While several species of trout are farmed in Canada, rainbow trout (Oncorhynchus mykiss) is the species of choice.
Where they’re farmed…
While Ontario is the largest trout producer in Canada, trout farms can be found in all ten Canadian provinces. In 2006, Canadian trout farmers produced over 5,000 tonnes of high quality trout valued at over $21 million.
How they’re farmed…
To produce the highest quality farmed trout, the very best adult female trout are selected each year as breeding stock. Each female produces about 2000 eggs per kg of body weight; these eggs are fertilized and incubated in the temperature-controlled tanks of a freshwater hatchery.
Once they hatch, the baby trout are typically nurtured in circular tanks and cement raceways at the hatchery until they reach ~8-10 cm in length. Upon reaching this size, most young trout are moved to larger indoor or outdoor tanks. To ensure good fish health, the water in these tanks is cleaned and recycled on a continuous basis. Some trout are also raised in net-cages suspended in ‘largewater’ lakes. For the well-being of both the fish and the surrounding environment, the net-cages are located offshore in deep, pristine waters removed from other industrial and recreational users. In both the tank and net-cage production systems, dissolved oxygen and other water quality parameters are monitored to ensure optimal health of the fish. Depending upon the type of production system used, the young trout can take from 9 – 22 months to reach a marketable size of 0.5 to 1.0 kg.
What they eat…
Farmed trout are fed nutrient – dense digestible feed pellets which the fish convert efficiently. While fish meal remains a component of trout feeds, great efforts have been made to lower the reliance upon fish meal by substituting other protein sources such as soybean and corn meal. In fact, in the past decade, the percentage of fish meal used in trout feeds has decreased by about 50% as a result of the use of these alternate protein ingredients.
Reliance upon fish meal has also been decreased through improvements in the feed conversion efficiency of trout. For example, while rainbow trout once required 2 kg of feed for every kg of weight gained, today only about 0.5 kg (or less) of feed may be required.
Why they’re environmentally sustainable…
Canadian trout farms are well regulated and monitored to ensure that they maintain a very high standard of environmental responsibility. To reduce feed wastage, many trout farms now use demand feeders. Demand feeders require the fish to hit an object in the water in order to initiate the release of feed – so feed is only released into the water when the fish are hungry. Waste levels in effluent are regularly evaluated to ensure minimal impact on the surrounding environment. As well, fish health is strictly monitored to ensure that the farmed trout pose no threat to wild fish species. Best Management Practices, research and development, innovative production methods and the implementation of ‘green’ technologies ensure that trout farms are environmentally responsible and environmentally accountable.
Did you know…
Rainbow trout are relatively easy to culture. This amazingly versatile species can tolerate a wide range of water temperatures (from 0-27˚C) and there are numerous freshwater sources in which they can be grown: they thrive in water originating from aquifers, springs and streams – as well as in lakes. They can even be cultured in seawater where they are referred to as steelhead. This versatility makes them ideal for Canada’s diverse fresh and saltwater environments. Farmed Rainbow Trout are an excellent source of Omega-3 Essential Fatty Acids and are available at most grocery stores across North America in the form of bone-out fillets and whole dressed fish.
Northern Ontario Aquaculture Association: www.ontarioaquaculture.com
University of Guelph Aquacentre: www.aps.uoguelph.ca/~aquacentre
Aquaculture Association of Canada: www.aquacultureassociation.ca