Superintendent Andre Traut said marine coastal management called the police on Tuesday afternoon to report that five vessels in the water at Buffelsbay in the Cape Nature Reserve had raised their suspicions.

Police kept a close watch on the vessels and at 1am on Wednesday policemen, including those from the diving unit, approached the vessel when it became clear that poaching was underway.

According to the department of environmental affairs, South Africa's perlemoen resource is facing a severe crisis amid escalated poaching by syndicates.

To prevent the total collapse of this marine resource and an imbalance in the area's marine life, the department has dramatically reduced quotas for the large snail like creature, which is eaten and its iridescent shell used for jewellery or to adorn decorative objects.

Traut said the crew on the vessels refused to surrender and began ramming their vessels into the police rubber duckies.

Three of the boats escaped, but the crew members of two were apprehended after police shot at their engines to force them to stop.

Thirty-three men were arrested, some who were still in the water allegedly poaching, and authorities said they found 2139 perlemoen, worth an estimated R4-million.

They will appear in court in Simonstown soon to face charges of poaching.

The two vessels, both bigger than six metres were also seized.

Another two people were arrested later on Wednesday morning, also for perlemoen poaching, but the case was unrelated to the first.

Some researchers have found a link between perlemoen poachers and drug syndicates who barter quantities of the creature for stock.