Redundancies have begun at the Pinneys factory in Annan, one of the town's largest employers.
450 roles are set to go at the plant, as well as many more agency jobs.
Scottish Labour is now calling on the government to guarantee cash for the local area to help create work.
The Scottish Labour Leader also shared his support on Twitter.
Young's Seafood Limited confirmed they were proceeding with the closure of the site in Dumfries and Galloway at the end of May.
The announcement came after a six-week consultation into the proposal.
Workers at the factory say the site's closure will have a devastating impact on the town.