Page 25 - fish_farms_curriculum

Water is supplied to the canals from artesian geothermal wells at 32°C at a flow rate of 380

liters/s. Cold water from springs and streams is used to cool geothermal water to temperatures
between 27°C and 29°C, which is the best production temperature. The storage density of the

fish produced varies between 80 kg/m³ and 160 kg/m³. Annual production is usually three or

four times the carrying capacity. In addition to raising catfish, manufacturers also raise tilapia.
Their production is at the level of 227 tons and 45 tons, respectively. Rainbow trout and

sturgeon are grown in cold water on adjacent land. During the processing of these fish to be
put on the market, over 90 tons of waste is generated annually. To solve this waste disposal

problem, producers started breeding American alligators in 1994. Alligators feed on fish

waste and are harvested annually for their meat and skin. Giant freshwater shrimp (Macro
brachium rosenbergii) were bred from 1975 to 1988 at the Oregon Institute of Technology in

the United States. Researches were also carried out on trout culture and mosquito fish
(Gambuzia affinis) in this research area. These studies have shown that aquaculture and

tropical arthropods can be grown even in cold climates with low temperatures as low as -7°C,
when the water temperature is kept at an optimal level.

Picture 9. Alligator

Initially, two small outdoor ponds of 1.2 m depth were used before constructing the

cultivation ponds of 0.2 ha (1 ha = 10000 m²) each were built. A selected group of breeding
giant shrimp were housed in a small hatchery, where the larvae were hatched in artificial salt

water and housed until the post-larval stage. For the highest animal density, 900 cm² surface

area and 2 cm growth rates per month (twice that in tropical areas) were obtained. In order to
provide the optimum temperature (27°C to 30°C), the system in the supply pools is composed

of perforated distributor pipes, control valves and temperature control elements. With this
system, equal distribution of geothermal energy to all sides of the pools was ensured.

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