Distribution and identification of the fatty acids from the coho salmon,Oncorhynchus kisutch (Walbaum)

To study the fatty acids of the coho salmon, entire fish were homogenized and the total lipids extracted with methanol-chloroform. The fish ranged in size from 75 to 85 mm total length and contained from 2.1%–6.9% lipid in the tissues. Methyl esters of the fatty acids were produced with anhydrous methanol and HCl. Qualitative identification of the fatty acid methyl esters was accomplished by gas-liquid chromatography. Thin layer silver nitrate-silicic acid plates were used to separate the component methyl esters according to the number of double bonds. Location of the ethylenic groups of the unsaturated fatty acid methyl esters was established by reductive ozonolysis and identification of the aldehydes and aldehyde-esters produced. The number of carbons in the unsaturated fatty acid methyl esters was determined by hydrogenation of each of the fractions. Fatty acids found in the highest concentrations were: 16∶0, 16∶1, 18∶0, 18∶1, 18∶4, and 22∶6. Fatty acids 16∶0, 18∶1, 18∶2, 20∶5, and 22∶6, differed markedly from concentrations found in tubificid worms, the exclusive diet of the fish during the experiment. Technical Paper No. 2059, Oregon Agricultural Experiment Station Work supported in part by research Grant No. EF105, U.S.P.H.S.