Photo credit:Gurgen Khanamirian (Armenia)
Review: Gurgen Khanamirianand Abdel Rahman El Gamal (Founder of the website)
The inserted picture was taken in an intensive rainbow trout freshwater farm located in Central Jutland (Denmark). Fish production in this given farm amounts 100-110 kg/m3. The following review provides some background information on the development of trout culture in Denmark.
Denmark has long been one of the world’s pioneers in the farming of trout whereas pond farming of rainbow trout (Oncorhynchus mykiss ) began to exist around the beginning of the 20th century In 1914 there was 140 trout farms operating in Denmark whose production was primarily for export..
Almost all Danish freshwater trout ponds are located in Jutland (the western part of Denmark) where most abundant flowing streams do exist.
Originally, trout culture in Jutland was practiced in earthen ponds with relatively simple practices using water diverted from a river, led through the ponds and released again into the same river. Not long ago, fish used to be fed minced fish till harvest of about 300-350 g average size.
The growth of trout farming industry has raised environmental concerns due to the disposal of farm effluent (faeces and unused food) in Danish streams causing significant conflicts with the wild fishery as well as other water uses.
Accordingly, gradual changes in the trout farming took place whether in the construction or in operation; concrete ponds have gradually replaced earthen ponds and farm effluents are strictly monitored to reduce the amount of nutrients returning to rivers.
Because most of the suitable freshwater areas (almost all in Jutland) are now in use, the traditional extensive systems are gradually replaced by intensive farming methods conditioned by the necessity to keep effluent discharge in compliance with the environmental regulations which include assigning maximum amount of fish that can be produced from each farm as well as the annual amount of feed which a farm can use and so the allowable effluents a farm can produce.
In order to cope with such strict environmental regulations, many of trout producers have to move towards cleaner practices such as the farms that use recirculation technology while the restricted feeding is widely spread among freshwater trout producers to improve the utilization of provided feed allowances and to reduce losses to the environment.
