Escapes: Net-pens are poor containment structures and escaped farmed salmon can compete with wild salmon for food and spawning habitat
Nets can tear and when they do, farmed salmon escape through the holes. Over one million farmed salmon escaped into B.C. waters between 1987 and 1996. Efforts to improve the situation have met with only marginal success. In 2008, 111,000 farmed salmon were reported to have escaped from salmon farms in B.C.
In 2009, one escape of 47,000 Atlantic salmon was not reported to the public until after fishermen began catching Atlantic salmon in their nets. At the end of 2010 another 15,700 Atlantic salmon escaped into B.C. waters from a farm using the latest net-pen technology and was only made public in the parent company’s quarterly report. Escaped farmed Atlantics can compete with Pacific wild salmon for food and habitat, disturb or disrupt the spawning behaviour and redds (egg nests) of wild salmon and spread diseases and parasites to the wild fish.
Over 180,000 Atlantic salmon escaped from open net-cage farms on Canada’s East Coast during the last three months of 2010. Escaped Atlantic salmon are known to interbreed with wild Atlantic salmon and can dilute the genes of the wild salmon making them less fit for survival. Wild Atlantic salmon in the Bay of Fundy and southern coast of Nova Scotia are recommended for listing as an endangered species and salmon aquaculture has been identified as posing a threat to wild Atlantic salmon stocks.
While Atlantic salmon cannot breed with Pacific salmon, in 1998 escaped farmed Atlantic salmon were found to have produced young in the Tsitika River on Vancouver Island. Atlantic salmon have been spotted in over 80 B.C. rivers and have been caught by fishermen in Alaska over 250 kilometres from the nearest salmon farm.
The salmon aquaculture industry has a poor track record in recovering escaped fish and has publicly admitted it is very unlikely that 10 percent of escaped fish are recovered. Only specifically designated fishing vessels can be legally used for recovery and the vessels, based in coastal communities, often take hours, if not days, to arrive at the remote farm location of the escape event.
Major escape events are reported to government regulators but fish also frequently escape through ‘leakage’. Small tears in nets may go unnoticed until scheduled inspections are undertaken and meanwhile, a few – or several – fish can escape every day until the hole is repaired.
Rearing farmed salmon in closed containment facilities that place an impermeable barrier between the farmed fish and the marine environment could help reduce the problem of escapes from fish farms. Closed containment systems on land would eliminate it.