Aquaculture, or commercial/non-commercial salmon farming, has had a great impact on Fraser River. Several organizations and biologists claim that salmon farming located along west Coast of BC are responsible for the dramatic decrease of wild sockeye salmon in the Fraser River in 2009. Salmon farming not only poses an impact on wild salmon themselves but also on water quality and human health.
Impact of aquaculture on wild fish habitat
Sea lice
The high concentration of farmed salmon promotes the development and frequent occurrence of sea lice. Sea lice are parasites that occur naturally in low numbers in the water habitat. In the natural marine and freshwater environment, sea lice attach onto the adult salmon and feed on mucous and skin. They do not damage or physically harm the adult fish; however, with the establishment of commercial salmon farming, sea lice parasites on juvenile salmon pose a great threat or even death to the young fish.
The juvenile salmon become infested with sea lice during their passage along salmon farming areas on their journey back to the Fraser River. The sea lice infestation is therefore considered a major suspect in decline of Fraser River sockeye in 2009.
Fish escaping and cross-breeding
The farmed salmon are not native to BC; they are mostly Atlantic species. The farmed salmon are held in open cages, or net-pens. The torn or damaged pens provide an easy escape route for the farmed salmon and their entry to the wild fish habitat. The escaped fish compete with wild salmon over food and shelters, transfer diseases and pathogens, and also interbreed with them.
Impact of aquaculture on water quality
Aquaculture has negative impact on the quality of water. A high concentration of fish in the net-pen results in the occurrence of pathogens and diseases. To prevent this, farmed fish are fed with antibiotics and pesticides to prevent the spread of these diseases and pathogens. Chemical residues from uneaten food and fish faeces contaminate the ocean floor and the water in the direct vicinity of the farms. The waste can be carried away by the ocean current and cause pollution in other marine and fresh water ecosystems.
Impact of aquaculture on human health
From the human perspective, the salmon farm poses a direct threat to human by ingestion. The threat to human health rests in the high amount of pesticides, antibiotics residue, and food additives (to color grey fish meat to pink). Frequent ingestion of farmed fish can pose health risks, including cancer and resistance to antibiotics.
Salmon farm map and locations
The following links provide information on current salmon farms and locations:
http://www.agf.gov.bc.ca/fisheries/licences/cabinet/detailed_mw_farm_sites.pdf
http://historic.wildernesscommittee.org/wildpacific/salmon_farms/maps/bc_fishfarm_map.jpg
