Preliminary Results on the Fatty Acid Composition of Freshwater Crayfish, Astacus astacus and Pacifastacus leniusculus, Held in Captivity

The fatty acid compositions of the tail muscle and hepatopancreas of captive noble crayfish Astacus astactus and of signal crayfish pacfastacus leniusculus were investigated. The major fatty acids in the tail muscle of A. astacus were 16:0. 18:ln-7 + 9, 20:4n–6 and 20:5n–3 and the fatty acid composition of hepatopancreas was principally 16:0, 18:In-7 + 9 and 20: ln-9+ 11. These animals had been fed marine fish (sprat and herring) for 2 mo. They were kept in a flowthrough system with gravity-fed fresh water from a nearby lake with a high concentration of calcium and pH above 8. The major fatty acids in the tail muscle of P. leniusculus were 16:0. 18:ln-7+9, 18:2n–6 and 20:5n–3, and in the hepatopancreas 16:0, 18:1n–7 + 9 and 18:2n–6. These animals had been fed mainly plant material (green peas, maize and alder leaves) in a different laboratory for a period of about 2 yr and kept in a flow-through system with ambient water of pH around 7. In A. astacus the total fatty acid content was nearly 13 times higher in the hepatopancreas than in the tail muscle, however, three fatty acids 18:0, 20:4n–6 and 20:Sn-3 were, respectively, 289, 403, and 320% more concentrated in the fatty acids of tail muscle than in the hepatopancreas. Total fatty acids of the hepatopancreas of male P. Ieniusculus was 42 times higher than in the tail muscle and was three times greater than in the hepatopancreas of A. astacus .