Dynamics of total lipids and fatty acids during embryogenesis and larval development of Eurasian perch (Perca fluviatilis)

Total lipid and fatty acid compositions were determined during embryogenesis and larval development in Eurasian perch (Perca fluviatilis). During embryonic development, perch did not catabolize lipids and fatty acids as an energy source. However, during larval development, there was an exponential relationship between the decrease in total lipids and the duration of starving (r ²=0.9957) and feeding (r ²=1). The duration of the starving period (10 days post hatching) was shorter than the feeding period (35 days post hatching). In both starved and fed larvae, there is an apparent preference in utilization of polyunsaturated fatty acids followed by monounsaturated fatty acids. Saturated fatty acids were utilized by neither fed perch larvae nor by starved perch larvae. In starved larvae, palmitoleic 16:1(n-7) and oleic 18:1(n-9) acids were the preferentially monounsaturated fatty acids catabolized and their contribution as energy source from total fatty acids catabolized over the first week was 37.6%. In fed larvae, these 2 nutrients were also the most monounsaturated fatty acids utilized as energy source and possibly also as precursors for others monounsaturated fatty acids biosynthesis. During the same period and among (n-6) polyunsaturated fatty acids, starved perch utilized less linoleic 18:2(n-6) and arachidonic 20:4(n-6) acids than fed larvae despite the fact that the starved perch were in more unfavorable nutritional conditions. In the case of (n-3) fatty acids, starved larvae utilized more linolenic acid 18:3(n-3) and less eicosapentaenoic 20:5(n-3) acid and docosahexaenoic 22:6(n-3) acid than fed perch. Starved larvae probably spared 20:5(n-3) and 22:6(n-3) for physiological functions.