Disease Transfer

High concentrations of fish in open net-cages provide the perfect conditions for the breeding of disease and the spread of disease to wild stocks. Both wild and farmed salmon can catch naturally occurring diseases such as the highly contagious Infectious Hematopoietic Necrosis (IHN), Infectious Salmon Anemia (ISA), Furunculosis, Bacterial Kidney Disease and various species of Vibrio.[1]^{,[2],[3],[4],[5], [6]} However, the effects of such diseases on farmed and wild stocks are very different. In the wild, sick fish no longer able to keep up with the rest of the school become easy prey for predators and do not linger to infect other fish. The density of fish within a farm, however, and the continuous presence of sick fish can cause disease to rapidly spread and amplify throughout the farm.

ISA has recently (2009) devastated the salmon aquaculture industry in Chile.[7]^{,[8],[9],[10],[11],[12]}

Even when being treated with antibiotics and other drugs (see Introduction of "Therapeutants" into the Marine Environment) farmed fish may remain contagious, increasing the risk of transfer of the disease to nearby wild salmon.

There is also concern about how and where the carcasses of diseased fish (the "morts") are disposed of.[13]^,[14]

[1] http://www.worldwildlife.org/what/globalmarkets/aquaculture/WWFBinaryitem11788.pdf [2]

http://www.farmedanddangerous.org/page/disease

[3]http://www.thefishsite.com/articles/598/the-global-spread-of-infectious-salmon-anaemia

[4] http://www.puresalmon.org/diseases_parasites.html  

[5] http://cmte.parl.gc.ca/Content/HOC/committee/372/fopo/reports/rp1032312/foporp03/10-part3-e.htm  

[6] An Introduction to Aquaculture - A primer on the industry for B.C. First Nations http://fnfisheriescouncil.ca/index.php/mission-a-work-of-council/working-groups/aquaculture-working-group/557-nasapi-workplan-dec-2009  

[7] http://www.thefishsite.com/articles/598/the-global-spread-of-infectious-salmon-anaemia

[8] http://saveourrivers.ca/video-library-mainmenu-29/salmon-farming-chile  

[9] http://www.telegraph.co.uk/news/worldnews/southamerica/chile/6426435/Investigation-How-farm-fishing-boom-in-Chile-threatens-eco-disaster.html [

10] http://www.ncbi.nlm.nih.gov/pubmed/19034606

[11] http://www.theglobeandmail.com/report-on-business/canada-eyes-bigger-salmon-market-share/article1471669/  

[12] http://www.theglobeandmail.com/report-on-business/salmon-virus-tilts-scales-in-favour-of-british-columbia/article1480234/  

[13] http://www.puresalmon.org/waste_contamination.html  

[14] http://www.davidsuzuki.org/files/Leggatt_reportfinal.pdf