Freshwater crayfish farming technology in the 1990s: a European and global perspective

This paper aims to describe the state of crayfish farming technology in the USA, Australia and Europe, and to discuss some of the prerequisites for this industry. Data from Europe are partly based on replies from a questionnaire sent out to scientists in all European countries. For other parts of the world, the crayfish literature has been reviewed and data from the August 2000 meeting of the International Association of Astacology are also included. Issues addressed in this review are cultivated species, production and productivity figures, production technique with regard to enclosures, reproduction and feed items, disease problems, predators, pond vegetation and water quality. Fewer than a dozen crayfish species are cultivated. The most attractive ones for culture and stocking in natural waters have been transferred to more than one continent. Pond rearing techniques predominate in all countries, and the technology required to achieve the spawning and rearing of juveniles is relatively simple. Pieces of fish, carrots and potatoes are frequent supplementary feed items; plants, cereals, pieces of meat, zooplankton and pellets are also common. Diseases are not usually a major concern, except in Europe where the American plague fungus, Aphanomyces astaci, has eradicated many European crayfish populations. Predators identified as common include insects and amphibians, as well as fishes, birds and mammals. Many water macrophytes are common in crayfish farms. These may either serve a useful function or cause problems for the crayfish farmer. Water temperature is the crucial factor for crayfish production. Water parameters such as pH and certain inorganic ion concentrations may also be of concern. Acidic waters that occur in some areas are generally detrimental to crayfish. The total yield from crayfish production from farming and fishery is in the order of 120 000–150 000 tonnes, more than four times the quantity given by FAO statistics. The largest crayfish producer is the Peoples’ Republic of China, followed by the USA (70 000 and 50 000 tonnes in 1999, respectively). Of the quantity produced in the USA in 1999, about 35 000 tonnes was farmed. The yield in Europe was about 4500 tonnes in 1994, and of this quantity only 160 tonnes came from aquaculture. There are no official statistics for crayfish fishery production in Australia, but about 400 tonnes came from aquaculture in 1999.     

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 .