Fatty acids play an important role in the biology of marine
fish. Polyunsaturated fatty acids such as DHA, EPA, and ARA are involved in the
regulation of membrane fluidity, nervous tissue development, sensory behavior,
and the synthesis of bioactive substances. Fatty acids also serve as a metabolic
source of energy. Information such as fatty acid content and fatty acid
composition is useful as an index that quantitatively or qualitatively
indicates the nutritional status of marine fish.
Figure: Fatty acid
analysis conducted with the muscles of larvae (above).
Approximately 50 types of fatty acids (including ARA, EPA, and
DHA) were quantitatively analyzed by gas chromatography.
EPA and DHA amounts included in natural Thunnus orientalis larvae (fatty acid composition)
The fish oil analysis team routinely analyzes over 500 samples of fatty
acids every year. Recently, we have succeeded in analyzing trace amounts of
fatty acids contained in one larva. By the method of gas
chromatography, we were able to analyze fatty acids in the muscle of
larvae with a length of around 3 mm. This new method will be a powerful tool
for investigating the growth and survival of wild larvae in the future.
Figure: Plots of EPA and DHA
proportions (mol% of total fatty acids) vs. standard lengths of Thunnus orientalis larvae.
The fatty acid analysis
revealed that the EPA content differed according to the sampling area (the Nansei
Islands with high water temperature vs. Sea of Japan with low water