It's a shocking image of wanton greed - 350 blue swimmer crabs, most of them undersized, stuffed into the boot of a car.

The blatant breach of South Australian fishing laws was just one of several incidents that led to fisheries officers issuing more than $25,000 in fines during October, mostly to people caught taking undersized crabs and exceeding bag limits.

Fisheries officers from the Department of Primary Industries and Regions (PIRSA) have been patrolling popular crabbing beaches to ensure fishers are complying with the rules.

More than 1000 fishers were inspected during the past month, resulting in the issuing of more than 70 on-the-spot fines adding up to more than $25,000.

Fisheries officers also issued more than 100 written cautions and seized around 2500 illegally caught blue swimmer crabs.

Size limits apply in all South Australian waters for blue swimmer crabs, with the species considered undersized if the carapace is less than 11cm when measured from side to side at the base of the largest spines. Any undersized crabs must be immediately returned to the water.

There is also a combined blue swimmer and sand crab catch limit of 20 crabs per person.

ernal site)(external siPIRSA Director of Fisheries Operations Benn Gramola said that the blatent disregard of the law was "incredibly disappointing to say the least".

"Some of the fishers who were caught red-handed received on-the-spot fines of more than $1400," Mr Gramola said.

"This should serve as a strong reminder to those who ignore the rules that if you do the wrong thing, you will be caught and you will have to pay the price.

"Size and bag limits are in place to ensure the sustainability of popular species so everyone who wants to enjoy a day out crabbing can have a fair day’s fishing now and in the future.

"It’s the responsibility of all fishers to educate themselves about the rules and stick to them – there is clear signage at popular crabbing spots about how to measure to ensure crabs are the correct size along with information about bag and boat limits so there is no excuse for breaking the rules."

If members of the public suspect someone isn’t doing the right thing, they can report it anonymously through the 24-hour FISHWATCH hotline on 1800 065 522, or via the SA Recreational Fishing App.

For more information about fishing limits in South Australia, click here.