Fishing company Sealord has been accused of increasingly using foreign vessels and workers at the expense of New Zealanders.
The Service and Food Workers Union on Monday presented a 12,000-signature petition at Parliament calling for an inquiry into the fishing industry.
The union says closures and restructuring by Sealord in Dunedin and Nelson have cost 850 jobs in recent years.
Assistant national secretary Neville Donaldson says the industry is increasingly using foreign crews on foreign boats to catch fish and then sending 90% of the fish to China to be processed.
Mr Donaldson accuses the industry of profit before people.
Sealord is half owned by Aotearoa Fisheries. The Maori Party's Te Tai Tonga MP Rahui Katene says she wrote to 52 iwi involved with the company to raise her concerns about jobs and received only three responses.
Sealord says the claims are nothing more than a political stunt in an election year.