Why is farmed salmon not considered sustainable?
There are several reasons why farmed salmon is not considered sustainable (please visit Farmed and Dangerous for more information). The main concerns are transfer of disease and parasites to wild stocks, pollution and the net loss of protein. Penned salmon live at high density that makes them susceptible to disease outbreaks. In particular, sea lice, which occur naturally, can achieve high densities on salmon in net-cages. When wild juvenile salmon pass by these farms, lice can be transferred to these young fish that are vulnerable to parasites. Some salmon farming companies are investigating the use of closed-containment systems in order to address these harmful impacts on wild salmon stocks, but this work is still in its early stages.
