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Project Description

This study of bowhead whale (Balaena mysticetus) feeding ecology (BOWFEST) will focus on late summer oceanography and prey densities relative to whale distribution over continental shelf waters north and east of Point Barrow, Alaska. Through NOAA's cooperative institutes, researchers will be included from Woods Hole Oceanographic Institute, University of Rhode Island, University of Alaska Fairbanks, University of Washington, and Oregon State University. Field work will be coordinated with the North Slope Borough, Alaska Eskimo Whaling Commission, Barrow Whaling Captains' Association, Alaska Department of Fish and Game, and Department of Interior's Minerals Management Service (MMS). Aerial surveys and acoustic monitoring will provide information on the spatial and temporal distribution of bowhead whales in the study area. Oceanographic sampling will help identify sources of zooplankton prey available to whales on the shelf and the association of this prey with physical (hydrography, currents) characteristics which may affect mechanisms of plankton aggregation. Prey distribution will be better understood by examining temporal and spatial scales of the hydrographic and velocity fields in the study area, particularly relative to frontal features. Results of this research program may help explain increased occurrences of bowheads feeding in the Western Beaufort Sea (US waters), well west of the typical summer feeding aggregations in the Canadian Beaufort Sea. Increased understanding of bowhead behavior and distribution is needed to minimize potential impacts from petroleum development activities.

Issues & Justification

Bowhead whale feeding activity has been well documented in the eastern Beaufort Sea (e.g., Richardson et al. 1987). There are also records of their presence during the summer in the northeastern Chukchi Sea (Moore 1992), and feeding activity has been observed in the western Beaufort Sea near Barrow in the spring (Carroll et al. 1987) and summer (George and Carroll 1989; Moore 1992), and such behavior is well known to Alaska Natives of the area. What is now needed is a more systematic, scientific approach to the relative scale of feeding and the consistency of this behavior relative to season, year, age-class, etc., along with relevant ecological parameters, such as bathymetry, currents, temperatures, ice conditions, and prey availability. Such a study has become more critical in light of the interests of petroleum development in the area. The more knowledge there is about bowhead use of the western Beaufort Sea, the better we will be able to find ways to minimize human impacts on these whales.

The purpose of this study is to provide and augment the scientific knowledge about bowhead whale feeding in the western Alaskan Beaufort Sea needed to support environmental risk assessments, Environmental Impact Assessments, and other pre-and post-leasing decision documents for potential gas and oil leasing in the Beaufort and Chukchi Sea Planning Areas.

Goals

  • Estimate patterns and variability in the timing and locations of feeding by individual bowhead whales and groups of bowhead whales.
  • Estimate temporal and spatial patterns of habitat use by bowhead whales.
  • Estimate bowhead whale prey distributions and abundance in the immediate vicinity of feeding bowhead whales. Make similar estimates in adjacent control areas away from feeding bowhead whales for comparison.
  • Estimate fine scale oceanographic and other relevant environmental conditions in the immediate vicinity of feeding bowhead whales. Make similar estimates in adjacent control areas away from feeding bowhead whales for comparison.
  • Estimate coarse scale ocean currents to characterize movement of water from the Chukchi Sea onto the Alaskan Beaufort Sea continental shelf.

Methods

This inter-disciplinary study shall be conducted on the continental shelf of the western Beaufort Sea between approximately 152A§ -157A§ west longitudes, and it shall integrate observations taken at two scales. At the fine scale, this study shall be designed to use adaptive project management to provide information on feeding bowhead whales that will be used in real time to plan and direct concurrent sampling of associated prey and oceanic conditions. Aircraft surveys will be used to locate whales, and photographs will be taken of individual whales to document feeding behaviors, to evaluate the stability of feeding group membership (within and between years), to estimate time spent using individual feeding sites, and to document individual or group movements between such sites. Once feeding whales are discovered, prey will be sampled in the water column and on the bottom, and oceanographic conditions will be characterized in the vicinity of the feeding sites. At the coarse scale, this study shall provide year-round information about ocean currents sufficient to detect and describe movements of water from the Chukchi Sea onto the Beaufort Sea continental shelf. Year-round information shall also be obtained on the presence and relative abundance of bowhead whales in the study area using various passive acoustic monitoring techniques. These data, plus other time-series information obtained from related studies of local knowledge and those employing satellite tracking and photo identification, will be integrated to provide an overall context in which to interpret data from the study of fine scale relationships.

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