A total of 14 Irish and EU-registered fishing boats were detained by marine inspectors in the first quarter of the year for alleged breaches of fishing regulations.
The Sea Fisheries Protection Authority (SFPA) said there were also some 28 cases of the alleged illegal landing of fish.
The SFPA conducted inspections in co-operation with the Irish Naval Service and detained the ships at various locations in Wexford, Cork, Waterford and Dublin.
Another 14 vessels were issued with written warnings.
SFPA chairman Peter Whelan said the seafood industry makes a vital contribution to the economy and stock conservation and fisheries monitoring were essential elements of a thriving fishing and seafood sector.
“It is unfortunate that this valuable and declining natural resource continues to be abused by a minority of fishermen. Overall, the work of the SFPA supports the livelihood of law-abiding fishermen and ensures that rogue operators do not undermine their future existence,” he said.
In one case, the Ronan Rosswas detained at Ringaskiddy on suspicion of illegally fishing herring. The master was cautioned and later charged by gardaí.
Written warnings were also issued to vessels off the south west coast for alleged infringements, including failure to have fishing licences and vessel registration documents, as well as failure to comply with regulations to prevent the accidental catching of dolphins.