Bio-physical drivers of bowhead whale distribution on the Alaskan Beaufort Shelf during a period of rapid environmental change - Shipboard CTD (Conductivity, Temperature, and Depth) August-September 2021

The region near Pt. Barrow has long been known as a place where bowhead whales congregate during their fall migration from the Canadian Arctic to the Bering Sea and are available for hunting by local coastal communities. Eleven years of fieldwork (2005-2015) from mid-August until early-mid September supported by the National Science Foundation (2 projects), Bureau of Ocean Energy Management (1 project), National Oceanographic Partnership Program (1 project), University of Alaska Fairbanks (UAF) Coastal Marine Institute, Woods Hole Oceanographic Institution Arctic Initiative, and the North Slope Borough Department of Wildlife Management showed that local wind conditions (krill trap) reliably produce dense aggregations of krill on the shelf to the northeast and east of Point Barrow that provides optimal feeding conditions for the bowhead whales (bowhead whale feeding hotspot). Summer-fall environmental conditions along the north coast of Alaska have been changing rapidly since 2015 and the bowhead whale presence near Pt. Barrow has become less reliable, with near absence of the whales in 2016 and 2109. Bowhead whale migration distributions on the Beaufort Shelf are impacted by availability of their plankton prey (krill, copepods) along their migration route, however there were few observations since 2015 to identify what was driving these changes. In response to this need, the Bureau of Ocean Energy Management (BOEM) supported “Bio-physical drivers of bowhead whale distribution on the Alaskan Beaufort Shelf during a period of rapid environmental change” sought to understand if environmental changes along the North Slope were modifying bowhead whale migration behavior and thus availability near Pt. Barrow. A combination of boat-based surveys of hydrography and plankton, short-term (weeks) and year-round moorings equipped with hydrographic sensors, current profilers, echosounders, and hydrophones deployed at key locations, and laboratory analyses were conducted. Boat surveys were done in August-September 2021-2024. This dataset contains water column profiles from CTD casts collected from the research vessel (R/V) Annika Marie or the R/V Ukpik in August-September 2021.