Fatty Acid Composition of Unfed Cod Larvae Gadus morhua L. and Cod Larvae Feeding on Natural Plankton in Large Enclosures

Three different groups of cod larvae Gadus morhua L ., feeding on natural plankton in two large enclosures, were analyzed for fatty acid composition through development. Unfed control groups and different size-fractions of plankton were also analyzed. Consistency in changes of fatty acid composition suggests three developmental periods during early larval development. The periods corresponded with dietary shifts in the larvae, but a metabolic origin for changes in certain fatty acids was also evident. In the first period, relative amounts of n-9 monounsaturates decreased, while n-3 polyunsaturates together with certain fatty acids abundant in the small-sized phytoplankton fraction increased. In the second and third periods, relative amounts of the longer n-3 PUFA decreased, while fatty acids of calanoid copepod origin occurred in one group. The consistency in changes of larval fatty acid profiles in cod suggests development in both lipid absorption and lipid metabolism during ontogenesis.