Abstract:Antarctic krill (Euphausia superba) is a rich resource of polyunsaturated fatty acids and proteins. Therefore the contents of the two nutritional components are the determining factors of the economic value of Antarctic krill. To help improve the efficiency of utilization of Antarctic krill, we employed the Soxhlet extraction method and selected the optimal solvent for lipid extraction from anhydrous ethanol, acetone, petroleum ether, hexane, ethyl acetate and cyclohexane. We also analyzed the seasonal variation in the levels of lipids and proteins, and investigated the effect of the body length on the nutritional contents of Antarctic krill. Samples were collected from the water nearby the South Georgia Islands between June and August 2013 and from the water nearby the South Shetland Islands between December 2013 and May 2014. It shows that anhydrous ethanol was the best extraction solvent examined for determining the lipid content of Antarctic krill. The contents of lipids and proteins of samples from the South Georgia Islands were (22.03±0.51)% and (64.52±0.16)% (in dry matter) respectively. The levels of both lipids and proteins of smaller individuals (<40 mm in total length) were higher than those of the larger ones (>40 mm, P<0.05). The lipid content of samples from the South Shetland Islands showed an increasing trend from early summer to late fall, the level raised from (19.83±0.04)% in December to the peak value (30.58±0.02)% in April, followed by a decline to (28.66±0.03)% in May. In contrast, the protein content was the highest in December (66.75±0.14)% and the lowest in April (58.02±0.23)%. There was a significant and negative correlation between the lipid content and the protein content (P=0.005). These results can be used directly to guide the arrangement of actual fishing operation of the krill fishery.
