No. A comprehensive study into dozens of possible threats that may have affected the return of Fraser River sockeye (2009) did not find salmon farms to be having a significant negative impact.
The $35M Cohen Commission of Inquiry reviewed 600,000 science documents and found the “primary factor” affecting the 2009 return to be environmental factors that reduced the production of food (plankton) for the juvenile salmon outmigration. The very next year (2010) the largest return of sockeye (in 100 years) returned to the Fraser River, and was repeated again in 2014.
The Inquiry’s final report included these two conclusions:
“I am also satisfied that marine conditions in both the Strait of Georgia and Queen Charlotte
Sound in 2007 were likely to be the primary factors responsible for the poor returns in 2009.
Abnormally high freshwater discharge, warmer-than-usual sea surface temperatures, strong winds, and lower-than-normal salinity may have resulted in abnormally low phytoplankton and nitrate concentrations that could have led to poor zooplankton (food for sockeye) production.” (Volume 3, page 59) “…data presented during this Inquiry did not show that salmon farms were having a significant negative impact on Fraser River sockeye…” (Volume 3, page 24). The US-based Monterey Bay Aquarium’s Seafood Watch program announced (on September 18, 2017) the upgrade of BC Atlantic farm-raised salmon to “good alternative”. As noted by the BC Salmon Farmers Association: Seafood Watch has indicated that this improved rating is due to an increase in independent, transparent, peer reviewed data on the subject of disease transfer between farmed Atlantic salmon and wild salmon populations in British Columbia. There were also improvements to the effluent, habitat, escapes and introduced species criteria.
The Seafood Watch report highlighted the initial results from the Pacific Salmon
Foundation’s Strategic Salmon Health Initiative and other research noting that, while although a level of concern is warranted, there is currently no evidence that there is any impact from salmon farms to wild salmon.