Atlantic halibut (Hippoglossus hippoglossus) is a marine, cold-water flat fish that is currently being developed as a commercial aquaculture species. It is a white-fleshed fish with high market value and demand, is an excellent species to complement and diversify the aquaculture industry.
Where they’re farmed…
Atlantic halibut are farmed in New Brunswick and Nova Scotia. Canada’s first commercial-sized farmed halibut were harvested from sites in the Bay of Fundy a couple of years ago, and show excellent market acceptance. Juveniles are produced in Nova Scotia at present and sold overseas. Development and commercialization of the industry in Canada requires significant capital for further expansion.
How they’re farmed…
To produce the highest quality farmed halibut, the very best adult female fish are selected each year as breeding stock. Halibut broodstock are maintained in onshore tanks – where each female produces several batches of eggs each season for well over 100,000 eggs per kg of body weight; these eggs are fertilized and incubated in the temperature-controlled tanks in a seawater hatchery.
Fertilized eggs hatch approximately 15 days after fertilization. Upon hatching, the halibut larvae are transferred to the ‘larval’ tanks. The newly hatched larvae are only 6 and 7 mm in length – barely recognizable as fish. During their first 50 days of life, the larvae receive nourishment from their yolk-sac. As the yolk sac is depleted, halibut farmers begin to feed the larvae a variety of small planktonic animals. This diet of plankton is gradually replaced with a high quality pelleted feed designed specifically for halibut larvae.
After approximately 50 days, the halibut larvae undergo a metamorphosis during which both eyes migrate to one side and they display the flattened appearance of adult fish. The young halibut are kept in circular tanks at the hatchery until they reach ~5 grams. The hatchery phase generally takes 6-7 months. Following this they undergo a nursery phase until they reach a size of 100-200 grams and are ready for deployment in sea cages.
Upon reaching this size, most juveniles are transported via transport tanks on large trucks and barges to sea cage sites in the ocean or to land-based on-growing facilities. To reach a targeted market size of 3-5 kg, it will take 24-36 months of on-growing where they are cared for and fed on a daily basis.
What they eat…
Halibut are fed pelleted feeds containing high quality ingredients such as fish oils, meals, vitamins and minerals that ensure an excellent feeding response and good growth. During the on-growing phase, halibut require only 1 to 1.5 kg of feed for every kg of weight gained.
Why they’re environmentally sustainable…
All approvals for halibut farms in Canada are subject to an intensive environmental review according to both federal and provincial legislation, including the Canadian Environmental Assessment Act (CEAA). Halibut farms can only be sited in areas where water currents provide optimal conditions for fish health and environmental sustainability.
Did you know…
An adult broodstock Atlantic halibut weighs between 50 and 125 kgs, larger than most humans. They are very powerful and one flick of the tail of a broodstock halibut can easily break a human arm or leg, if not handled with great care during the breeding process.
The shelf-life of fresh, head-on gutted halibut is up to three weeks on ice, much longer than most fish. The protective mucous on the fish’s skin contains hyppicin, a natural occurring compound produced by the halibut that prevents bacterial development and reduces spoilage after harvest.
Scotian Halibut: www.scotianhalibut.com
Ocean Sciences Centre, Memorial University of Newfoundland: www.mun.ca/osc/Home/
Aquaculture Association of Canada: www.aquacultureassociation.ca