the waters between Nova Scotia and Newfoundland, Canada, as 0.7 s long bursts of seven to ten metallic pulses with peak energy at 3 kHz. Knowlton et al ͑1991͒ described similar 1.4-2.6 s midfrequency vocalizations recorded in waters off southwestern Nova Scotia, Canada that consisted of two bouts of 10-20 frequency-modulated ͑FM͒ 1.5-3.5 kHz sweeps separated by 0.4-1 s. In the Southern Ocean near the Antarctic Peninsula, McDonald et al ͑2005͒ recorded a number of tonal, FM, and broadband calls between 200 and 700 Hz in proximity to sei whales. The estimated source level of these calls was relatively low for baleen whales ͑156 dB with regard to 1 Pa at 1 m͒, and…”