• Гідрологія і Гідрометрія
• Господарське право
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• Економіка природокористування
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• Предмет Політологія
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• Технічні засоби організації дорожнього руху
• Товарознавство продовольчих товарів

Maximum load

The maximum load of organisms that can be cultured in a raceway system depends on the species, and particularly on the size of the species. For trout, stocking rates of 30 to 50 kg/m³ are normal at the end of a rearing cycle, while for marine species, such as sea-bass and sea-bream, the achievable load is lower, between 15 and 20 kg/m³. The total volume required for a raceway is calculated by dividing the total amount of fish in kg by the desired stocking rate in kg per m³.

Feed

In most raceway aquaculture food needs to be supplied. The composition of the food, and the amount and time of feeding needs to be adjusted to the specific species. This can be ptimized to reduce costs and minimize the amount of waste.

Waste water

The treatment of waste water issuing from raceway farms is a major concern. Fish fecal matter and uneaten feed are typically the major elements of solid waste produced in raceway aquaculture farms. These can adversely impact the environment in the receiving water body. Of particular environmental concern is the waste product phosphorus. Excessive discharge of phosphorus to receiving waters can result in eutrophication. For example, in Korea poor waste treatments in trout farms resulted in reservoirs and rivers developing red tides, which caused wider social problems.

Because raceway aquaculture operations discharge large volumes of water, the concentration of discharged solids is low. This means it is not easy to treat and implement practical, cost effective treatments. Technologies for the removal of solids include microscreens, dual-drain tanks, swirl separators, plate separators, baffles, media filters, air flotation, foam fractionation, chemical flocculation, and constructed wetlands. But because of the impracticality and / or high costs of these methods, most of them are not applicable for commercial aquaculture. As a consequence, sedimentation (settling) is still the most widely applied and cost effective technology. From 1999, regulations in South Korean require that all raceway farms provide waste water treatment facilities covering at least 20% of the farmed area to prevent pollution of the freshwater environment.

Appendix

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