THE TIMES (London, UK)
Fish farm lice are killing wild salmon
Jerome Starkey, Countryside Correspondent
January 15 2018, 12:01am, The Times
Sea lice that thrive on commercial salmon farms are killing tens of thousands of wild fish in Scottish, Irish and Norwegian waters.
Up to 50,000 wild salmon die as a result of the parasites in Norway, a review of more than 100 scientific papers found. Similar conditions in Scotland and Ireland meant that intensive salmon farming had a “general and pervasive negative effect”.
Wild salmon spend most of their lives at sea but return to the rivers where they were born to spawn. Young fish are particularly vulnerable to lice, which cling to their flanks and eat their flesh, if they have to swim past farms in estuaries on their journeys.
Sea trout, which are part of the Salmonid family, are also affected because farms are often located in the mouths of lochs and fjords.
“Considerable evidence exists that there is a link between farm-intensive areas and the spread of salmon lice to wild Atlantic salmon and sea trout,” the report by the Norwegian Institute for Nature Research (Nina) said. “In sum, the combined knowledge from scientific studies provides evidence of a general and pervasive negative effect of salmon lice on Salmonid populations in intensively farmed areas.”
Fewer wild fish return to areas where salmon are intensively farmed, the report said. Eleven lice can kill a fish and those that survive suffer skin lesions, fin damage and struggle to swim. They are also more susceptible to infections.
Andrew Graham-Stewart, director of Salmon & Trout Conservation Scotland which commissioned the research, urged the Scottish government to give wild fish more protection. “All too often Scottish salmon farm operators are incapable of keeping [sea lice] under control,” he said.
Scotland has more than 250 salmon farms which produced 172,000 tonnes of fish in 2015.
Farmers have tried bathing fish in hydrogen peroxide and warm water to limit the numbers of sea lice after the insects developed resistance to the primary pesticide, Slice.
Scott Landsburgh, chief executive of Scottish Salmon Producers’ Organisation, said that the impact of farms on wild salmon was minimal. “The authors have rewritten much of their own work a second time round,” he said. “There is no acknowledgment of the impact of climate change which is undoubtedly having an effect on wild and farmed fish health across the board.”
Separate research by the conservation trust suggested that up to 20 million fish a year had died on Scottish salmon farms, largely as a result of infectious diseases and parasites.