STRATIFICATION AND AGE-RELATED DIFFERENCES IN BLUBBER FATTY-ACIDS OF THE MALE HARBOR PORPOISE (PHOCOENA-PHOCOENA)

Fatty acid composition of blubber was determined at four body sites of 19 male harbour porpoises. A total of 65 fatty acids were quantified in each sample. The array of fatty acids contained in harbour porpoise blubber was similar to those found in other marine mammals. While che mical composition of total blubber was uniform over the body, with the exception of the caudal peduncle, vertical stratification was evident between the deep (inner) and superficial(outer) blubber layers. Fatty acids with chain lengths shorter than 18 carbons were present in sign ificantly greater amounts in the outer blubber layer, while the longer -chain unsaturated fatty acids were more prevalent in the inner layer. This distribution suggests that the inner blubber layer is more activ e metabolically than the outer layer in terms of lipid deposition and mobilization. The degree of stratification between the two layers appe ars to increase with age, indicating a predictable turnover in the blu bber layer of male porpoises. Harbour porpoise blubber contained high levels (2-27%) of isovaleric acid in the outer blubber layer, and thes e levels were positively correlated with age.