Salmon Aquaculture

Case Study

Wild salmon

Wild Salmon

Some wild Pacific salmon populations are endangered, mainly because of the loss of their fresh water habitat caused by harmful logging practices and hydroelectric dams. Salmon have also been over-fished in some areas. The Atlantic species of wild salmon is almost non-existent in U.S. waters but Pacific salmon are still commercially fished in areas where their populations remain strong. Many of these sustainable, limited-entry fisheries, from Alaska to California, have been or are being certified for a consumer eco-label by the Marine Stewardship Council. Fresh wild salmon is available seasonally, but frozen, canned and smoked products from these sustainable fisheries can be bought year-around.

Farmed salmon

The vast majority of salmon products sold in stores and restaurants in the U.S. are not wild, but farm-raised Atlantic salmon grown in the Pacific waters of British Columbia and Chile. This type of open, net-cage aquaculture has become very controversial because many scientists and fishermen consider salmon farms to pose a serious threat to wild salmon. One reason is because large numbers of farmed Atlantic salmon often escape their netcages into the wild. Given that many Pacific populations are struggling to survive the degradation and loss of their freshwater streams, there are fears that escaped Atlantics might out-compete the native fish for the available habitat, adding another threat to wild salmon.


Salmon getting anti-viral injection

Most salmon farms are located in areas where wild salmon migrate. The floating netcages that confine the farmed fish are usually stocked at high densities to maximize profit, creating conditions that are conducive to outbreaks of contagious disease and infestations of parasites. The salmon aquaculture industry has been plagued by a number of viral and bacterial pathogens that at times destroy thousands of farmed fish. Many marine scientists are concerned that the unnatural amplification of these diseases within the netcages threaten surrounding marine life and wild salmon. Infestations of sea lice are common in salmon farms and there is evidence in British Columbia and Scotland that the infestations have had negative impacts on wild juvenile salmon that swim near the netcages as they migrate out to sea.