Differences in the fatty acid compositions of blubber fats from northwestern Atlantic finwhales ( Balaenoptera physalus) and harp seals ( Pagophilus groenlandica)

Abstract

1. 1. Oil extracted from the blubber of one individual finwhale, and three commercial finwhale oils, have been compared with three commercial harp seal oils for details of fatty acid composition. 2. 2. The saturated acids showed no significant systematic differences in composition, but the proportion in whale oil was higher than in seal oils. 3. 3. The monoethylenic acids confirmed that 16:1 > 16:0 is typical of seal blubber; details of isomers showed that the 16:1 ω7 is extended to 18:1 ω7 and 20:1 ω7, and suggested that 18:1 ω9 is extended to 20:1 ω9. 4. 4. It is proposed that the seals, but not the whales, degrade a substantial part of ingested fatty acids to resynthesize 16:1. 5. 5. This hypothesis is examined from the viewpoint of the differing proportions of 22:1 to other monoethylenic fatty acids, and of diverse polyunsaturated fatty acids, in whale and seal fats. Comparisons are also made in terms of dietary fat sources and physiological factors.