The Maritime Union says that a group of Ukrainian fishermen in Lyttelton are victims of the lack of regulation of the fishing industry.
The 27 crew members are currently onboard the FV Malakhov Kurgan in the port of Lyttelton where they are refusing to leave until they are paid backpay owing to them, and held a picket this morning at the gates of the port.
Maritime Union General Secretary Trevor Hanson says the 27 crew members have not been paid the correct wages for the time they have worked.
He says a further group of fishermen were sent home after accepting a lumpsum payment, but the Maritime Union has concerns about the way the situation has been handled, and the message this is giving fishing companies and charterers.
Mr Hanson says it appears that crew members have been threatened that they may be jailed when they return home unless they give up their claim.
He says the Maritime Union will support the crew and is doing what it can to resolve the situation in a positive way for them.