Jian Lin, 28, Jiannei Lin, 26, and Xiaokang Zheng, 23, all from Auburn, have been fined $5000 and ordered to pay costs of more than $5800 after being caught with more than 270 blue swimmer crabs in Culburra Beach in February last year.

None of the men appeared in Nowra Local Court on Tuesday in a case brought by the NSW Department of Industry.

The court was told after receiving a tip off about illegal fishing activities at Lake Wollumboola at the seaside village, NSW Fisheries officers went to the location about 9.30pm on February 5, 2016 and found the trio with 273 blue swimmer crabs, of which 270 were undersized.

The crabs ranged in size from four centimetres to 5.8cm The minimum legal size to be able to take a blue swimmer crab is 6cm.

It is an offence to possess more than 20 blue swimmer crabs and there is also a limit of only 10 of the species allowed to be taken per person, per day.

As officers arrived at the carpark near the lake they saw two cars. Then the trio arrived with five yellow containers carrying the crabs.

Two other people were also located in the waiting cars.

Court papers said Jian was the only person in the group who spoke English and he told officers they had caught the crabs.

Fisheries officers seized the illegal catch and later released the crabs into Broughton Creek.

Jian Lin was charged with possessing prohibited sized fish, while Jiannei Lin and Xiaokang Zheng were both charged with possessing prohibited sized fish and possessing more than the prohibited limit.

Magistrate Gabriel Fleming heard the case in their absence and convicting all three men.

She fined Jian Lin $1000 and ordered he pay costs of $1176 to the Department of Industry, while Jiannei Lin and Xiaokang Zheng were both fined $2000 and ordered to pay $2352 in costs.