No arrests are planned at this stage of the investigation into illegal activity in the fishing industry, according to the man heading the inquiry, Det Supt John O'Mahony.
A large amount of documentation and a number of computers were seized in raids on processing factories, company offices, private homes, boats and agents' offices in Killybegs.
The Garda team will have to examine and assess this information in order to progress this complex inquiry.
Rossaveal Port in Co Galway was also targeted and searches were conducted at three houses in the Castletownbere area of Co Cork earlier today.
Gardaí were led by a team from the National Fraud Investigation division in Dublin, and backed by divisions from Sligo-Leitrim, Cavan-Monaghan and Donegal.
The raid at Killybegs is thought to be connected to allegations of illegal activity by fishermen at the port made by local fisherman Pat Cannon.
Gardaí are examining claims including fraud and breaches of fishing quotas.
When the allegations were made by Mr Cannon the Killybegs Fishermen's Organisation said it had nothing to hide and no evidence of illegal activity would be found.
