Lipid and Astaxanthin Contents and Biochemical Post-Harvest Stability in Calanus finmarchicus

Calanus finmarchicus is the dominant zooplankton species in the North Atlantic. This zooplankton is also of interest for commercial harvesting due to its high abundance and biochemical contents. In the present study copepodite stage V of C. finmarchicus was sampled at different depths from January to June through 2009, 2010 and 2011 in the Trondheimsfjord (63°29'N 10°18'E). The fatty acid compositions of individual copepods and of the seston were analyzed. It was found that the fatty acid profile of the copepods was well related to the fatty acid profile of its potential food. The sampled C. finmarchicus contained 42% n-3 polyunsaturated fatty acids of total fatty acids (March-May). This study indicates that the onset of vertical migration of stage V, which was observed in May, has a strong link to the production of phytoplankton and the lipid accumulation in C. finmarchicus. The content of the fatty acids 14:0 and 16:0 in the specimens did not increase from February to May in surface waters. This indicates that these fatty acids in the diet were used as precursors for biosynthesis of the fatty acids 20:1 n-9 and 22:1 n-11, and fatty alcohols. A possible harvesting season of C. finmarchicus could be when the species is abundant in surface waters; the content of n-3 fatty acids will vary trough this season. The peak abundance of C. finmarchicus in the spring varied substantially between the years studied.