Shock as 200,000 fish die after salmon-killing jellyfish go on rampage

A deadly jellyfish species has reportedly wiped out over 200,000 salmon in Scotland, marking what is believed to be the worst incident of its kind.

The String of Pearls Jellyfish (Apolemia uvaria), also known as string jellyfish or barbed wire jellyfish, has attacked two Scottish salmon farms, according to The Green Britain Foundation.

The foundation claims that this species has previously caused chaos in Norway’s salmon industry, killing more than three million salmon in Norwegian farms in winter 2023.

Footage released by the foundation just two days before the official detection of the jellyfish attack shows tonnes of salmon of varying sizes being removed from the site.

The venomous tentacles of the string jellyfish inflict excruciating burns on the salmon’s skin, eyes, and gills, leading to a devastating assault. Trapped in densely packed pens, the salmon cannot escape the relentless stings, resulting in gaping wounds and immense stress.

These injuries make the fish highly susceptible to infection and disease, often leading to a slow and agonising death if left untreated. Animal experts have described the attack as “a true horror experience for animals with no means of escape.”

This incident is believed to be the single worst involving these jellyfish on a farm in Scotland.

Dale Vince, founder of the Green Britain Foundation, views this event as further proof of the need for stricter regulation of the salmon farming industry.

He warned: “This jellyfish attack is the latest example of how the fish farming industry is failing to cope with environmental challenges.We routinely see them using the land and sea as a sewer for their toxic business, and now nature is fighting back.

“It’s time for real accountability and for these companies to face the consequences of their actions”. The arrival of the jellyfish serves as a stark warning about the “devastating economic and ecological consequences” of open-net salmon farming.

As climate change continues to disrupt marine ecosystems, these farms are increasingly exposed to unpredictable and catastrophic threats.

Environmental experts say this incident highlights the urgent need to phase out open-net farming entirely, but until then, stricter regulations and robust environmental safeguards must be enforced to prevent further damage.

Recent reports from Norway suggest that the threat of jellyfish to salmon farms is ongoing and potentially increasing. In late October 2024, Norway’s regulator, the Norwegian Food Safety Authority, warned salmon farmers to prepare for jellyfish attacks.

The authority advised farmers to put measures in place to deal with the impact of jellyfish on their fish stocks, as recent attacks by string jellyfish had killed a large number of salmon.

The authority reported that jellyfish had been observed in numerous production areas, causing severe burns to the skin and gills of salmon, putting them at high risk for infection and disease.

A representative for the owner of one of the salmon farms involved acknowledged that jellyfish blooms can impact salmon health in various ways.

“To manage this emerging threat, intensive monitoring programmes are in place at Mowi’s salmon farms across Scotland,” a spokesperson for Mowi Scotland stated.

“There are daily tracking efforts, which involve water sampling, species identification and counts, and temperature and oxygen monitoring at various depths. ”We analyse trends daily to anticipate and mitigate conditions that might lead to harmful blooms.”

A Scottish government spokesperson emphasised the importance of farmed fish health: “While we do not have comprehensive information regarding which species of jellyfish are present on fish farms in every case of reported mortality, the salmon farming sector is focused on better understanding the impact of jellyfish as a cause of mortality.”