More than £1m of taxpayers money was wasted in the decommissioning of NI trawlers, according to a report.
The aim of the scheme was to ease pressure on fish stocks
The Audit Office criticised how the Department of Agriculture ran three schemes and the way it decided which boats would be grant-aided.
The watchdog found 22 trawler owners each had their grants increased by £40,000, costing taxpayers an extra £900,000, and with "no justification".
The department said it would take full account of the recommendations.
The aim of the decommissioning programme was to ease pressure on fish stocks.
The EU established its policy in 1983 with the aim of maintaining a sustainable fisheries industry with a long-term balance between fishing activity and the conservation of fish stocks.
In 1992, however, a review found that there were too many vessels for existing stocks.
Since 1994, 100 boat owners at County Down ports shared £15m in grants to scrap their trawlers.
The report was critical of the way the department decided on which boats would be grant-aided to leave the fleet.
It said: "Contrary to its aims, the 1993-98 UK-wide decommissioning scheme appeared to decommission the least productive of applicants, as opposed to those exhibiting the highest degree of activity."
There was also a successful challenge by a boat owner, who had been denied a decommissioning grant. That cost the department £100,000.
A judicial review confirmed that six skippers who received £280,000 in decommissioning grants were not actually entitled to the money.
The report looked at the department's handling of the schemes over the period 1994 to 2005.