Sei whale sounds recorded in the Antarctic

Area of Science:

• Marine biology
• Bioacoustics
• Cetacean research

Background:

• Sei whales (Balaenoptera borealis) are among the least acoustically understood rorquals.
• Previous acoustic data on sei whales is limited to two brief call descriptions.

Purpose of the Study:

• To acoustically characterize sei whale vocalizations.
• To identify unique features of sei whale calls for species identification.

Main Methods:

• Acoustic recordings were collected near a group of sei whales west of the Antarctic Peninsula.
• Low-frequency tonal, frequency-swept, and broadband (growl/whoosh) sounds were documented.
• A calibrated seafloor recorder and sonobuoy system were used for sound level calibration.

Main Results:

• Sixty-eight tonal and frequency-swept calls were recorded, with 30 exhibiting a unique frequency step between call parts.
• Average duration of tonal calls was 0.45 ± 0.3 s, with an average frequency of 433 ± 192 Hz.
• Maximum source level for tonal calls was 156 ± 3.6 dB re 1 µPa at 1 m; calls lacked a temporal pattern.

Conclusions:

• The frequency-stepped calls are a distinguishing characteristic of sei whale vocalizations.
• This study provides significant new data on sei whale acoustics, aiding in species identification and behavioral studies.