Salmon deaths double in Scotland’s fish farms – but is jellyfish to blame? | Marine life

Official figures showed that salmon deaths on fish farms in Scotland nearly doubled last year, due to increasing levels of disease, parasites and jellyfish proliferation. Activists blamed the overcrowding and called for a boycott.

Fish Health Authority (FHI) data shows almost 15 million salmon deaths were reported by farms in Scotland from January to November 2022, the latest data available, compared to 8.58 million in all of 2021 and 5.81 million in 2020.

Atlantic salmon production has remained broadly stable at around 200,000 tonnes annually for the past four years, with some estimates as many as 77 million fish being farmed annually.

Salmon farmers have blamed the increase on unusually large numbers of tiny jellyfish that swept British waters last year, a phenomenon that could be linked to climate breakdown, but Abigail Penny, chief executive of Animal Equality UK, said overcrowding at salmon farms was to blame. that. .

“Deaths in fish pens have reached record levels for a number of reasons,” she said, “including a sharp rise in infectious diseases among fish packed in abnormally overcrowded cages, as well as poor gill hygiene and rough treatments to remove lice from infested waters.”

“As the industry grows, so do these problems. We must take back power and boycott farmed fish—it’s the only way we can rein in this problem, which is getting worse.”

Salmon mortality rates

The Fish Health Inspectorate, part of Marine Scotland, is responsible for monitoring 213 seawater sites in Scotland for salmon farming. A Scottish Government spokesperson said farms have a voluntary agreement to report salmon deaths over certain thresholds.

The spokesperson said: “Death reports list multiple factors – eg gill problems, bacterial or viral infection, handling, or predation – so it is not always possible to assign deaths to a specific cause.”

However, the health of the gills remains a major issue. There has been an increase in attributing environmental issues, including jellyfish and plankton blooms, and bacterial infections as a cause of deaths in 2022.”

According to the Marine Conservation Society, the seas around the UK have increasing numbers of jellyfish.

Salmon accounts for 29% of all fish sold to UK consumers, who spent £1.2 billion in stores last year, and about a quarter of Scottish salmon is exported.

Salmon in their cage. Small fish are introduced by the Loch Duart Company to control fish lice. Image: Murdo MacLeod/The Guardian

Atlantic salmon are raised in net pens up to 160m wide in Scottish waters including the longest marine loch, Loch Fyn, meaning that farms are exposed to the natural environment and marine ecosystems are affected by agriculture.

During their two-year life cycle, farmed salmon are vulnerable to extreme weather, predators such as seals and sea lice, and disease, especially when the waters are warmer during September and October.

Drone footage collected by Animal Equality UK shows workers using a ‘sock mort’ to scoop dead fish from the bottom of pens.

“I’ve been kayaking out to the farms at five in the morning in the summer when it’s light, before they start working, and you see dead fish lying on top of the cages,” said Don Staniford, of Scammon Campaign Scotland. . “The others have sunk to the bottom. So the first thing they do is collect the dead fish.”

Staniford said the FHI numbers for salmon deaths are likely an underestimate because not all deaths need to be recorded.

“About 25% of salmon in sea cages die, about one in four,” he said. “If climbers saw one in four cows or a sheep dead in a field, they would be horrified, but since it is underwater, it is out of sight, out of their mind.”

He pointed to sites with massive mortality rates, with one farm in Loch Nevis reporting a cumulative mortality rate of 64% last November. “There is no ethical way to farm salmon,” he said. “They’re working liberally on the Scottish environment, impacting local communities that depend on tourists, and there’s an impact on the welfare of fish farms.”

Scottish Salmon said jellyfish blooms could force the site to close or fall flat, with farmers harvesting all the fish.

Tavish Scott, chief executive of the industry body, said: “Wild Atlantic salmon have a survival rate of just 1-2%, compared to around 85% for farm-raised salmon.

“Throughout the year there will be different environmental pressures affecting survival rates. Farm-raised Scottish salmon usually face the biggest challenges in the autumn when seawater temperatures are at their peak.

“Salmon farmers look after their fish every day and do everything they can to provide world-class standards of animal health and welfare, so it is devastating that the fish in their care are facing naturally occurring challenges.

“We are working with industry and academia to develop an early warning system that will help protect fish from future jellyfish blooms.”

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