MEPS 461:283-291 (2012)  -  DOI: https://doi.org/10.3354/meps09769

ABSTRACT: This study was performed to evaluate the stability of the fatty acid (FA) composition of blubber from Baltic grey seals Halichoerus grypus archived at −25°C in the Swedish Environmental Specimen Bank (SESB). Possible alterations of FA compositions with storage time and temperature were evaluated. Blubber from 5 seals was kept at +2°C and at −20°C and sampled for up to 6 mo and 33 mo, respectively. Furthermore, FA profile stability was evaluated in blubber stored in the SESB for 4 and 6 yr. This was done by re-sampling and re-analyzing blubber samples from SESB. In both parts of the study, a principal component analysis was performed on 48 FAs comprising 98 to 99% of the total FAs in blubber of Baltic grey seals. We found no indication of a critically altered FA composition, neither in blubber stored at +2°C for 6 mo nor in blubber stored at −20°C for 33 mo. The re-analysis of samples stored in SESB for ~4 to 6 yr only differed for a few FAs in some samples. The most remarkable differences were a slight increase in some long-chain unsaturated FAs (18:2n-6, 20:3n-3, 20:4n-3, 22:4n-3). As an increase in long-chain polyunsaturated FAs due to storage is highly unlikely, we believe that this is probably more due to the sampling technique than to a critically altered FA composition due to storage. Our results suggest that archived seal blubber may be safely used in retrospective analyses of diet using an FA signature analysis technique.

KEY WORDS: Fatty acid composition · Long-term storage · Blubber · Grey seal · Baltic Sea