‘Barbed wire’ jellyfish reach UK waters

Attacks by Apolemia uvaria, known as string or barbed wire jellyfish, have been given as a contributory cause of mortalities in data provided to the Fish Health Inspectorate (FHI) in Scotland.

Among farms affected are Mowi Scotland’s site on Muck, Organic Sea Harvest’s farm at Invertote, Loch Duart’s farm at Gob na Hoe and the Scottish Sea Farms sites, at Slocka Ronas Voe and Olna South.

In November, Mowi alone recorded more than 56,000 mortalities where Apolemia was a factor. The FHI records show that exposure to the swarms of jellyfish can lead to gill health issues and bacterial infections. The necessary freshwater treatments can themselves lead to more casualties.

Apolemia jellyfish are colonies of individuals growing in long strings, and the poisonous tentacles can break off which makes it harder to keep them out of the pens.

In Norway, where Apolemia is known as “pearl norman”, last month Grieg was forced to cull thousands of fish after an attack in Finnmark.

Dale Vince, the eco-industrialist and founder of the Green Britain Foundation, which campaigns against salmon farming told the Guardian newspaper: “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.”