Seasonal Variations Of Lipid And Protein Content Of Antarctic Krill(Euphausia Superba)

The abundant Antarctic krill(Euphausia superba) is the largest potential fishery resources known in the world, it is also a key species in the South Ocean ecosystem. The latest estimation shows the krill has an amount of between 0.65 to 1 billion tons. It is rich in nutritional value and has he characteristics of low lipid, high protein and so on. Oil products rich in polyunsaturated fatty acids and protein products used as raw food materials are the two main categories of Antarctic krill products. Changes in lipid and protein content of the animal will have direct impact on the economy of Antarctic krill fishery.Based on materials from the “Commission for the Conservation of Antarctic Marine Living Resource(CCAMLR)” and relevant published literatures, the actual fishing catch was lower compared to the lowest limitation. The resources of krill is still in the stage of un-fully development, so it has large protential untilization and development. Our country engaged in the research of antarctic krill as an important aspect of investigation since China has came into Antarctica in 1984. Today, China has establish the project of utilizing and exploiting resources of krill, and makes it as one of the ten fisheries development projects in the 21 th century. The pressure of current situation that the lacks offshore fishery resources is reduced by exploiting of Antarctic krill. Meanwhile it can promote the development of marine fisheries, and maintain the rights and interests of in Antarctica.With the development of the science and technology, the processing mode of Antarctic krill of our country has changed.Playing the potential value of raw materials,pursuing higher value-added of produ cts and realizing comprehensive explitation and utilization of resources are the primary i ssues that our Antarctic krill industry facing. For the purpose of providing reference for efficient extraction of krill oil with higher nutrition and higher added value as well as the comprehensive utilization of the Antarctic krill resources, the Soxhlet extraction method with anhydrous ethanol, acetone, petroleum ether, hexane, ethyl acetate and cyclohexane as extraction reagent was adopted to determine the optimal solvent for lipid extraction. Seasonal variation in the levels of lipid and protein content and its relationship with body length of Antarctic krill was analyzed based on the samples collected from South Georgia Islands waters from June to August 2013 and South Shetland Islands waters from December 2013 to May 2014. The result showed that :(1)anhydrous ethanol was the optimal extraction solvent to determine the lipid content of Antarctic krill.(2) For samples collected in waters adjacent to South Georgia Islands from June to August, the lipid and protein content(dry mass) were(22.03±0.51)% and(64.52±0.16)%, respectively; both lipid content and protein content of the specimens less than 40 mm in total length were higher than that larger than 40 mm(P<0.05).(3) For samples collected from waters adjacent to South Shetland Islands, lipid content of Antarctic krill showed an increasing trend from early summer to late fall, from(19.83±0.04)% in December to reach the highest value of(30.58±0.02)% in April, and then dropped to(28.66±0.03)% in May. In contrast, protein content was highest in December, lowest in April, the corresponding values were(66.75±0.14) % and(58.02±0.23)%, respectively.(4)A significant negative correlation( P=0.005) was observed between lipid content and protein content. These results could be proper guidance for the arrangement of the end products as well as the krill fishery.