Seafood firm Young's is to cut 120 jobs - almost half the workforce - at its plant at Annan in south west Scotland.
Young's is to transfer de-shelling operations to Thailand
The company will transfer its breaded scampi de-shelling to Thailand in a factory owned by sister company Findus.
Director of scampi, Mike Mitchell, said it had been an "extremely difficult" decision but hand-shelling was not economically viable in the UK.
T&G union regional industrial organiser John Holroyd said the cuts were "absolutely devastating" for the town.
He said that there had been problems within the industry as a whole in trying to compete with overseas operations.
"It is the politics of the absurd," said Mr Holroyd.
"They can actually catch prawns in Scottish waters and ship them half way round the world to Thailand just to have them peeled.
"The savings the company can make are amazing."
He added that the announcement was not a good sign for the region as a whole.
"What does concern me - with Dumfries and Galloway being an agricultural economy - is that we are probably going to see a lot more of this in future," he said.
The company has said it remains committed to the south west Scotland plant despite the job reductions.
"This is an extremely difficult decision for us since it would involve the end of de-shelling at Annan with a loss of approximately 120 jobs," said Mr Mitchell.
"However, the change forms part of our wider plan to grow the whole market - langoustine is already the UK's biggest fishery by value and we believe this excellent seafood has huge potential."
Under the plan scampi will still be caught in the British Isles and be frozen, coated and packed in Annan before transfer to Thailand for de-shelling.
"The facility in Thailand has a long history in seafood processing and can undertake hand de-shelling for us to a very high standard," said Mr Mitchell.
"We are also satisfied that it provides proper pay and working conditions in line with our group commitment to responsible ethical trading standards."
Young's has advised employees and trade union representatives that it is entering into 90-day formal consultations.
A statement said it was hoped that some of the reduction in workforce could be achieved through natural wastage or possible transfer to other sites.
The company added it aimed to make the changes by February next year.
Young's has been producing seafood in Annan since the 1940s.
The site is the UK's largest breaded scampi facility, with about 250 employees.