Salmon Farming Impact in Scotland

This is an extract from an article by Brendon Montague recently published on the UK website of “The Ecologist”. He interviewed three friends who moved to Loch Hourn in the Highlands of Scotland during the 1970s and have seen first hand the impact neo-liberal economics has had on the environment. This extract on salmon farming is significant in light of New Zealand’s fisheries minister Shane Jones’ enthusiasm for fish farming and ventures like King Salmon in the Marlborough Sounds. Note the Scottish farms farm Atlantic salmon, not chinook (quinnat) as in New Zealand.

The latest crisis is the incursion of open-net salmon farming on the southern shore of the loch. 

Farmed salmon is now the single most popular fish consumed in the UK, according to the Marine Conservation Society. 

The rationale for salmon farming, Peter Carr tells me, is simply that it was seen as “an exciting new opportunity for businesses and employment and another way to make money from the sea”. But the growth in the size of the salmon farms here has increased the concerns of people who have fished here for decades about the impact on the ecosystem. 

Mick Simpson, also a local fisherman, opens a meeting of the Friends of Loch Hourn (FoLH), of which Peter is a founder member, at the local community centre, a small chapel-like wooden building. I am lucky enough to be in attendance. The group was originally established to fight a planning application submitted by a company called Mowi Scotland. Mowi had farmed salmon at Loch Hourn for decades, and then applied to expand the fish produced at its facility by 24 percent. FoHL gathered 170 formal objections to the application and submitted them to the local planning authority. This is despite the fact that the group is run entirely by volunteers.

“At first we thought salmon farming was a good idea,” Mick concedes. The farms were small – at the beginning. Crofters whose families had farmed in the area for generations thought they might have a stake in the new economy, “to have their own cage to grow a fish farm”.

Almost Extinct

Wild Atlantic salmon populations in the Arnisdale River are close to extinction, while across Scotland they are at an all-time low. Indeed, populations of salmon have collapsed across Britain and were recently reclassified as “endangered” by the International Union for Conservation of Nature. It is widely known that a major driver for the collapse of wild salmon is climate breakdown, which brings warmer sea temperatures that in turn cause thermal stress and reduced oxygen levels in water, placing stress on the salmon and allowing sea lice to breed faster. However, commercial fish farming is certainly compounding the crisis.

The ecological crisis is only going to get worse unless action is taken.

Rachel Mulrenan, Scotland director at WildFish, said: “Open-net salmon farming is one of the key threats facing our iconic wild Atlantic salmon populations. The growth of open-net salmon farming in Scotland has coincided with a catastrophic decline in the wild salmon population. From the dispersal of sea lice parasites, which can prove fatal to migrating smolts, to the impacts of escaped farmed fish on genetic fitness, there is no doubt that salmon farming has been a significant contributory factor to this decline.”

The biggest problem right now is the outbreaks of sea lice.

 “In the early days they had a site right up the top of Loch Hourn in the inner lochs, which had to be abandoned when the minimal flow up there contributed to disease outbreaks,” I am told. 

Optimum disease conditions

Salmon farms are the perfect breeding ground for the parasites, which multiply and release huge quantities of juvenile lice which attack what remains of the wild Atlantic salmon. After being spawned, wild salmon live in the freshwater of the rivers for two to three years before growing into smolts and migrating out to the ocean. During this vital journey they are plagued by the sea lice that are pouring out of the fish farms and are concentrated along the path that the young salmon travel on their way to the open sea. One sea trout caught recently off Glenelg had over 30 sea lice attached. Mowi Scotland states that sea lice levels peaked in 2007 and have declined since following the use of “freshwater treatments” and other physical means such as thermolicers. 

The use of toxic insecticides, such as azamethiphos, to deal with the lice may even be adding to the environmental harm. These and other organophosphates are, according to locals, being released into the loch. 

Peter observes: “I can’t think of any other farming industry that would be able to do that.” 

The John Muir Trust has stated: “Important marine species in Loch Hourn which have already suffered from chemical pollution from the existing fish farm operations…include maerl beds, native oysters, wild salmon, sea trout, northern feather stars, tall sea pens and fireworks anemones.” 

Pollutants

The local community is also worried about the release of excess nutrients into the loch. The water interchange in the loch takes 11 days, which means these nutrients are not quickly dispersed. Salmon release ammonia from their gills, which breaks down into nitrogen. The increase in the production of salmon at the Mowi farm will inevitably increase the nitrogen in the water by the pens. An increase of nitrogen can result in algae blooms, which in turn suck oxygen from the water. In extreme cases, this can kill other species.

The increase in salmon also results in more carbon deposits on the seabed. The number of different species living under the fish farms is falling, although the population of some species, such as polychaetes, are increasing. Salmon also escape the farms. A total of 36,000 fish breached the Mowi facility at nearby Carradale in August 2020 during a storm, although the company states that its research showed this did not impact the wild populations. Mowi states that all nutrients and chemicals from the farms are closely monitored and kept within regulatory limits. 

The European salmon industry is having impacts around the world. 

Norway Farming

The Norwegian salmon farming industry has been strongly criticised for sourcing much of its feedstock –  fishmeal and fish oil – from West Africa. As a result, an estimated four million people in the region are suffering from chronic food insecurity. 

Peter says of salmon farming generally: “They will use a lot more wild fish feed to get a kilogramme of farmed salmon. You’re talking about fish that someone could have eaten off the coast of Africa.” 

Mowi Scotland has a policy of not sourcing marine foodstock from West Africa. It does import as much as four million tonnes of fish from Peru each year.

There is also widespread concern about the welfare of the fish caught up in industrial fish farming around the world. Peter, discussing the global industry, said: “The fish are being eaten alive by lice. They’re suffering. There’s no way that any of us would treat livestock the way that they’re treating the fish.”

In relation to Loch Hourn, he adds: “The mechanical treatments for lice infestation, such as thermolicers, are brutal. But even for healthy fish the conditions are completely alien, for a species that normally has a range of thousands of miles to be crowded into these cages for their short lives. In addition, I cannot think of any other livestock farming industry that would consider a 20 per cent mortality normal or acceptable.”

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