Mowi escape could involve as many as 27,000 mature salmon

The incident is one of the largest, and certainly one of the costliest salmon escapes for some time. With an average weight of 5.5 kg and ready for harvest , it would amount to a total financial loss of over £1.5m if none of the fish are recaptured.

But such a scenario is thought unlikely, so the eventual loss will depend on how many fish can be returned to the site.

Around 105,000 salmon were in the facility. If estimates turn out to be correct, 25% of the stock escaped.

It is little surprise that the company is offering a reward of NOK 500 (around £36) per fish that are recaptured. The weather is still hampering recovery operations, so the full extent of the loss will not be known until the wind abates.

Mowi Seawater Norway AS reported an escape incident during a storm from the company’s site in Storvika Vest in Troms, on Sunday.

The cage was badly damaged, presumably as a result of the storm which was particularly severe and has severely restricted salmon farming in that part of Norway. A mooring is thought to have caught fire.

The Directorate of Fisheries has ordered the company to expand its capture fishery. The Directorate is now present at the site and is following up on the incident with supervision according to normal procedures.

It said: “Let us know if you catch farmed salmon. We would like the public to tip us off about catching and observing farmed salmon in the area.”

The company said it was very regrettable that something like this should have happened, adding: “Mowi would like to extend its sincere thanks to the Coast Guard Ship Svalbard, and a number of other organisations and companies in addition to the very dedicated employees who participated in the operation under very demanding weather conditions.”