Describing the diet of cetaceans is difficult because much of their foraging behavior and feeding occurs at depths where it cannot be directly observed. Our recent research efforts have focused on examining tissue chemical tracers, such as persistent organic pollutants, fatty acids and stable isotopes, measured in non-lethally obtained biopsy samples of free-ranging whales and dolphins, including Southern Resident killer whales, because these chemicals and isotopes are accumulated from their diet. Chemical tracer data combined with photo-identification catalogs, genetics information and other foraging behavior data provide a more complete picture of the likely prey preferences and primary foraging habitats of these marine predators.
This research theme supports the Title IV of the Marine Mammal Protection Act.
Heran, D.P., Burrows, D.G., Wade, P.R., Durban, J.W., LeDuc, R.G., Matkin, C.O., Krahn, M.M., 2005. Feeding ecology of eastern North Pacific killer whales from fatty acid, stable isotope, and organochlorine analyses of blubber biopsies. Marine Ecology Progress Series 302, 275-291.
Krahn, M.M., Hanson, M.B., Baird, R.W., Boyer, R.H., Burrows, D.G., Emmons, C.K., Ford, J.K.B., Jones, L.L., Noren, D.P., Ross, P.S., Schorr, G.S., Collier, T.K., 2007a. Persistent organic pollutants and stable isotopes in biopsy samples (2004/2006) from Southern Resident killer whales. Marine Pollution Bulletin 54, 1903-1911.
Krahn, M.M., Herman, D.P., Matkin, C.O., Durban, J.W., Barrett-Lennard, L., Burrows, D.G., Dahlheim, M.E., Black, N., LeDuc, R.G., Wade, P.R., 2007b. Use of chemical tracers in assessing the diet and foraging regions of eastern North Pacific killer whales. Marine Environmental Research 63, 91-114.
Ylitalo, G.M., Myers, M., Stewart, B.S., Yochem, P.K., Braun, R., Kashinsky, L., Boyd, D., Antonelis, G.A., Atkinson, S., Aguirre, A.A., Krahn, M.M., 2008. Organochlorine contaminants in endangered Hawaiian monk seals from four subpopulations in the Northwestern Hawaiian Islands. Marine Pollution Bulletin 56, 231-244.