Fine‐scale spatial differences in humpback whale diet composition near Kodiak, Alaska

• Published in: Marine Mammal Science
• Main Authors: Wright, Dana L., Witteveen, Briana, Wynne, Kate, Horstmann‐Dehn, Larissa
• Other Authors: NOAA NMFS, NOAA Gulf Apex Predator-prey (GAP), Oscar Dyson Memorial Scholarship, UAF Robert Byrd foundation, Fairbanks Curling Club Scholarship, UAF IACUC
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 2016
• Subjects: Aquatic Science; Ecology, Evolution, Behavior and Systematics; Archipelago; Humpback Whale; Kodiak; Megaptera novaeangliae; Alaska
• Online Access: http://dx.doi.org/10.1111/mms.12311; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fmms.12311; https://onlinelibrary.wiley.com/doi/pdf/10.1111/mms.12311

Abstract On the North Pacific feeding grounds, humpback whales ( Megaptera novaeangliae ) are recovering from commercial whaling at a rapid rate (6.8%). The potential effect that this recovery will have on trophic dynamics involving these predators is currently unknown. To better elucidate complex trophic dynamics, variability in diet composition of apex predators on their respective feeding grounds needs to be understood. Thus, we explored the diet composition of two defined subaggregations of humpback whales of the Kodiak Archipelago population (“North,” “South”) using stable carbon (δ 13 C) and nitrogen (δ 15 N) isotope ratios of humpback whale skin and regional prey samples in Bayesian dietary mixing models. Humpback whales in the “North” region consumed proportionally more fish, dominated by capelin ( Mallotus villosus ), whereas, whales in the “South” region consumed predominantly krill. The difference in diet composition appears to reflect regional differences in prey availability. Thus, regional variability in diet composition by humpback whales may have disproportionate impacts on prey resources of sympatric predators depending on available prey biomass. As a result, we suggest fine‐scale studies of apex predator diets are needed to better model trophic dynamics with accuracy.