JANUARY 25, 2012, 7:20 AM
Runaway Salmon Stir Conservation Worries
By DAVID JOLLY
As if the Loch Ness Monster wasn’t scary enough. Now, the Lox Ness monsters could be wreaking havoc in Scottish waters.
Meridian Salmon GroupA salmon cage.
The details are obscure, but sometime during a ferocious storm around Christmas, 300,000 farmed salmon owned by the Meridian Salmon Group disappeared from their cages in the sea near Uyea, a tiny island in the Shetlands. Their current whereabouts are unknown.
Tom Whittles, a Scottish government spokesman, said the tempest — with winds that reached as much as 100 miles per hour — washed 11 cages full of fish out to sea. After a search operation aided by government aircraft, the cages were finally recovered last week. But the fish themselves were not, according to the Scottish Salmon Producers Organization.
Conservationists worry about such escapes, partly because farmed fish are genetically less diverse than wild fish; interbreeding would have the effect of reducing the diversity and fitness of the offspring, making the wild salmon population more susceptible to disease.
Farmed salmon have also been known to infect their wild cousins with diseases and parasites. The Pure Salmon Campaign, which is no longer active, has reported that millions of farmed salmon escape into the wild each year.
Aquaculture itself is unpopular in some quarters because farmed fish must be fed several times their weight in wild-caught fish food before they reach marketable size.
Blue Planet Society, a conservation organization, mused in a blog post about whether the escape spellled ecological disaster. “There is a strong possibility that 300,000 farmed salmon are swimming about in the North Atlantic creating havoc in the marine ecosystem,’’ it wrote.
But Mr. Whittles argues that the fears are overblown. ‘‘It’s important to make a distinction between fish loss and fish escape,’’ he said.
‘‘You’ve got farmed fish that were used to being fed by humans suddenly exposed to extreme conditions,’’ and without food, he noted. ‘‘So there would certainly have been a high rate of mortality.’’
He defended the Scottish industry’s record, saying that reported escapes in 2010 were the lowest on record.
Mr. Whittles said the incident was being investigated by Meridian, the company’s insurers, and by scientists from Marine Scotland, a government agency. Meridian Salmon did not respond to requests for comment.
Matthew Thompson, an aquaculture specialist with the sustainable seafood program of the New England Aquarium in Boston, said it would be “very hard to have a firm sense of what the impact will be,” given the uncertainty on how many of the fish are still alive.
“Farmed Atlantic salmon, all the evidence suggests, are not good survivors when they do escape,” he said.
Salmon normally spawn in the rivers in which they were born. But these were all raised in tanks and therefore presumably will not be working their way back to breed.
Will they somehow find a way to spawn in the wild?
“That’s a good question,” Mr. Thompson said. “They’re not sterile.” The available evidence suggests that some escaped farmed salmon do eventually find a way to breed, he said. But it makes a very big difference if just a few survived or if tens of thousands survived, he added.
Aquaculture is big business in Scotland. The country ranks third globally as a producer of farmed Atlantic salmon, after Norway and Chile: in 2010 it produced more than 154,000 tons with an estimated value of $840 million, according to Marine Scotland.
The industry ranks as Scotland’s largest food exporter, and provides more than 6,000 jobs, but it has not been without controversy. After the Nobel Peace Prize was awarded last year by a Norwegian jury to a jailed Chinese dissident, Liu Xiaobo, causing Beijing indicated that it would retaliate against Norway by opening its booming market to Scottish salmon.
That raised concerns that Scottish aquaculturalists will try to raise more fish than their waters can sustainably support.