A series of co-ordinated garda raids and searches on fishing boats, houses and factory premises were carried out earlier this morning.
The raids in Cork, Kerry, Galway and Donegal appear to be linked to ongoing investigations into allegations of overfishing of mackerel. The investigations began more than two years ago.
Overfishing has already resulted in severe cutbacks on quotas allowed by the European Union to the Irish fishing fleet for 2007 and over the next few years. These were agreed between the Government and the EU.
Fishing organisations pointed out that this action is being taken against Irish fishermen for a species of fish that is not under threat.
They say French fishermen have not been subjected to any penalties for admitted over fishing of blue-fin tuna, a very scarce species.
The French government has admitted to overfishing of €30m worth of fish in 2005 and 2006, the same period that Irish fishermen say they are being penalised for.