The fishermen pleaded guilty to the charges
One of the firms was fined £250,000.
The companies, Spanish-owned, but based in Milford Haven, pleaded guilty to almost 100 offences of over-fishing and catching protected species, at Haverfordwest Crown Court.
Spot checks showed that most of the boats had caught between three and four times their monthly quota, but on one occasion one of the skippers had exceeded his monkfish limit by 8000%.
The judge said the purpose of the quota system was to protect and conserve fish stocks, but it has been undermined by overfishing.
"If they can do it why can't we," said Milford Haven fishermen Martin Benwell who operates within his quota. "We're restricted this year for days at sea, which to me is stupid. I mean you've got to make a living at this haven't you."
There is increasing evidence that the quotas, which were set by the EC, are being abused. Some UK fishermen are resentful of the fact that non-UK boats have qualified for UK fishing licences.