The biochemical composition of krill, Euphausia superba Dana, from South Georgia

Abstract

Krill, Euphausia superba Dana, sampled from waters around South Georgia in 1978 contained 10–11% protein, 2–6% lipid, 0.3–0.6% carbohydrate, 2% chitin, and 3–4% mineral ash (all mean values, % fresh weight). Lipid content varied greatly with sexual maturity: males contained 2–4% lipid, immature animals 4% (both increasing to 5–6% later in the season) and mature females 5–6% (although some contained as much as 9%). Gravid females lost ≈60% of their lipid at spawning, and a biochemical estimate of fecundity gave values in the range 7000 to 15 000. The major lipid classes were phospholipid, triacylglyceropl, and free sterol, and there was 1–2% wax ester. The mean pigment content was 21.5 μg/g fresh weight. Triacylglycerol fatty acids were low in polyenoic acids and contained up to 4% phytanic acid; compositions were variable and showed the probable influence of dietary input. Phospholipids were rich in polyenoic acids, especially 20 : 5 ω3 and 22 : 6 ω3, and usually had 18 : 1 ω7 > 18 : 1 ω9. Ovarian triacylglycerol contained almost no polyenoic acids, but ovarian phospholipid was fairly unsaturated. These results are discussed in relation to the Antarctic environment, and compared with the results of previous work on caridean decapods.