Farmed Rainbow Trout / Steelhead Salmon
- Rainbow trout
- Steelhead salmon
- Oncorhynchus mykiss
Rainbow trout and steelhead salmon are the same fish. "Oncorhynchus” is Greek meaning "hooked snout”; this is common to all five wild Pacific salmon species as well as to rainbow trout/steelhead salmon which are also salmonids. "Mykiss” is the Kamchatkan name for rainbow trout. Rainbow trout refers to the fish when it is harvested or cultured in fresh water; steelhead salmon is the name used when the fish is harvested or cultured in salt water. In the wild, O. mykiss can be anadromous like salmon, each fish returning to its original natal river to spawn. However, unlike salmon, this fish can spend its entire life in fresh water, and so can be cultured in either fresh or salt water. While Canada has wild harvests of both rainbow trout and steelhead salmon, this fact sheet focuses on the fish as a product of aquaculture.
Rainbows and steelhead have small black spots along their back, dorsal and caudal fins. Rainbows have a pink streak that runs from the gill cover to the caudal fin. The colour of a rainbow's back varies from blue or green to a yellow-green or brown. Steelhead usually lack the pink stripe, except when young or spawning, and have chrome-coloured sides. Rainbow trout also lack hyoid teeth.
Although trout farms can be found in six of the 10 Canadian provinces, Ontario is the leading producer of rainbow trout in Canada. In 2006, Ontario produced 4,250 metric tonnes of rainbow trout worth (at farm gate) more than $16 million. This represents approximately 80 per cent of the entire Canadian output of farmed rainbow trout. Culture methods in Ontario focus on intensive recirculation facilities, flow-through or recirculation hatcheries, cage culture, and pond culture.
In Ontario, there are two principal trout-growing areas - (1) southwestern Ontario where tobacco farmers have diversified into trout aquaculture, and (2) northern Ontario, principally in the waters of Georgian Bay and Lake Huron, around Manitoulin Island where the water is more than 110 feet deep. Manitoulin Island, the world's largest freshwater island, has been home to trout farming since 1987.
There was a time when the farmers of southern and northern Ontario competed for share in major Canadian and US markets, but recently the industry has reorganized so that the farms in southwestern Ontario now provide fingerlings for the grow-out cages in the north, as well as for stocking fee-fishing ponds, and for enhancement of wild stocks. The deep, cold, clean waters of Lake Huron provide the ideal environment for raising rainbow trout; the fish convert feed to protein efficiently and grow to market size quickly. In addition, having one area hatcheries and grow-out sites separated means that cages can be stocked at different times of the year, thus ensuring market availability all year round.
Typically, fingerlings are introduced into the cages in May or June and by Christmas the fish have reached one pound. The goal is to market fish that are 2.5 pounds in size.
Feed and feeding techniques are very important elements of aquaculture. Feed suppliers are highly regulated and experienced in manufacturing pet food and feeds for livestock and poultry. Fish feed is composed primarily of fish meal (herring or anchovy), fish oil, soybean meal, and a healthy diet of vitamins, minerals and beta-carotene. This diet closely approximates the diet of wild salmonids to ensure that the outcome is a fillet with fresh, bright colour and excellent quality characteristics. To ensure maximum freshness, the fish are harvested to order and immediately chilled to the core. The fish are processed within hours and shipped out the same day.
Responsible Management and Environmental Practices
Trout farms in Ontario are regulated by 26 different federal, provincial and municipal authorities to ensure that they maintain the highest standard of environmental responsibility. Farms are sited in areas where deep waters and rapid currents allow for continuous flushing of cage sites. Farmers employ a variety of methods to keep sites clean. Some rotate cage sites, leaving some cages fallow in the same way terrestrial farmers will fallow fields; others collect and remove waste by suspending tarps under the cages. The Ontario Sustainable Aquaculture Working Group (OSAWG), initiated in 1999, works to identify information and technology needs for enhancing environmental performance in the aquaculture industry. The OSAWG has supported a number of projects in the Manitoulin Island area designed to prevent impacts to water quality and fish habitat.
Additionally, advances in feed technology and feeding techniques ensure that the correct amount of feed is given for the number of fish in the pen and that the feed is formulated to so that the maximum amount is absorbed by the fish. Feed that is not eaten is money wasted by the farmer.
Winters in Northern Ontario can be challenging and the ice in Georgian Bay and Lake Huron can easily damage both cages and fish. Farmers must keep water moving in winter by blowing air through the sites and keep the ice off the cages during the spring melt. At the same time it is these cold, clean waters that give Ontario rainbow trout its excellent flavour and texture.
Rainbow trout are available in a variety of product forms. Whole or dressed fish, fresh or frozen, fillets (frequently boneless with pinbones removed) and portions are found in most supermarkets. Value-added products such as breaded, stuffed, hot and cold smoked and marinated trout products are also popular and readily available.
In an effort to improve recovery, processors are using the backbone meat (formerly wasted) to create minced trout for value-added items such as breaded nuggets or pâtés. Yields are now up to 53 per cent on whole fish.
Other less traditional value-added products are also being created from rainbow trout. One Manitoulin Island trout farmer is creating a high-nutrient compost by combining trout waste and dead stock with sawdust from the local sawmill. Preliminary tests done on this compost material suggests that it could be one of the best fertilizers around, adding nitrogen to the soil, containing no seeds, holding moisture and adding humus without compacting. If brought to a commercial reality, this product could recycle 1.5 million pounds of fish and 4 million pounds of sawdust a year.
Rainbow trout has a mild, nut-like flavour; the flesh is pink or orange. The skin of the rainbow trout should be dark, shiny and have a slippery feel.
The variety of product forms and ease of preparation make rainbow trout a natural choice. Its oil content and large flake enable it to stand up to the barbeque and to most sauces, but its delicate taste and silky texture also shine under very simple preparations. Smoked rainbow trout can be used in dips and salads, left-overs can be made into sandwiches or wraps. The "Canadian rule” should be applied to cooking whole fish or fillets - measure the fish at its thickest part and cook 10-12 minutes for each inch (2.5cm) of thickness. Avoid overcooking any fish, but particularly rainbow trout. It has the best texture and flavour at the point where the flesh has just become opaque and flakes easily with a fork. Microwaving is especially suited to the high temperature and short time required for cooking trout - just 5 to 6 minutes are required for a one pound (450g) fish.
Source: Seafood Business
Farmed rainbow trout is naturally low in sodium and is an excellent source of complete protein and essential omega-3 fatty acids. A 3.5 oz (100g) serving supplies roughly 40 per cent of daily protein requirements, while the high levels of omega-3 fatty acids may help to lower blood triglycerides and cholesterol levels, reduce the risk of coronary and cardiovascular disease, reduce blood pressure and relieve the paid of rheumatoid arthritis. Farmed rainbow trout is also an important source of iron and B vitamins.
Safety and Wholesomeness Assured
Canada has one of the world's most comprehensive and respected fish inspection and control systems. The Canadian Food Inspection Agency (CFIA) sets the policies, requirements and inspection standards for fish products, federally registered fish and seafood processing establishments, importers, fishing vessels, and equipment used for handling, transporting and storing fish. All establishments which process fish and seafood for export or inter-provincial trade must be federally registered and must develop and implement a Quality Management Program (QMP) plan based on HACCP (Hazard Analysis Critical Control Points) principles. A processing establishment's QMP plan outlines the controls implemented by the fish processor to ensure that all fish products are processed under sanitary conditions, and that the resulting products are safe and meet all regulatory requirements. The QMP forms the basis of a farm-to-fork traceability system that allows farmed rainbow trout to be carefully documented and traced from the moment of harvest to its arrival in the marketplace. Canada's fish-inspection and control system contributes to Canada's worldwide reputation for safe, wholesome fish and seafood products. Buyers can be assured that seafood from Canada will continue to meet the increasingly rigorous safety and wholesomeness standards required by the world's major seafood markets.
NOTE: These processors are volume wholesalers and are not usually set up to deal directly with consumers.
- Northern Ontario Aquaculture Association
- Canadian Aquaculture Industry Alliance
- Aquaculture Department
of Fisheries and Oceans
- Date Modified: