USING STABLE ISOTOPES TO ASSESS THE POPULATION STRUCTURE AND FEEDING ECOLOGY OF NORTH PACIFIC HUMPBACK WHALES (MEGAPTERA NOVAEANGLIAE)

• Other Authors: Witteveen, Briana (Author), Worthy, Graham (Committee Chair), University of Central Florida (Degree Grantor)
• Format: Text
• Language: English
• Published: University of Central Florida
• Subjects: stable isotopes; feeding ecology; migration; humpback whales; North Pacific; Pacific; baleen whale; Humpback Whale; Megaptera novaeangliae
• Online Access: http://purl.flvc.org/ucf/fd/CFE0002386

The North Pacific humpback whale (Megaptera novaeangliae) is a wide-ranging baleen whale species with a complex life history and population structure. As seasonal migrants, humpback whales are known to inhabit cooler, high-latitude waters when foraging and low-latitudes for mating and calving. Beyond this general migratory pattern, a number of demographic characteristics including, abundance, distribution, seasonal occurrence, and prey preferences remain unknown or poorly described. A complete understanding of humpback whale ecology is therefore lacking. Many methods used to explore these aspects of cetacean ecology are either prohibitively expensive or limited in the scope of what can be learned from their use. Fortunately, in recent years, the analysis of stable isotope ratios of animal tissues has proved a valuable and relatively inexpensive technique for providing information on trophic position, diet, and feeding origins of migratory populations. This study employed techniques in stable isotope ecology to increase knowledge of the population structure, migration routes, and foraging ecology of North Pacific humpback whales. Skin samples were collected from free-ranging humpback whales throughout all known feeding and breeding grounds and were analyzed for stable carbon (13C) and nitrogen (15N) isotope ratios. The population structure of humpback whales was first explored through geographic differences in stable isotope ratios. Stable isotope ratios varied significantly with location of sample collection. Based on this analysis, foraging animals were separated into six feeding groups. Classification tree analysis was then used to determine which isotopic variables could be used to predict group membership. Probable migratory linkages were then described by applying results of classification trees to 13C and 15N of animals sampled on breeding grounds. Strong migratory connections between the eastern-most foraging and breeding areas and the western-most areas were reflected in similarities of stable isotope ...