The brine shrimp, <i>Artemia salina</i>: a bottleneck in mariculture?

For many years the freshly hatched nauplii of the brine shrimp (Artemia salina) have been the most common live food used in mariculture of finfish and crustacea. The cysts from which A. salina nauplii hatch are harvested from unmanaged wild populations by primitive techniques and at only a few places in the world. As a result, good quality cysts are available only in limited quantities. With expansion of mariculture, demand for these cysts is exceeding the supply, which may lead to a serious bottle-neck in many aquaculture developments. A review of the studies on brine shrimp shows that the present critical situation can only be alleviated by revising the commercial exploitation of the cysts, as well as the practical use made of the latter in mariculture farms. In this respect it is suggested that: (i) The quality of commercially available cysts can be improved and their quantity increased by the application of new harvesting techniques. (ii) As salt lakes with Artemia are found all over the world (the collection at the State University of Ghent totals more than 60 different strains), comparative studies on the ecological characteristics and the nutritional value of different geographical races will lead to the selection of those that are best suited for aquacultural purposes. (iii) Hatching of the larvae, followed by their separation from the hatching debris can be optimized by the application of new and standardized techniques. This can lead to increased survival of larvae by at least 50% and a reduction of 90% in the equipment and labour involved. (iv) Biochemical analyses to determine nutrient value of the larvae indicate that freshly hatched Artemia nauplii should be offered to the predator as soon as possible after hatching. (v) High density culturing techniques for Artemia larvae have been developed that are fully automatic and economically feasible. By using air-water lift operated raceways, densities of 3000 shrimps per litre can be cultured from the first nauplius to the adult stage within 2 weeks on a diet of commercially available dried algae. (vi) The use of juvenile brine shrimp larvae of appropriate sizes instead of freshly hatched nauplii offers several nutritional and economical advantages in terms of utilization by fish and crustacean predators