Sustainable aquaculture development can only be achieved by protecting the marine environment and the health of wild stocks.

Farmed fish that escape from net cages can affect wild stocks. However, with good quality management, this is also preventable. Escaped farm fish can be a significant economic loss to the individual fish farm operator. Both government and industry are aiming to minimize escapes to zero.

The majority of fish farm escapes occur as a result of storms with high winds, waves and currents that break anchor lines, pen structures and tear nets. Nets and pen structures can also be damaged by boat propellers, attacks by predators such as seals and sea lions or through human error and vandalism.

Provincial regulations and operating guidelines require aquaculture operations to submit escape prevention and recapture plans as well as record and report any escapes. The salmon farming industry has taken significant steps to reduce the risk of escapes by using advanced cage technology and management practices. The number of escapes has been significantly reduced over the past decade as a result of:

• improved farming techniques, management and maintenance of nets, and anchoring;
• increased provincial government regulation and monitoring;
• stricter guidelines for vessel operations near farms; and,
• improved staff training.

When salmon farming began in British Columbia in the late 1970s, farmers trying to raise Pacific salmon species encountered a number of problems including slow and unpredictable growth, low survival rates and poor product quality. Atlantic salmon were already being raised successfully in many other parts of the world, including Atlantic Canada and Washington State, and in the mid-1980s B.C. farmers began to raise Atlantic salmon.

Today, Atlantic salmon account for about 75 per cent of farmed-raised salmon in BC – Chinook and Coho account for the remaining 25 per cent. Atlantic salmon are favoured by aquaculture operators because they are more docile and often experience better growth and survival rates than do their Pacific counterparts. International market demand is also higher for Atlantic salmon and processors find they provide more meat and create less waste per fish.

There have been concerns that farmed salmon escaping from net pens could contribute to the decline in wild salmon stocks. Specifically, these include:

• escaped farmed salmon could establish in the wild and compete with wild salmon for habitat and food, potentially displacing already stressed wild stocks;
• disease and parasites could be spread between farmed and wild stocks; and,
• wild and farmed salmon could interbreed, further threatening the health of wild stocks.

Atlantic salmon were unsuccessfully introduced into the watersheds of British Columbia in the early 1900s in an attempt to establish runs for sport fishing. Similar results occurred in the state of Washington and several other countries.

The fact that self-sustaining populations of escaped farm Atlantic salmon have not established anywhere in the Pacific Ocean supports scientific opinion that the risk to wild stocks from escaped farmed Atlantic salmon is low.

Fisheries and Oceans Canada (DFO) research on the potential effects of escaped salmon indicates there are low levels of interaction between farmed and wild fish – either through competition for habitat and food or as predators.

Survival rates for escaped farmed salmon appear to be low. Farmed salmon, which are fed from birth, are docile and poorly suited to survive in the wild, especially against the more aggressive wild fish. Stomach content analysis of farmed Atlantic salmon recovered in the wild showed low intake of food and no trace of young wild salmon.

Farmed Atlantic salmon can successfully mate with wild Atlantic salmon. Little research concerning the genetic interactions between escaped farmed Atlantic salmon and wild Atlantic salmon has been conducted in North America. Research in Europe indicates that escaped farmed Atlantic salmon can have a negative impact on the genetic make-up of wild Atlantic salmon populations. However, it is too early to speculate or draw conclusions on the overall effect of escaped farmed Atlantic salmon on wild Atlantic salmon in Eastern Canada. DFO is conducting research in collaboration with the Atlantic Salmon Federation, which should help put more pieces of the puzzle in place.

The Atlantic Salmon Watch Program (ASWP), a federal-provincial research program established in B.C. in 1991, monitors and documents escaped Atlantic salmon year-round. In co-operation with the province, the ASWP monitors commercial and sport catches for Atlantic salmon in B.C., and relies on fishers, processors, and government and hatchery workers to report observations. In 2001, DFO partnered with provincial agencies and the B.C. Salmon Farmers Association to conduct the First Nations Atlantic Salmon Watch in which First Nations members surveyed streams for Atlantic salmon in their traditional territories.

DFO works with the Atlantic Salmon Federation on the East Coast to monitor four rivers in eastern Maine and the Magaguadavic River in New Brunswick for escaped farmed fish.

Fisheries and Oceans Canada – www.dfo-mpo.gc.ca

B.C. Ministry of Agriculture and Lands – http://www.agf.gov.bc.ca/fisheries

Escaped Farmed Salmon: A Threat to BC’s Wild Salmon?

B.C. Salmon Farmers Association – www.salmonfarmers.org/files/publication_envprot.html

Atlantic Salmon Federation – www.asf.ca

Note: This page contains links to Web sites not under the control of the Government of Canada.  For further information on our hyperlinking practices, please refer to the Hyperlinking Notice.