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The controversy surrounding the effects of aquaculture on wild salmon has grown almost as rapidly as the aquaculture industry itself. Conservation organizations like the Nova Scotia Salmon Association have been closely following the issues related to raising wild species in captivity because of the apparent direct connection between the presence of aquaculture and the decline of wild stocks.
The following summary provides some of the important pieces of information about aquaculture in Canada. It is not intended to be an in-depth examination of the effects of aquaculture on wild Atlantic salmon. Rather, the hope of the NSSA is that the visitor to this site will leave with a basic understanding of some of the issues raised by aquaculture in Canada.


General Facts

  • Domestic salmon were raised in Nova Scotia in 1967. In that year, Fisheries & Oceans worked in cooperation with a company known as Sea Pools Limited to conduct the country's first experimental salmon farms. The farms were located in Clam Bay, Nova Scotia.
  • In 1979, 6 tons of Atlantic salmon were harvested from sea pens in Passamaquoddy Bay, New Brunswick.
  • In 1999, 70,000 tons of domestic salmon were raised in Canada.
  • Currently there are approximately 30 companies in Canada operating more than 200 salmon farms on both coasts. Most raise domesticated Atlantic salmon and Rainbow trout.
  • The Maritimes account for slightly more than one third of Canada's domestic salmon output.
  • Approximately 90% of the Maritime production of domesticated Atlantic salmon comes from the Passamaquoddy and Grand Manan areas in New Brunswick. The remaining 10% comes from Nova Scotia and Newfoundland.
  • Aquaculture now accounts for more than 25% of all fish consumed by humans worldwide.
  • Salmon farming is the fastest growing sector in world aquaculture.


Species Characteristics: Domestic V. Wild

  • Domestic salmon have been selectively bred to grow faster than wild salmon and tend to be larger, less intelligent and more aggressive than their wild counterparts.
  • Studies have shown that domestic salmon grow at a rate of equivalent to ten times that of wild salmon.
  • Scientists claim that domestic salmon can be genetically engineered to grow up to 4 meters (12 feet) in length and weigh more than 80 kilograms (176 pounds).
  • Atlantic Salmon fare much better in captivity than Pacific salmon species so are preferred by the worldwide aquaculture industry.
  • Domesticated salmon now outnumber wild salmon by a factor of ten to one.


Dangers Presented by Aquaculture
General affects of aquaculture include:

  • loss of coastal habitat;
  • pesticide pollution;
  • greasy coatings on beach rocks;
  • waste deposits on tidal flats; and
  • increased present of algae in the water.

In Scotland, salmon farmers have been known to use a chemical delousing agent called dichlorpos to reduce infection of salmon by sea lice. Studies show that this chemical can kill oysters, mussels and other shellfish within 25 meters of the salmon cages where it is used.
It requires at least three kilograms of marine protein to produce a single kilogram of domestic salmon. Domestic salmon are fed by fish caught in the world's oceans.
Fish used to feed domestic salmon includes:

  • Herring;

Anchovy; and


Concerns are currently being raised around the world about the affects of genetically modified foods on human beings. Salmon that are being raised in aquaculture farms today may fall into the category of genetically modified foods.
In 1997, approximately 300,000 Atlantic salmon were accidentally released into Puget Sound, British Columbia.
In Norway, it is estimated that as many as 1.3 million salmon escape from farms every year and one third of salmon spawning in coastal rivers in Norway are escaped domestic salmon.
Escaped domestic salmon compete with wild salmon for food and for spawning habitat. Studies from British Columbia demonstrate that domestic salmon have begun to spawn and colonize in areas formerly occupied by wild Pacific salmon.
In Norway studies indicate that there are areas where escaped domestic salmon have completely engulfed the historic range of wild salmon.
Interbreeding between wild and escaped domestic salmon can result in the creation of "bad genes". Fish with these types of inferior genes may lose the ability to spawn and survive. The fish may not know where to spawn or may try to spawn at the wrong time of the year.
Escaped domestic salmon can carry disease that is spread to wild salmon populations through mixing in the ocean and interbreeding. Diseases that have spread from domestic species to wild species include:

  • infectious hematopoietic necrosis virus;
  • acterial kidney disease;
  • Whirling Disease;
  • Parasitic infections including Gyrodactilus; and
  • Infectious Salmon Anemia ("ISA").

Studies in Scotland have shown that if a river is less than three miles long and flows into the sea in an area where a salmon farm is located, the river's indigenous wild population will be dead.


Role of Federal and Provincial Governments

  • Fish farming creates jobs and generates economic activity in economically depressed regions and is politically attractive.
  • DFO has effectively shut down its Atlantic salmon research activities and has transferred hatchery salmon rearing to private organizations.
  • Between 1985 and 1999, the Atlantic Canada Opportunities Agency ("ACOA") pumped in more than $34 Million into the New Brunswick salmon aquaculture industry.
  • In October 1999, Yves Bastieu, Aquaculture Development Commissionaire for DFO, stated in an address to an aquaculture industry group that he believes the 20th century will be viewed as the point at which mankind goes from fishing to aquaculture.
  • In August 2000, Minister of Fisheries & Oceans, Herb Dahliwal, announced Ottawa would commit $75 Million dollars over the next five years to develop Canada's aquaculture industry.
  • DFO has never exercised any of its powers under the Fisheries Act to protect wild fish populations from any dangers presented by aquaculture.


Possible Remedies for Dangers Presented by Aquaculture

  • It has been suggested that salmon farms be located entirely within land-based pens fed by salt water to create a closed containment system. This type of landlocked system would eliminate the dangers presented by domestic escapees to wild salmon, such as disease, gene weakening and habitat competition. The aquaculture industry opposes this measure because of the costs associated with creating the pens.
  • Federal researchers continue to make breakthroughs in producing sterile, all-female strains of domestic salmon that could reducee threats to wild salmon from cross-breading with farm escapees.
  • DFO has stated that it is only a matter of time before a suitable seed-based food concentrate can be used to replace marine protein for feeding domestic salmon.

The NSSA continues to be concerned by the impacts of fin-fish aquaculture and will continue to monitor aquaculture activities that affect Nova Scotia waters. To date, the Association has not developed a formal aquaculture policy. The approach the Association has adopted is to address local issues on an issue-by-issue basis. However, as the NSSA learns more about the impact of aquaculture on our environment, and wild salmon stocks in particular, the Association may move to formalize its views on the industry.