The search is being intensified for 12 large salmon cages which went adrift south of Unst during the hurricane-force storm on Christmas night.
A specially-commissioned spotter plane has been called to search the area where the pens containing around 1,000 tonnes of salmon are believed to be located. The latest air search comes after a previous flight was called back because of harsh weather conditions.
Meanwhile management at Meridian Salmon Group, which owns the cages, have called upon a Danish tug to help deal with the salvage operation once the cages are finally tracked down.
A local trawler was commissioned this afternoon to join the search, while the fisheries protection vessel Hirta has also been requested.
Around 300,000 salmon worth an estimated £3 million were being held in pens at Winnaness when they broke free from their moorings during the festive storms.
The fish, which are now assumed to be dead, were last seen around 40 miles east of Whalsay.
Losing the pens will have a detrimental impact on the business and its suppliers, and is likely to have a knock-on effect on the company’s Mid Yell processing factory.
The worrying discovery was made on Boxing Day, when staff informed the coastguard and the Scottish government of their disappearance.
Coastguard officers put a warning out to shipping and aircraft operators in the area to keep a look out for the cages.
After Christmas the crew of the Sumburgh-based rescue helicopter located the pens.
The company then arranged for two wellboats to come to the area for a recovery operation.
But a tow from one of the vessels, the Victoria Viking, broke 35 miles east of Whalsay before weather deteriorated and darkness descended, which prevented a second attempt from taking place.
Earlier this week a Marine Scotland spotter-plane was also summoned from Inverness to continue the search, following further talks with the coastguard service. It was pulled back because of continuing poor weather in the Highland capital, but is due to make a repeat attempt tomorrow.
Meridian’s managing director Mark Warrington is in Shetland with the company’s seawater director Colin Blair to oversea efforts to retrieve the pens.
Mr Warrington said the company was keen to prevent a similar incident from happening again.
“Given what has happened and the extremes of weather we have seen we do need to have a rethink, and we will carry out a full assessment of all our installations. We have been in touch with Norwegian consultants.”