Hundreds of fishermen have taken advantage of the opening of the Dee Estuary beds for a three-day period.
Hundreds of livelihoods depend on cockle-picking
The Environment Agency issued more than 600 licences for cocklers at Thurstaston and Mostyn Bank in north Wales.
West Kirby in Wirral, the richest of the beds this year, has not opened due to the presence of Diarrhetic Shellfish Poisoning (DSP).
At first light on Tuesday, the fisherman turned out in their hundreds eager not to waste a minute of time as the Dee estuary beds were reopened.
Cockle-pickers have called for the beds to be open for longer periods under more strict regulation because they are worth a great deal to the economy of the area.
Colin MacDonald who owns a cockle production company in Holywell, Flintshire said three days is not enough to harvest the number of cockles in the River Dee.
"I've got a cockle processing plant that's ready to go if need be but you can't run a business on three days of fishing," he said.
"The price of cockles is so high it could be a bonanza year."
But the Environment Agency says it must first ensure that cockle levels are high enough to allow harvesting without causing a threat to future stock levels.
If the tests show numbers are higher and the cockles are mature enough they are hoping to reopen the beds to the fisherman for a longer period at the end of August.
Elsewhere in the UK, there have been complaints that gangs were coming in from as far afield as Malaya, China and Europe to pillage the cockle beds.
In Morecambe, 37 suspected illegal immigrants have were arrested for picking
cockles from a beach in the Chatsworth Road area.