Colleagues,
This recently published article is available online. Of particular interest
were acoustic detections of pygmy blue whale sounds in the Southern Ocean; the
first published descriptions of new Ross seal vocalizations; the far northerly
distribution of leopard seal detections; and the regional 'dialect' associated
with fin whale song. The abstract follows with more details.
Gedamke, J. and Robinson, S.M. 2010. Acoustic survey for marine mammal
occurrence and distribution off East Antarctica (30-80°E) in January-February
2006. Deep Sea Research Part II: Topical Studies in Oceanography Volume 57,
Issues 9-10, May 2010, Pages 968-981.
If interested, you can download it at
http://dx.doi.org/10.1016/j.dsr2.2008.10.042
or request it by contacting me directly.
Cheers,
Jason
Abstract
A large scale, systematic, acoustic survey for whales and seals in eastern
Antarctic waters was conducted in January-February 2006. During the BROKE-West
survey of Southern Ocean waters between 30 and 80° E longitude, an acoustic
survey was conducted to complement a traditional visual survey for marine
mammal occurrence and distribution. As part of the survey, 145 DIFAR sonobuoys
were deployed every 30' of latitude on north-south transects, and prior to CTD
stations on the initial east-west transect. Underwater sound was analyzed for
70 minute samples from each sonobuoy. Blue whales were the most commonly
recorded species, identified at 55 of the sonobuoy deployment sites. Other
species recorded include: sperm (46 sites), fin (14), humpback (2), and sei (3)
whales, and leopard (11) and Ross (17) seals. Large numbers of blue and sperm
whales, and all Ross seals were detected on the westernmost two transects,
which were the only transects of the survey with relatively extensive sea ice
remaining off the continental shelf. Large numbers of blue whales were also
detected in the more eastern waters of the survey off the Prydz Bay region,
while two detections of pygmy blue whales represent the farthest south these
whales have been recorded. Of the relatively few fin whale detections, most
occurred in more northerly waters. Fin whale vocalizations from this region
were distinctly different than those recorded elsewhere around Antarctica
suggesting acoustic recordings may be useful to delineate regional or stock
boundaries of this species. Previously undescribed sounds were attributed to
Ross seals. Acoustic detections of these and leopard seal sounds indicate these
animals venture further from their traditionally described distributions, with
vocalizing leopard seals occurring much further north than might be expected.
Overall, the results of the sonobuoy survey provide a measure of each species'
relative spatial distribution over the survey area based on acoustic
detections, and when combined with the results of the visual survey, will
provide a comprehensive view of marine mammal distribution throughout the
region during the BROKE-West survey.
____________________________
Jason Gedamke, PhD
Australian Marine Mammal Centre
Australian Antarctic Division
203 Channel Highway
Kingston, TAS 7050
ph: +61 (0)3 6232 3153
mob: +61 (0)4 0938 8990
fax: +61 (0)3 6232 3449
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