DO NOT CITE WITHOUT PERMISSION SC/61/BRG3 1 An Update on Feeding by Bowhead Whales near an
Aerial surveys were conducted in the Central Beaufort Sea during late summer and early autumn of 2006-8 to monitor bowhead whale distribution during periods with and without seismic exploration. During some of the 2007-8 surveys large numbers of feeding bowhead whales were seen in an area where feed...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.541.1779 http://www.iwcoffice.co.uk/_documents/sci_com/SC61docs/SC-61-BRG3rev.pdf |
| Summary: | Aerial surveys were conducted in the Central Beaufort Sea during late summer and early autumn of 2006-8 to monitor bowhead whale distribution during periods with and without seismic exploration. During some of the 2007-8 surveys large numbers of feeding bowhead whales were seen in an area where feeding has been recorded in the past, but has not been common. Feeding bowheads appeared to remain in the same general area in the West sub-area of our Camden Bay survey grid for 16d in 2007 and for 6d in 2008 while seismic surveys were conducted 10-50km east of them. During feeding and travelling periods, averages of ~2,500 and ~350 bowhead whales were present in our survey area. The mean distance from the centre of the seismic survey area was not significantly different between periods with (51.4km) and without (49.6km) seismic during feeding periods, but the mean distance was significantly greater with seismic during travelling periods (51.5 vs 27.3km, respectively). During feeding periods, the highest sighting rates were recorded in the West sub-area in areas where seismic sounds were estimated to have been ≥120dB re 1 µPa (rms). During the travelling period, sighting rates in the sub-area that included the seismic operation declined as seismic exposure increased suggesting localized avoidance of seismic operations, but sighting rates were not significantly different among the East, Central and West sub-areas. Based on aerial sightings and observations from vessels, feeding bowheads appeared to tolerate seismic sounds until levels approached ~160dB but some feeding whales appear to have tolerated higher levels. One |
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