Environment Agency enforcement officers and North Wales Police have staged an operation to stop illegal cockle picking on the Dee Estuary.
Officers used night vision binoculars to clampdown on illegal cocklers
The overnight clampdown on Wednesday followed reports that gangs of pickers had returned there even though the cockle beds are officially closed.
Illegal cockle picking had taken place there this week, according to reports.
Nearly 1,000 tonnes of cockles were gathered during a temporary lifting of the ban in the summer.
On Wednesday night teams of Environment Agency officers, some using night vision binoculars, were deployed along a three-mile stretch of the estuary near Holywell.
They were backed up from the air by the North Wales force helicopter.
Cocklers travelled great distances for a lifting of the ban this summer
The aim on this occasion was to deter the pickers and no arrests were made.
However, agency enforcement officers said they would return to repeat the operation on Thursday night to try to deter the gangs, who can clear several thousand pounds worth of the shell fish in one night.
In July hundreds of fisherman returned legally to the Dee Estuary when the cockle beds were opened for three days.
Around 1,000 tonnes of the shell fish were harvested.
Cocklers came from as far away as Scotland and Poland to take advantage of the relaxation.
Before that, cockle picking had been suspended for two years on the Dee Estuary because of a decline in numbers of the shellfish.
Hundreds of licences were issued to the cocklers but the environment agency confirmed at the time that there would be no further cockle fishing in the estuary this year.
The agency said it had applied to the Welsh Assembly Government and Defra for permission to introduce laws to limit the number of licences to 50 and charge a fee for the permits.