The International Transport Workers' Federation in Ireland has said that a scheme set up to protect migrant workers on board Irish fishing vessels is "not fit for purpose."
Co-ordinator of the ITF in Ireland Ken Fleming said that the programme is not providing the necessary protection for workers and has collapsed.
The Atypical Working Scheme (for non-EEA crew) was set up in 2016 by the Government following alleged exploitation within the Irish fishing industry.
Mr Fleming said he has represented, advised and helped 117 cases relating to migrant fishermen working on Irish vessels over the past 12 months.
He added that, more recently, four African fishermen have been left stranded in Dublin after they claim they were brought here under false pretenses.
The men, from Ghana, told RTÉ News that they were promised fishing work on British trawlers but claim they were working in the wrong jurisdiction and illegally.
One of the men said they arrived in Belfast at the end of January after paying an agency in Ghana more than €1,000 to work as a fisherman in the UK.
However, one man named Joshua said they were transported all around Ireland and worked in Irish waters including off the coasts of Dublin, Waterford and Galway.
Joshua said they worked for long hours in poor conditions.
He said they were told almost a week ago that there was no fishing work for them as trawlers were being repaired and sold, and they were told to leave the boat they were working on in Howth.
Mr Fleming said: "The contracts of employment show that they would be paid no more than one thousand pounds sterling a month and that didn't specify the amount of hours."
He continued: "It didn't have any of the normal inclusions in the contract that you would expect. But moreover, they had no legal entitlement at all to be in the south of Ireland."
The men have been taken into State care.
Joshua said he had to take out a loan to reach this part of the world and he can only go back to Ghana if he has the money to pay it off.
Mr Fleming called for more robust inspections' regimes on boats and more resources to do so.
In a statement, the Department of Agriculture said that a rigorous and effective inspection system is in place.
It said that "inspectors of the Workplace Relations Commission (WRC), based on newly-acquired powers were trained and equipped, with support from a number of agencies to board vessels and carry out their own inspections."
The Seafood Development Agency, Bord Iascaigh Mhara, also said in a statement that its priority is to ensure all fishermen have proper training to stay safe at sea.
It says the organisation "does not condone the mistreatment of any workers in the sector and fully supports the Government and relevant policing agencies to provide a system that will guarantee appropriate working rights and protections for all crew members."
An investigation last year found that a quarter of Irish fishing vessels inspected by the State were caught with illegal workers on board.