The major problem area in the cultivation of marine fish is the culture of the early life stages and control of larval nutrition is a key element. The use of live food for hatchery culture of marine fish larvae is currently considered obligatory for successful culture. However, their use is costly, especially during recent years where global harvests of Artemia cysts have decreased sharply leading to a global shortage. To produce 10,000 snapper or barramundi juveniles (50 days old) past metamorphosis, 1.5 kg of Artemia cysts is needed. The production cost of Artemia nauplii is 10 cents / juvenile (Frankish, pers. Comm.), which includes Artemia cysts, enrichments, labor and running costs (e.g. heaters, air etc.). Currently, 1 kg of Artemia cysts cost $AU-400-500; however, it is now almost impossible to obtain them in Australia. Replacing even 50% of imported Artemia cysts may result in substantial cost savings leading to more efficient hatchery production and facilitating industry expansion.
The FRDC R&D plan for hatchery feeds (the outcome from the FRDC hatchery feeds workshop, Cairns, Qld.) put a high priority on R&D projects to find local solutions to overcome the ‘Artemia crisis’ and reduce dependence on imported Artemia cysts. More specifically, it emphasised three particular research needs: (1) to assess the potential of Australian Artemia strains; (2) to determine the effectiveness of currently available artificial diets for finfish larvae; and (3) to develop ‘local’ artificial diets and protocols for weaning and co-feeding of live and dry diets. The R&D priorities (FRDC plan) for Artemia and artificial diets are attached as Appendix 1.
Final report
This project was initiated based on recommendations and R&D priorities as identified at the First Hatchery Feeds Workshop (Cairns, QLD 1999). Several aspects were found to have high priority, such as: systems, Artemia availability and its nutritional quality, microdiets to reduce and/or replace reliance on Artemia, and feeding and weaning protocols. It was recognised that these areas were ‘bottle necks’ in the further development of marine aquaculture, especially with new species. These high priority aspects were addressed in this project, which exceeded its objectives. Its outcomes include, among others, products and systems that are already commercially available, and laying the foundation to commercialisation of at least two new products / organisms, i.e. brine shrimp Artemia culture in Australia and larvae microdiets.
The development of the larvae rearing system and the associated live food enrichment system involved innovative solutions in terms of automated systems, dosing and feed delivery systems, and filtration. These systems allow better control and save time and money. Some parts of the systems have already been adopted by industry. For example, the tank design is currently being evaluated at the M.G. Kailis, Exmouth hatchery. The innovative microdiet feeding system is currently being installed at the Tasmanian Aquaculture and Fisheries Institute in their larvae tanks. The larvae rearing system and/or other specific systems can benefit any R&D centre involved in marine larvae rearing as well as commercial hatcheries. It is proposed that these systems will be progressed as a commercial product, depending on demand.
