Use of Beaufort Sea as feeding habitat by bowhead whales (Balaena mysticetus) as indicated by stable isotope ratios

Abstract

The feeding habitats of the Western Arctic bowhead whales (Balaena mysticetus) during summer are generally known, but the precise amounts of food consumed from the eastern Beaufort Sea (EBS) are not known. [Alpha]13C and [alpha]15N ratios in whale tissues were used to estimate the amounts of food required from EBS. The feeding strategies of adults and subadults were also compared. For all whales, the [alpha]13C values in muscle sampled in fall were not significantly different from those in the muscle sampled in spring, indicating most food of adults and subadults comes from the Bering/Chukchi seas. The ¹³C data from baleen showed, however, that EBS may be a significant feeding area for subadults. [alpha]15N values are significantly different between fall and spring muscle in subadults, suggesting a shift to different prey and/or nutritional stress during winter followed by feeding in EBS in summer.