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Marine Ecology Progress Series

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MEPS 393:173-183 (2009)  -  DOI:

Tracing migratory movements of breeding North Pacific humpback whales using stable isotope analysis

Briana H. Witteveen1,3,*, Graham A. J. Worthy1,2, James D. Roth1

1University of Central Florida, Department of Biology, 4000 Central Florida Boulevard, Orlando, Florida 32816-2368, USA
2Hubbs-SeaWorld Research Institute, 6295 Sea Harbor Drive, Orlando, Florida 32821, USA
3Present address: University of Alaska Fairbanks, School of Fisheries and Ocean Sciences, 118 Trident Way, Kodiak, Alaska 99615, USA

ABSTRACT: North Pacific humpback whales Megaptera novaeangliae are migratory animals with a complex population structure, segregating into geographically distinct aggregations on high-latitude feeding grounds. Several feeding aggregations may converge on a common breeding ground for mating and calving. Understanding how feeding and breeding habitats are linked is critical to understanding humpback whale life history and addressing management and conservation efforts. In a continued effort to explore the population structure of North Pacific humpback whales through the analysis of stable carbon (δ13C) and nitrogen (δ15N), the present study extends on a previous study of feeding animals to describe migratory linkages to breeding grounds (Witteveen et al. 2009). Skin samples (n = 597) collected from 4 known breeding regions were analyzed for δ13C and δ15N. Breeding regions differed in both δ13C (F3,585 = 62.3, p < 0.001) and δ15N (F3,585 = 37.2, p < 0.001). Breeding values reflected the foraging locations for 46 ind. sampled on both habitats; the relationship between the breeding and feeding stable isotope ratios was significant and positive for both δ13C (F1,44 = 10.3, r2 = 0.19, p = 0.002) and δ15N (F1,44 = 40.9, r2 = 0.48, p < 0.001). Furthermore, individual breeding and feeding values did not differ for δ15N (t45 = 1.41, p = 0.17) or δ13C (t45 = –1.15, p = 0.26) in pairwise comparisons. We used δ13C and δ15N in a classification tree analysis to describe probable migratory linkages to 6 previously described feeding groups. Stable isotope ratios predicted regional patterns of movement, and assignments of breeding individuals to feeding grounds differed by 12% on average from photographic matching. Our results indicate this technique can be used to help understand the population structure and ecology of North Pacific humpback whale populations, especially when used in combination with other research techniques.

KEY WORDS: Classification tree analysis · Megaptera novaeangliae · Migration · Stable isotopes

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Cite this article as: Witteveen BH, Worthy GAJ, Roth JD (2009) Tracing migratory movements of breeding North Pacific humpback whales using stable isotope analysis. Mar Ecol Prog Ser 393:173-183.

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