Impacts of Escaped Farmed Salmon on Wild Salmon
Wild salmon from different rivers are genetically distinct and have uniquely adapted to their individual native river since as far back as the last Ice Age.There is compelling international evidence to show that escaped farmed salmon pose a high risk to wild salmon populations. Negative effects include both ecological interactions and the genetic impacts ofinter-breeding.
Inter-breeding of farmed salmon with wild salmon has the potential to genetically alter native populations and reduce their ability to survive.
Repeat escapes of farmed salmon causes serious on going damage to wild stocks and can lead to salmon extinction in their native rivers, particularly where wild stock numbers are low. In Norway, all classified wild salmon rivers have been negatively impacted by farmed salmon escapes. 8 salmon rivers have been critically threatened or have lost their native wild stocks, 107 salmon rivers are classified as “threatened” or “vulnerable” while 211 rivers are classified as “in need of special attention”.
A recent genetic study in Scotland has shown evidence of the presence of Norwegian strain farmed salmon at almost all of the Scottish sites surveyed and confirmed several cases of direct escapees sampled in the wild. The levels of inter breeding between farmed and wild salmon along the Scottish west coast was significant.
Annual escapes exceeding half a million farmed salmon are reported regularly in Norway. In Ireland, the primary cause of escapes from salmon farms has been storm damage and a single escape of over 80,000 farmed salmon has occurred in recent years.