Talks have begun in Nelson which could decide the future of Sealord's fish processing plant there.
The company says it has to cut labour costs by $1.8 million per year, or it will shift to cheaper processing aboard factory ships.
It has already announced 180 redundancies at the factory.
The Service and Food Workers Union is resisting moves to cut conditions and freeze wages for 12 months.
Instead it is demanding a 10% pay rise over three years.
A mediator is meeting the union and company on Tuesday and Wednesday to try to broker an agreement.
