Past, Present, and Future for Bowhead Whales (Balaena mysticetus) in Northwest Hudson Bay

Abstract

The bowhead whale (Balaena mysticetus) is the largest Arctic cetacean and the only baleen whale to live year-round in high-latitude waters. In this chapter we discuss the ecology and shifts in ecosystem structure and energy transfer among trophic levels due to changes in bowhead population size in the Hudson Bay region. Eastern Canadian Arctic bowheads comprise a single large, wide-ranging population that is shared between Canada and West Greenland, with considerable age- and sex-based segregation. In the Hudson Bay region important areas of aggregation include the spring nursery in northern Foxe Basin, summer locations in northwest Hudson Bay, and wintering habitat in Hudson Strait. Bowhead whales have been important for Inuit subsistence for millennia, and were commercially hunted in northwest Hudson Bay from 1860 to 1915. By the time whaling ended bowhead whales had been hunted to low numbers. However the bowhead population has grown in recent decades. We speculate on how rapid changes in northwest Hudson Bay population size, from pristine to depleted and now expanding, may have affected the marine ecosystem. First, bowhead removal would have resulted in a “freeing up” of zooplankton biomass, with potential cascading effects throughout the food web. Second, with population increases, more bowhead whales are now consuming more zooplankton, creating another ecosystem shift. Third, the region is rapidly losing sea ice due to warming likely resulting in future ecosystem changes. Population growth and warming are now occurring together necessitating a better understanding of bowhead ecology and ecosystem role to inform resource managers and policy makers. With better ecological data and explicit assumptions, detailed ecosystem models could be used to examine changes in ecosystem structure over time and into the future.