Cornish cockle enthusiasts have been issued with a warning as they take part in the annual Good Friday "trigging" event.
The Cornish tradition of "trigging" takes place every Good Friday
They are being urged to measure their cockles to ensure they comply with new size bylaws introduced by the Environment Agency.
Hundreds of people arrive at the Helford Estuary each year armed with buckets and rakes.
Trigging, which involves families hand-harvesting cockles on the mudflats at low tide, is thought to date back hundreds of years.
Local people are very supportive and recognise the need to protect Cornwall's cockles
James Burke, Environment Agency
A series of bylaws have been introduced to protect cockles in Cornish estuaries after a team of commercial boats dredged the Camel Estuary in 1996 using powerful suction equipment, almost wiping out the cockle population.
The Environment Agency says trigging will not hurt stocks, as long as people do not collect shellfish any smaller than the minimum legal size of 20mm, or a 20p coin.
It has printed and distributed a number of beer mats to local pubs, with messages like "Have You Measured Your Cockles?" and "Keep Cornish Cockles Alive Alive-O!".
Environment Agency spokesman James Burke said: "Local people are very supportive and recognise the need to protect Cornwall's cockles.
"When we developed the bylaws, we were keen not to impact on traditional cockling methods."
The new bylaws, approved by the Department of Environment, Food and Rural Affairs, will protect stocks on the Camel, Helford, Fal, Fowey and Looe estuaries, where only hand-harvesting is allowed.