Salmon farms have no impact on wild stocks states new study
Scottish peer-reviewed study calls for an end to the scapegoating of the salmon farming industry as the cause of population declines in wild stocks, while the ILO declares that aquaculture can feed the world.
By Fabian Dawson
Salmon farms have nothing to do with declining wild stocks, a seven-decade aquaculture analysis conducted in Scotland shows.
The peer-reviewed study by Dr. Martin Jaffa, an expert who specialises in the interaction between wild and farmed fish, has been published in the independent journal ‘Aquaculture & Fisheries .
“This analysis should end the scapegoating of the salmon farming industry as the cause of population declines in wild salmon,” Dr. Jaffa told SeaWestNews in a telephone interview from London.
A key aspect of the research report suggests that ‘cyclical patterns’ resulting from changing sea temperatures and variations in marine growth rates explain the fluctuations in wild salmon stocks – not the presence of farms.
“This analysis shows that between 1952 and 2010, catches of grilse (salmon that spend just one winter at sea) have steadily increased,” said Dr. Jaffa.
“Increasing numbers of grilse returning to Scotland’s rivers means that they cannot have succumbed to sea lice after making their way out to sea as some anglers claim, and thus salmon farms are not having a negative impact on wild stocks at all.
“Catches of large salmon may have declined, but they have declined across all of Scotland even in areas where there is no salmon farming.”
Dr. Jaffa’s paper analyses the Scottish government’s rod catch data from as far back as 1952, separating this into larger Atlantic salmon which spend up to four years at sea before returning to rivers, and the smaller ‘grilse’ salmon that spend just one winter at sea.
Previous research has usually combined these types of wild salmon, showing differences in trends between salmon in east and west coast rivers – which some campaigners have attributed to the presence of salmon farms on the west coast of Scotland.
However, the new data shows that overall numbers of larger salmon have declined in the east coast, where there are no farms – whereas there has been an increase in grilse catches on both coasts.
Further evidence in the paper shows that these cyclical patterns can be documented as far back as 1740, with trends showing that both larger salmon and grilse numbers go through peaks and troughs lasting over 50-year periods – and the recent proportional increase in grilse on the east coast is similarly matched on the west coast.
“Those concerned about safeguarding the future of wild salmon should start to address the real issues affecting wild salmon rather than scapegoating the salmon farming industry as the cause of population declines in wild salmon,” said Dr. Jaffa.
“If the salmon farms and sea lice in European waters have no impact on wild stocks here, one can expect them to be the same in the Pacific Northwest,” he said.
Ian Roberts, Mowi Director of Communications (Scotland, Canada, Ireland) said the new detailed Scottish study mirrors other studies in Canada that have included historical data to consider salmonid population impacts from human and/or natural events.
“When considering complete and 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 have always shown either no impact or minimal risk to wild salmonids from the activity of salmon farming, “ he said.
Scottish farmed salmon is one of the UK’s biggest food exports and worth more than £1bn a year to the economy. The industry directly employs 2,500 people.
But like on Canada’s west coast, the salmon farmers are under constant attack by activists, who have pushed their negative narrative about ocean-pen aquaculture by denying all science that challenges their unscientific observations.
In British Columbia, bowing to the demands of anti-fish farm activists, the Liberals have planned to transition all open-net salmon farms, despite its own government scientists saying that the maritime operations have less than a minimal impact on wild stocks.
Dr. Jaffa’s report comes in the wake of an International Labour Organization (ILO) technical meeting which affirmed that aquaculture has enormous potential to feed the world’s growing population in upcoming years.
“Sustainable and inclusive growth in the aquaculture industry could further be beneficial in terms of increasing income and livelihoods for many rural communities, both coastal and inland, and in this process, also contribute to governments’ efforts in alleviating rural poverty,” said Fatih Acar, the ILO’s government group vice-chair.
The meeting adopted conclusions that will assist governments, workers and employers to take measures to tap into the potential of the sector to support employment, as well as contribute to food and nutrition security.
A recent survey of 10,000 Canadians has found that most of them believe that ocean-based aquaculture is a sustainable way to raise and harvest salmon.
(Submitted image of Dr. Martin Jaffa)