Abstract

Essential omega-3 (n-3) and omega-6 (n-6) long chain polyunsaturated fatty acids (PUFAs) are found in plants, nuts, vegetable oils, fish and marine animals. In animals and humans dietary PUFAs have protective effects against inflammatory conditions, neurocognitive disorders, and cardiovascular disease. Historically, fatty acids have been analyzed in the blubber of wild marine mammals to aid determination of trophic feeding levels in order to approximate prey type and feeding strategy. This study compared the n-3 and n-6 PUFA levels found in RBC membranes (which reflect the PUFA content of most major tissues) from wild Alaskan belugas with seasonally varying dietary habits with managed belugas fed a controlled diet of herring (Clupea harengus) and capelin (Mallotus villosus). Dietary fatty acid signatures varied between wild and managed belugas with 20- and 22-carbon monounsaturated fatty acids, which are characteristic of herring and capelin, linked to a copepod based food web, were higher in managed animals, while 20:4n-6 (arachidonic acid; AA) was higher wild belugas. High levels of AA have been observed in epibenthic invertebrates which suggest a pelagic link to food web. 20:5n-3 (eicosapentaenoic acid, EPA) was lower in wild belugas, whereas the other marine n-3 PUFA, 22:6n-3 (docosahexaenoic acid, DHA) was similar between groups. The Omega-3 index (RBC EPA+DHA, risk factor for cardiovascular disease in humans) was lower in wild belugas compared to managed belugas. Although blubber fatty acid patterns were not determined in this study, the use of RBC fatty acid patterns may be more useful tool for exploring dietary differences between wild and managed belugas and may therefore help in evaluating prey item diversity between beluga populations and PUFA-related health indices.

Acknowledgements

The research conducted on wild belugas was authorized under NOAA permit # 14245-04.

* Presenting author