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Spatio-temporal Distribution of Bowhead Whales off Barrow, Alaska 2007-2012 (pg 1, 2, 3)

refer to caption  
Bowhead whales in an  ice lead during the spring migration. Photo by Vicki Beaver (NOAA/AFCS/NMML) Permit # 14245
 
acoustic recorder  
Acoustic recorder deployment. Photo by Amy Kennedy. (NOAA/AFSC/NMML)

 
 
Bowhead whale study area off Barrow, Alaska.


 

To minimize potential impacts from petroleum development activities in the Beaufort and Chukchi Seas, an increased understanding of bowhead whale behavior and distribution is needed. From 2007 to 2012, year-round autonomous passive acoustic recorders were deployed on subsurface moorings along the 100-m isobath from Point Barrow to Cape Halkett as part of the interdisciplinary Bowhead Whale Feeding Ecology Study (BOWFEST). These long-term recorders had a sampling rate of 8192 Hz and recorded on a 20%-45% duty cycle.

Over the course of the BOWFEST study period, 6,056 days of data recordings were collected. All recordings were reviewed for bowhead whale signals manually, on a 3-hour time interval. The spring migration was detected from 2009 through 2012 (earliest onset in 2011, latest in 2012). In all 4 years, a sudden and near-simultaneous onset of bowhead whale calling was observed at the long-term sites around the beginning of April.

Fall migration was detected in all 5 years of the study. The main pulse of the fall migration, however, had a lower peak and was more compressed in time than the spring migration peak. The end of the main pulse of calling for the fall migration varied between early November (2007) to mid-November (2008 to 2011).

Bowhead whale calls were recorded throughout the summer in the BOWFEST study area, not just during the spring and fall migrations, as had been previously believed. This can be seen most clearly in 2009 and 2011, where peak or near-peak presence continued between the migrations. (Work supported by BOEM/NOAA/NOPP)


BACKGROUND

  • BOWFEST study area: northern coast of Alaska out to 72°N and between 152°-157°W

  • Moorings deployed in four locations (M2-M5)

  • Triad of moorings at M2 lost in the 2008-2009 season

  • Results from M3 and M5 include data collected as part of National Ocean Partnership Program (NOPP) and Arctic Observing Network (AON) funded projects


METHODS

  • Autonomous passive acoustic recorders deployed yearly on 100m isobath

  • Sampling rate of 8192 Hz

  • 20-45% duty cycle

  • 6056 days of data collected

  • Data manually analyzed for bowhead whale calls

 

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