Evidence for the Harmful Effect of Stock Enhancement and Commercial Farming on Native Gene Pools of Atlantic Salmon and Brown Trout

Impact: Environmental Impact, Public Policy Impact


The effects of accidental salmon farm escapes, intentional releases of non-native salmon and trout, and stocking of fertile farm-reared trout, on the genetic makeup, fitness and long-term viability of wild populations has been a matter of increasing concern over the past two decades. Ferguson and Prodöhl’s group demonstrated that offspring of farmed, first and second generation hybrid and backcrossed salmon and trout showed reduced survival compared with wild native fish, and that repeated escape/introduction events can cause a reduction in the biological fitness of vulnerable wild populations leading to reductions in numbers and potentially to their extinction. These findings led directly to changes in regulations and guidelines by relevant major stakeholders including the Environment Agency (England & Wales), Wild Trout Trust, North Atlantic Salmon Conservation Organisation, World Wildlife Fund, and governments in Europe and North America.
Impact statusOngoing
Category of impactEnvironmental Impact, Public Policy Impact
Impact levelAdoption