Seafloor acoustic recorders were recording offshore the West Antarctic Peninsula Region for three years beginning in March 2001 as part of a project funded by the National Science Foundation. We (John Hildebrand, Scripps Institution of Oceanography and Sue Moore, National Marine Fisheries Service) serviced the recorders once each year, replacing batteries and hard disks. We also recorded whales opportunistically with DIFAR sonobuoys on each voyage.
The ordinary blue whale is the most endangered mammal in the Antarctic, the recovery of which is in question. Pelagic whaling operations reduced the population from about 200,000 animals in 1910 to probably less than 1,000 in 1965, when the species was designated as protected from commercial whaling. So few visual sightings have been obtained from extensive visual survey cruises, that there may be a large error in population estimates.
In addition to producing ideal signals for long-range transmission, blue whale calls also vary significantly by population/geographic region. The distinctly different blue whale call character among different geographic areas provides a measure of populations within a species. Antarctic recordings include sounds from minke (photo at right), right, fin and humpback whales.
Incidental acoustic recordings of various species using sonobuoys is contributing to the acoustic subdivisions of these species, which ultimately may lead to splits in species and better definition of populations. Recording killer whales (photo on left) with camera and acoustics.
Publications which have resulted from this work to date include:
1. McDonald, M. A., Mesnick, S. L. and Hildebrand, J. A., Biogeographic characterisation of blue whale song worldwide: using song to identify populations, Journal of Cetacean Research and Management, 8(1):55-65, 2006.
2. McDonald, M. A., Thiele, D., Hildebrand, J. A., Wiggins, S. M., Moore, S. E. and Glasgow, D., Acoustic recordings of sei whales in the Antarctic, J. Acous. Soc. Am.,118, No. 6, 3941-3945, 2005. (Online. Opens pdf)
3. Širovic, A., Hildebrand, J.A., Wiggins, S. M., McDonald, M.A., Moore, S.M., and Thiele, D., Seasonality of blue and fin whale calls and the influence of sea ice in the Western Antarctic Peninsula, Deep Sea Research II. 51, 2327–2344, 2004. (Online. Opens pdf)
and more are yet to be completed.