Another group of three men, spotted diving from a boat at Black Head at Gerroa, was found to have 23 Eastern Rock Lobsters - 17 of which were concealed in an underfloor compartment.

The bag limit for these crayfish is two per person, and size limits are also in place.

The cases have come to light after the men, aged 36, 23 and 21, were successfully prosecuted in December, with the details being revealed by Minister for Agriculture Adam Marshall.

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"There is a two bag limit for Eastern Rock Lobsters and size limits are also in place for a reason - to ensure our fishing resources remain sustainable into the future," Mr Marshall said.

"These three men tried to take more than their fair share and they've paid the price.

"This is a harsh reminder that crime doesn't pay - the trio faced Kiama Court, pleaded guilty, and now instead of feasting on scrumptious seafood, they each have to fork out $2000."

Mr Marshall said two of the 23 rock lobsters were undersized, so the boat, motor, trailer and dive gear were all seized. The bust happened in June last year.

It was estimated the crayfish could have fetched $5000 if sold - which is why specialty shellfish are targeted for disposal on the black market.

Mr Marshall also said that in a separate court date last December, a man was busted for an incident which happened in 2016.

He had been spotted by Fisheries officers who had him under covert surveillance.

They followed him to the car park of a hotel in Gerringong and found him selling six rock lobsters.

He was fined $1350 after being convicted last December.

Information from the NSW Department of Primary Industries (DPI) said Bass Point had emerged as the location for the most frequent fines for illegal fishing in the region.

Supervising Fisheries Officer for the Greater Metropolitan Zone Joel Cox said this was because of its popularity for recreational fishing.

He said Windang and Port Kembla were also hot spots.

Fisheries said 563 offences had been recorded in the Illawarra since October last year, with more than 1600 checks on fishers.

This includes both recreational and commercial fishers. Some fishers have had more than one offence.

The majority of people received a caution - there were 377 cautions, 162 penalty notices and 20 prosecutions.

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