Fatty acid composition of the blubber in white whales (Delphinapterus leucas)

Fatty acid (FA) composition of the blubber in free-ranging white whales (De lphinapterus leucas) from Svalbard's waters was determined and compared wit h the fatty acid composition of potential prey species in an attempt to ass ess diet. This methodology is based on the common assumption that unique ar rays of FAs found within groups of organisms are transferred, largely unalt ered, up marine food chains and thus may be useful for assessment of diet c omposition. Complete-column blubber biopsies were sampled from white whales (n = 7) during the summers of 1996 and 1997. All captured animals were adu lt males. FAs were extracted from 2-4 replicates taken from an area about 1 0 cm in front of the mid-dorsal ridge. FA data from a total of 12 potential prey species from the Svalbard area were compared to the white-whale blubb er samples. Twenty-two FAs were consistently found in relative amounts > 0. 5% of the total FA composition in white whales. These FAs accounted for 94- 96% of the total FAs present. The blubber was composed almost entirely of t riacylglycerols. The major saturated FAs were 14:0 and 16:0; 16:1(n-7), 18: 1(n-9) and 20:1(n-9) were the major monounsaturated FAs and 20:5(n-3) and 2 2:6(n-3) were the major polyunsaturated FAs. Sixteen of the 22 FAs consiste ntly found in the white-whale blubber were also found in considerable amoun ts (>0.5% of total FGs) in most of the potential species. Principal Compone nt Analysis run on these 16 FAs suggests that polar cod (Boreogadus saida) had the most similar FA composition to the white-whale blubber, followed by capelin (Mallotus villosus), the copepod Calanus hyperboreus and the shrim p Pandalus borealis.