The future of Port Lincoln Tuna Processors and its workforce of about 136 looks uncertain due to a lack of major long term production contracts on the horizon.
The company issued a statement that it was in consultation with employees regarding significant structural changes at its Port Lincoln food processing facilities from mid-June.
This followed the company receiving news that a major customer would not renew their production contract, on top of a lack of new opportunities or support for operations.
Port Lincoln Tuna Processors managing director Mario Valcic said the company had been a respected member of the Port Lincoln business community since 1973.
"We have worked very hard to sustain our operations amid challenging business conditions in regional South Australia and COVID-19 upheavals," he said.
"It is saddening to have to face the present reality.
"I would like to extend my sincere thanks to all staff and suppliers of PLTP for their support and loyalty."
The business opened in 1973 to provide facilities for local fishermen to process, freeze and export bluefin tuna, however it has not processed tuna since the canning contract for John West moved offshore in 2010.
This brought an end to Australia's long history of canning tuna.
However the company had diversified to process different foods such as soups, gravies, custards and baby food.
Port Lincoln Chamber of Commerce and Tourism chairperson Jack Ritchie said there was some concern for the company and the workers and the impact downsizing or closure would have on Port Lincoln.
He said the chamber would do what it could to connect workers to services to help reduce the impact, and there were many vacancies available within Port Lincoln.
"We have a large number of job vacancies so if there was a downsizing or closure, there are jobs available in Port Lincoln," he said.
"The best scenario would be for it to continue operating."
Mr Ritchie said Port Lincoln Tuna Processors' ability to innovate and continue as one of the largest employers in Port Lincoln while incorporating other food processing lines had been incredible.
Regional Development Australia Eyre Peninsula had also expressed desire to support processor staff.
Chief executive officer Dion Dorward said the organisation would be keen to work with the processor owners to look at long term options, such as a return to processing seafood, however the important thing was to ensure the support for workers.
"The loss of 136 jobs at any time is a real concern and the (Port Lincoln) Tuna Processors has been a tremendous asset to the region in terms of jobs and economics," he said.
"We're confident many of the people working out there can find alternative employment.
"We'll certainly do our best to ensure the workforce is supported."