Characterization of Fatty Acids in Blubber and Thoracic Appendages of Pygmy and Dwarf Sperm Whales (Kogia breviceps and Kogia sima)
Goodson, Abby M.
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Pygmy sperm whales (Kogia breviceps) are the second-most commonly stranded cetaceans along the Southeast coast of the Unites States, yet very little is known about their basic biology. Blubber fatty acids and lipid class composition have not been fully described in this species, and may supply valuable baseline data that could provide insight to the health, diet, and metabolic processes of this species. Approximately half of the pygmy and dwarf sperm whales (Kogia sima) that strand along the southeastern U.S. coast suffer from a heart disease known as cardiomyopathy; the etiology of this disease in cetaceans remains unknown. Lipid content (gravimetrically), lipid class composition (TLC∼FID), and fatty acid composition of triacylglycerols and wax esters (GC/FID) were characterized in blubber samples from stranded pygmy and dwarf sperm whales with and without cardiomyopathy. A prominent visceral fat deposit located adjacent to the lung has also been consistently observed in K. breviceps during necropsy and where available, these appendages were also examined. K. breviceps blubber samples were lower in lipid (49.6 +/- 2.5%, mean +/- SEM) than K. sima (70.2 +/- 1.5%), and K. breviceps animals had higher wax ester content in blubber (92.6 +/- 2.3%) than K. sima (47.9 +/- 9.5%). Wax ester content increased with length in K. sima animals, and species differences could not be fully evaluated due to length differences between K. sima and K. breviceps used in the study. Thoracic appendages consisted of almost entirely wax esters. The most abundant blubber fatty acids were 18:1n∼9, 16:0, and 16:1n∼7 and these accounted for 62% of the total fatty acids in both species. Differences in fatty acid profiles were detected between the two species, as well as between internal and blubber lipids, but no differences were found between diseased and non-diseased animals. Fully understanding the biology of an animal is critical to its population viability and is necessary to ensure the presence of these species for future years.