have been introduced to the world cyst market with sites such as Karabogaz-Gol in Turkmenistan, a vast hypersaline bay of the Caspian Sea, but also from a plethora of small or medium-sized lakes occurring within an area stretching from the Kurgan area in Southwest Siberia, over the Altai area (South Siberia) and Kazakhstan, eastwards into continental and coastal China (Bossier et al. 2004).
It remains difficult to provide good predictions for the future because less information is available on the ecology of these new Artemia habitats. However, even if the long-term stability of the cyst supply remains uncertain, the current diversification of sources will at least limit the risks of sudden shortages due to environmental changes.
The range of applications for cysts originating from these alternative sources is mostly analogous to the GSL strain, which is unofficially considered as a 'standard' in aquaculture practices. However, since these new species are dominated by a variety of parthenogenetic populations they often display characteristics that deviate markedly from GSL cysts, which affect suppliers and customers. These characteristics include diapause features, chorion colour, cyst and naupliar biometrics, nutritional (HUFA) profile, buoyancy, decapsulation requirement and behaviour, hatching percentage and hatching rate, separation of instar I nauplii in hatching vessel, enrichment requirements, etc. This applies also to several Artemia sources with only local or regional commercial importance, such as A. sinica from several lakes in continental China and adjacent territories, and A. urmi-ana from Lake Urmia, Iran.
In addition, smaller cyst quantities (1-201 each) of mostly good hatching quality are expected to be provided on a more continuous basis from man-managed ponds and saltworks worldwide (Brazil: Camara 1996; Vietnam:
Baert et al. 1997; Indonesia: E. Kontara, pers. comm. 1995; Chile, Colombia, Eritrea, India, Madagascar, Pakistan, Peru, Thailand: Triantaphyllidis etal. (1998) and various personal communications). These small-scale cyst production sites, although technically very successful in several countries in Southeast Asia and Latin America (Sorgeloos 1987), are not expected to contribute significantly to global cyst supplies. Nevertheless, they provide interesting opportunities for local commercial developments, especially in developing countries with import restrictions. In these situations, local cyst availability is an important asset in the development of viable hatcheries.
The latter developments, if well followed-up, may provide several thousands of metric tons of harvestable cysts on an annual basis (Lavens & Sorgeloos 1998). However, it is necessary to stress again that the lack of ecological knowledge for the natural lakes implies that no long-term predictions on productivity can be made. Furthermore, their operation will be cost/market driven, and high productions at the GSL will automatically result in a drop of interest and profitability elsewhere. Also, there are often differences in cysts from alternative locations from the 'classic' GSL product which require attention when applying them in crustacean hatcheries. A few examples may illustrate this:
• Deactivation of the dormancy status of Central Asian cysts seems to be difficult, which often limits their hatching performance
• The classical techniques for cyst decapsulation are not applicable with cysts from Central Asia without decreasing their viability, unless some modifications to the protocol are implemented.
• Most of the parthenogenetic strains from Asia have a large cyst size.
• Little information is available on the nutritional quality of these sources.
Hatchery operators need to have precise information on the origin and characteristics of the cysts which they purchase. It remains therefore desirable for Artemia suppliers to provide this information on the cyst products they market, and that no blends ofdifferent sources should be processed as has happened in the past. Nowadays it is even possible to identify the origin of commercial cyst products by means of a DNA-fingerprinting technique fine-tuned for application with Artemia (Sun et al. 1999, Bossier et al. 2004).
The question of the future demand for cysts remains. Again it is difficult to assess annual requirements because a number of factors may interfere. It is difficult to predict the increase in numbers of fry produced by fish, freshwater prawn and marine shrimp hatcheries. Generally, it is expected that hatchery production of marine fish worldwide will further increase (Sorgeloos & Leger 1992), implying a
higher need for cysts. Currently, the biggest demand is for penaeidshrimp hatcheries (>80%). The operation ofthese hatcheries depends in the first place on the requirements of grow-out farms for juveniles. Although the high market prices for shrimp encourage enthusiasm for the expansion of the shrimp business, production increases may not be at the same pace as in the past. They may be limited because of new policies promoting responsible aquaculture, which involve lower stocking densities and less land converted into new ponds. Also disease outbreaks may limit farm operation in certain areas. On the other hand, cyst shortages encourage the application of modified feeding strategies during the hatchery cycle, reducing the quantities of Artemia required.
Artificial diets will certainly gain in popularity in the near future because they reduce the problems and risks involved in the production of live food. Quite a few products are already commercially available for some aquatic species, but their nutritional composition, digestibility and physical performance, especially regarding suspension in the water column and leaching, need to be further optimised before they can completely replace live food in freshwater prawn hatcheries. The application of micro-particulate diets may also depend on the goal which each hatchery seeks to achieve, i.e. the production of high numbers of PL (high densities and survival rates) or the production of high-quality fry (strong, resistant to stress and diseases). The use of formulated diets will be easier in the first case. In any case, it is the cost-effectiveness of the different feeding strategies that will determine the preferential application of inert feed diets or live food organisms. It is likely that this may differ considerably from region to region, and between industrial and backyard hatcheries.
Was this article helpful?
Lets start by identifying what exactly certain boats are. Sometimes the terminology can get lost on beginners, so well look at some of the most common boats and what theyre called. These boats are exactly what the name implies. They are meant to be used for fishing. Most fishing boats are powered by outboard motors, and many also have a trolling motor mounted on the bow. Bass boats can be made of aluminium or fibreglass.