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- Title
Stable isotope analysis reveals that humpback whales (Megaptera novaeangliae) primarily consume capelin (Mallotus villosus) in coastal Newfoundland, Canada.
- Authors
Johnson, Kelsey F.; Davoren, Gail K.
- Abstract
On the Newfoundland (Canada) foraging ground, humpback whales (Megaptera novaeangliae (Borowski, 1781)) are found associated with a dominant forage fish species, capelin (Mallotus villosus (Müller, 1776)), that experienced a population collapse in the early 1990s and has not recovered. Our primary goal was to reconstruct dietary proportions of humpback whales on their summer foraging grounds off the northeast coast of Newfoundland during July–August 2016 and 2017 using a Bayesian stable isotope mixing model (MixSiar). Modelled dietary proportions were similar in both years, with capelin comprising ∼90% of the diet. However, both δ13C and δ15N in humpback whale skin differed significantly between years, resulting in minimal isotopic niche overlap (9%). Lipid-extracted and nonlipid-extracted skin samples were used to develop a lipid normalization equation: Δ13C = –3.184 + 1.011(C:N). Overall, findings suggest that capelin is the primary prey type of humpback whales in coastal Newfoundland, despite the continued collapsed state of the capelin population. Findings also reiterate that dietary reconstruction from stable isotope analysis of cetacean skin can be misinterpreted without concurrently sampled isotopic ratios of potential prey types.
- Subjects
NEWFOUNDLAND &; Labrador; HUMPBACK whale; STABLE isotope analysis; FORAGE fishes; STABLE isotopes; CETACEA
- Publication
Canadian Journal of Zoology, 2021, Vol 99, Issue 7, p564
- ISSN
0008-4301
- Publication type
Article
- DOI
10.1139/cjz-2020-0257