The seafood company last week announced a change to its processing sites and signalled possible job losses in Southland.
Its Bluff factory would focus on premium salmon production, while whitefish processing would be carried out at the Timaru site.
Etu organiser Anna Huffstutler said the petition, after a couple of hours of being online, had attracted more than 150 signatures.
''It has been overwhelming the support of the community.''
A meeting was held with the workers yesterday to update their situation and support them.
Their mood was still pretty low, Ms Huffstutler said
''They still are in shock and grieving. They are starting to think about what they are going to do.''
The union had asked for an extension of the consultation process, which is scheduled to end tomorrow. However, it was still waiting for an official answer.
''We need more information and a better understanding of some points.''
She calculated the job cuts would mean $2million lost in wages for the Bluff community.
''This is a huge amount for a small community such as Bluff.''
Sanford chief executive Volker Kuntzsch said last week the company's move was about creating three ''centres of excellence'' across the South Island, and the change would mean some job losses in Bluff.
The company would not know how many jobs would be cut until the consultation process ended.
''Our focus is finding a solution for every single person,'' he said.
