Design and operational characteristics of a Tilapia rearing system for temperate regions
Abstract
Typescript (photocopy).A small-scale spawning and rearing facility for the production of Tilapia aurea fingerlings was constructed in a polyethylene-covered greenhouse. Spawning and fry rearing during the winter extended the growing season by two months. Fish averaging 3.0 cm total length were stocked in ponds during April. Lights and small immersion heaters were used to regulate spawning conditions in 1,100 liter fiberglass tanks. T. aurea broodfish were stocked and allowed to spawn. The fry were subsequently collected and treated with synthetic testosterone producing only male fish. Fry hormone treatment was done in a small recirculating system to maintain temperatures above 20 C. After sex-reversal, fry were held indoors in tanks until outside water temperature stabilized at 20 C. The fish were then stocked into two 0.1 hectare ponds. Over a 66 day period, 59 broodfish spawned, resulting in 2,348 fingerlings being produced. After 191 days of pond culture, 2,130 fish weighing an average of 518 g were harvested. No fry were recovered from the ponds, indicating that the hormone-treatment was successful. Total construction and operating costs of the fingerling production system were used in a computer budget simulation model to estimate the profitability of the system. A small facility such as the one described and equipped for research purposes would produce fingerlings at an estimated unit cost of 0.27 per fingerling. A system that could produce 120,000 fingerlings over six months would reduce costs to $0.18 per fingerling. A telephone survey of tilapia producers in the United States provided information on current production methods and market problems. Assessing market demand and providing a steady source of fish to retailers appear essential to the establishment of a successful tilapia operationSimilar works
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