Mowi Scotland has reported the escape of 73,600 salmon with an average weight of 1.9 kilograms following damage to a pen at the company’s Colonsay farm during storm Brendan last week.
It comes in the wake of two large-scale escapes from Mowi sites at Hellisay, near Barra in the Outer Hebrides, in October and November.
In total, more than 120,000 salmon have escaped from Mowi Scotland fish farms on the west coast of Scotland this winter due to wild weather damaging cages.
All three escapes were from the Norwegian-owned firm’s new generation of high capacity offshore sites.
The Colonsay incident ranks among the 10 biggest known escapes from fish farms in Scotland and is the worst since 2014.
An estimated four million farmed salmon have been freed in more than 200 incidents since 1995, with scientific research showing that a quarter of wild Scottish salmon now carry genes from Norwegian farmed salmon due to hybridisation.
Mowi’s Colonsay net pen farm is one of the most far-flung and exposed in the world. Its construction exceeds both Scottish and Norwegian technical standards for net pens.
But an inspection following Storm Brendan found a structural failure in one of the 12 cages, which had caused a gash in the netting.
Mass escape from Colonsay
The company and equipment supplier are immediately reviewing the net pen’s manufacturing process.
David MacGillivray, Mowi’s regional farm manager, said: “We are very disappointed that this structural failure has occurred.
“Despite storm Brendan severely battering many parts of Scotland’s coast last week and Colonsay being a remote and particularly exposed location, we expect our modern infrastructure to withstand these challenges.”
The escapes have caused outrage among environmentalists opposed to fish farming.
Don Staniford, director of Scottish Salmon Watch campaign group, said: “Scottish salmon are being battered by storms, with mass escapes from disease-ridden salmon farms inevitable. “Moving salmon farms further offshore is a recipe for ecological and welfare disaster.”
Studies suggest hybridised salmon have poorer survival chances than native wild Atlantic salmon, sparking fears that escapes could drive further losses of declining wild populations.
Research published by the Royal Society of London in 2003 states: “We thus demonstrate that interaction of farm with wild salmon results in lowered fitness, with repeated escapes causing cumulative fitness depression and potentially an extinction vortex in vulnerable populations.”
This article was originally published as Storm Brendan causes mass escape of farmed salmon in Hebridean waters at The Scotsman on 21/01/2020.
Tags: Aquaculture, Fish Escape, Salmon Farm, Scotland