Five Irish-registered fishing vessels were detained in Dublin and Cork by inspectors last month, and six other vessels were issued with written warnings for alleged breaches of fisheries laws.
The Sea Fisheries Protection Authority (SFPA) in co-operation with the Irish Naval Service inspected Irish and other EU member state fishing vessels during February.
In one case, the Irish-registered boat Joseph Swas detained on the south coast for allegedly under-recording its catch and exceeding the monthly quota of monkfish.
Another Irish-registered vessel, Western Dawnwas held at Ballycotton, Co Cork, on Thursday 21st February, for the alleged failure to comply with port landing requirements having fished for cod.
The Naval Service also detained The Boy Connoron the south coast for alleged breaches of the law in relation to its monkfish catch.
Files have been forwarded to the Attorney General in all cases.
Chairman of the SFPA Peter Whelan said that although there was a genuine attempt on the part of many fishermen to comply with the regulations there was "much room for improvement".
"It is a shame that this valuable and declining natural resource continues to be abused by a minority of fishermen. . . . The sustainable and legal exploitation of fish will ensure a future for the fishing industry in Ireland," he said.