Young's Seafood, the UK's largest seafood processor, will close its Marsden Road site in Grimsby in England.
Production at the site is being scaled back before ceasing entirely in late October.
A consultation process has since been ongoing with staff and representatives.
"It is with regret that we have been unable to find a viable solution to maintain future production at the site," Young’s Seafood said in a statement.
"The closure has been necessary following changes in future demands for products produced at the site, and we explored a number of options to maintain operations and to protect roles," Young’s Seafood said.
The remaining whitefish processing undertaken by Sofina Foods Europe, which owns Young's, will move to the Humberstone Road site in Grimsby, and smoked seafood processing to its Fraserburgh site in Scotland.
During the coming months, a number of new roles will be created at the Humberstone Road and Fraserburgh sites, the company said.
Young's, which was founded in 1805, has been based in Grimsby for more than 50 years. The firm has two factories in Grimsby and employs 1,700 people, making it the town's biggest private employer.
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