Salmon farms have no impact on wild stocks, new study finds

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Peer-reviewed Scottish study calls for end the salmon industry scapegoat as the cause of population decline in wild stocks, while ILO says aquaculture can feed the world.

By Fabian Dawson
SeaWestNews

Salmon farms have nothing to do with declining wild stocks, according to an analysis of aquaculture in Scotland over seven decades.

The peer-reviewed study by Dr Martin Jaffa, an expert specializing in the interaction between wild and farmed fish, has been published in the independent journal ” Aquaculture & Fisheries .

“This analysis should end the scapegoat for the salmon farming industry as the cause of the decline in the wild salmon population,” Dr Jaffa told SeaWestNews in a telephone interview from London.

A key aspect of the research report suggests that “cyclical patterns” resulting from changes in sea temperature and variations in marine growth rates explain fluctuations in wild salmon stocks – not the presence of farms.

“This analysis shows that between 1952 and 2010, catches of grilse (salmon that only spend one winter at sea) steadily increased,” said Dr Jaffa.

“The increasing number of grilse returning to Scottish rivers means that they cannot have succumbed to sea lice after taking to sea, as some anglers claim, and so salmon farms do not have to. any negative impact on wild stocks.

“Catches of large salmon may have declined, but they have declined across Scotland, even in areas where salmon are not farmed.”

Dr Jaffa’s article analyzes Scottish government pole-and-line catch data since 1952, separating it between the larger Atlantic salmon that spend up to four years at sea before returning to rivers, and smaller “grilse” salmon that only spend one winter at sea.

Previous research has generally combined these types of wild salmon, showing differences in trends between salmon from the east and west coasts – which some activists have attributed to the presence of salmon farms on the west coast of Scotland.

However, the new data shows that the overall number of large salmon has declined on the east coast, where there are no farms, while there has been an increase in grilse catches on both coasts.

Other evidence in the paper shows that these cyclical patterns can be documented as early as 1740, with trends showing that larger numbers of salmon and grilse cross peaks and troughs during periods of 50 years – and the recent proportional increase the number of grilse on the east coast corresponds in the same way to the west coast.

“Those concerned about saving the future of wild salmon should start tackling the real issues affecting wild salmon rather than making the salmon industry a scapegoat as the cause of population decline. wild salmon, ”said Dr. Jaffa.

“If salmon farms and sea lice in European waters have no impact on wild stocks here, we can expect them to be the same in the Pacific Northwest,” he said. -he declares.

Ian Roberts, Mowi’s communications director (Scotland, Canada, Ireland) said the new in-depth Scottish study mirrors other studies in Canada that have included historical data to take into account the impacts on salmonid populations of the events. human and / or natural.

“When considering comprehensive, long-term data, as did the Cohen Commission of Inquiry into the Decline of Sockeye Salmon in the Fraser River (2012) and Fisheries and Oceans Canada (2020), the results are always shown either no impact or minimal risk. wild salmonids from salmon farming, ”he said.

Scottish farmed salmon is one of the UK’s largest food exports and contributes over £ 1 billion a year to the economy. The industry directly employs 2,500 people.

But like on Canada’s west coast, salmon farmers come under constant attack from activists, who have pushed their negative rhetoric about ocean pen aquaculture by denying any science that calls their unscientific observations into question.

In British Columbia, bowing to the demands of anti-fish farm activists, the Liberals plan to transfer all salmon farms to netting, despite scientists in his own government claiming maritime operations have less than minimal impact on wild stocks. .

Dr Jaffa’s report follows a Technical meeting of the International Labor Organization (ILO) who claimed that aquaculture has enormous potential to feed the growing world population in the years to come.

“A sustainable and inclusive growth of the aquaculture industry could further be beneficial in terms of increased income and livelihoods for many rural communities, both coastal and inland, and in this process also contribute to the efforts governments to reduce rural poverty, ”said Fatih Acar. , vice-chairman of the government group of the ILO.

The meeting adopted conclusions that will help governments, workers and employers to take action to harness the potential of the sector to support employment, as well as contribute to food and nutrition security.

A recent survey of 10,000 Canadians found that most believe ocean aquaculture is a sustainable way to grow and harvest salmon.

(Image submitted by Dr Martin Jaffa)


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