Agri Kultuur September 2014 - Page 34

Article and photos by Henk Stander Animal husbandry depends on meeting the food and environmental requirements of the species concerned in a protected environment in order to realize enhanced survival and growth compared with that which would be obtained by harvesting from the wild. I n Recirculating Aquaculture Systems the water flows from a tank (s) to a treatment process and then is returned to the tank, hence the term recirculated or recirculating aquaculture systems. Recirculating or closed water systems continue to be used primarily for experimental work and for the rearing of larval organisms in commercial and research facilities, though increasingly; profitable commercial applications are being demonstrated. There is a great deal of interest in recirculation aquaculture production systems both in South Africa and worldwide. Most fish grown in Broodstock Tanks ponds, floating cages, or raceways can be reared in commercial scale recirculation systems, but economic feasibility of doing so is not certain. Recirculation systems are generally expensive to build and require a lot of energy to run which increases production cost. Environmental Conditions: The climate in South Africa ranges from desert and semi-desert in the north west of the country to subtropical on the eastern coastline. Temperatures are also quite extreme between summer and winter, it is getting quite cold (-5 to 10 degrees Celsius) in winter (MayAugust) at night and it is pleasantly Airlift System warm and sunny in spring and autumn, and often hot in summer (November to March) with frequent rains to cool things down. The day temperatures in summer are normally averaging between 25 to 35 degrees Celsius. The African continent is particularly vulnerable to climate change. In fact, with 80% of the African population dependent on agriculture for their livelihoods, it could cost as much as US$ 50 billion a year for Africa to adapt to the effects of climate change. Moreover, climate change could also mean a 50% decline in jobs related to fisheries. Drum filter