Modeling the diet of humpback whales: An approach using stable carbon and nitrogen isotopes in a Bayesian mixing model

    Authors

    B. H. Witteveen; G. A. J. Worthy; R. J. Foy;K. M. Wynne

    Comments

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    Abbreviated Journal Title

    Mar. Mamm. Sci.

    Keywords

    humpback whale; Megaptera novaeangliae; Bayesian; dietary mixing model; d13C; d15N; stable isotopes; feeding ecology; FATTY-ACID SIGNATURES; MEGAPTERA-NOVAEANGLIAE; FOOD WEB; DELTA-C-13; ECOLOGY; FRACTIONATION; DELTA-N-15; ALASKA; PREY; TURNOVER; Marine & Freshwater Biology; Zoology

    Abstract

    Humpback whales are considered generalist predators, feeding on schooling fish, and zooplankton, but variability likely exists among regional feeding aggregations. We explored the diet of one feeding aggregation of humpback whales near Kodiak Island, Alaska, through analysis of the stable carbon (d13C) and nitrogen (d15N) isotope ratios of their skin and regional prey sources. Humpback whales were sampled during the summer feeding season over 3 yr (n= 93; 20042006). Prey samples were collected from the same region during trawl surveys conducted between 2003 and 2005. Isotope values of humpback whale skin and prey were entered into a Bayesian dietary mixing model to estimate feasible contributions of prey to humpback diets. Diet results indicated that humpbacks feed heavily on euphausiids, but also consume juvenile walleye pollock, capelin, and Pacific sand lance. The diet of humpback whales in 2004 was the most diverse, while diets in 2005 and 2006 showed a higher proportion of euphausiids. Our results reveal annual differences in humpback diets from the Kodiak region due to either individual prey preferences or prey availability. Application of a Bayesian mixing model to stable isotope analysis improves description of regional diets and comparison of these diets to resource availability and quality.

    Journal Title

    Marine Mammal Science

    Volume

    28

    Issue/Number

    3

    Publication Date

    1-1-2012

    Document Type

    Article

    Language

    English

    First Page

    E233

    Last Page

    E250

    WOS Identifier

    WOS:000305963100002

    ISSN

    0824-0469

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