The present paper dealt with the quadratic and linear regressions of compositional percentage of fatty acids on lipid content in the mackerel, Scomber japonicus, and the multiple linear regression of the fatty acid content on the season, body length and lipid content. The polar lipid differed from nonpolar and total lipids in the pattern of change in compositional percentage of the fatty caids with increase in lipid content.
In nonpolar and total lipids, the contents of all the fatty acids increased in accordance with increase in lipid content. The content of 16:0 acid in nonpolar lipid showed a larger proportional increase while those of 18:0, 20:3 and 22:6 acids in both nonpolar and total lipids showed increases smaller than the increase in lipid content. When the change in compositional percentage was related to the increase in lipid content, this resulted in an increase in 16:0 acid but decreases in the others.
In polar lipid, the contents of 22:6 and 20:3 acids decreased with increase in lipid content while those of other acids showed neither increase nor decrease. This resulted in a decrease in 22:6 acid and compensating increase in 16:0, 18:1 and 20:1 acids with incrase in lipid content when compositional percentage changes were related to increase in lipid content.