In 2008, Jennifer Ford and Ransom Myers of Dalhousie University published a study entitled: A Global Assessment of Salmon Aquaculture Impacts on Wild Salmonids. They compared the abundance of five species of wild fish (salmon & trout). They collected data before and after aquaculture was placed in 5 regions and they compared exposed and non-exposed populations in similar regions. This study found that in multiple locations in Canada and Europe the presence of salmon farms reduced wild salmon survival by more than 50 percent per generation. The study is linked below:
Summary
Full Text of Study
Abstract:
Since the late 1980s, wild salmon catch and abundance have declined dramatically in the North Atlantic and in much of the northeastern Pacific south of Alaska. In these areas, there has been a concomitant increase in the production of farmed salmon. Previous studies have shown negative impacts on wild salmonids, but these results have been difficult to translate into predictions of change in wild population survival and abundance. We compared marine survival of salmonids in areas with salmon farming to adjacent areas without farms in Scotland, Ireland, Atlantic Canada, and Pacific Canada to estimate changes in marine survival concurrent with the growth of salmon aquaculture. Through a meta-analysis of existing data, we show a reduction in survival or abundance of Atlantic salmon; sea trout; and pink, chum, and coho salmon in association with increased production of farmed salmon. In many cases, these reductions in survival or abundance are greater than 50%. Meta-analytic estimates of the mean effect are significant and negative, suggesting that salmon farming has reduced survival of wild salmon and trout in many populations and countries.
