A rahui against taking toheroa has been placed on the northern end of Ripiro Beach to help revive critically depleted beds of the big bivalve mollusc.
The rahui applies from Maunganui Bluff to Tikitiki Stream 2km north of Mahuta Gap - a distance of about 25km - until further notice.
The ban on taking toheroa includes customary permits blamed for "open slather" harvesting. People holding permit books have been advised permits will not be accepted while the rahui is in force.
The traditional Maori environmental and cultural restriction was applied after about 20 people met at the Te Houhanga Marae in Dargaville on Saturday.
A former North Kaipara Maori Committee secretary, Maria Larsen, said she believed it was the first time a rahui had been placed on gathering toheroa on Ripiro Beach.
It was important to note customary permits applied to all kaimoana and the rahui covered only toheroa, she said. Rules needed tightening as there was an "open slather" situation with issuing permits. "Permits can be issued for hui or tangi, but these terms need defining," Ms Larsen said.
"Permits have been issued for twenty-firsts and for babies' first birthdays, but little babies don't eat toheroa. We've had people from out of town issuing permits to take 500 toheroa and we've had people on the beach taking them away in bins."
Only three people at Dargaville had authority to issue customary permits.
Ms Larsen said various possible causes of the depletion of toheroa beds, ranging from oystercatchers to agricultural fertiliser pollution, had been discussed at Saturday's hui.
"Someone said there were new rules coming out to reduce speed on the beach. Maybe the answer is not to allow any vehicles, horses or dogs on the beach because they could all contribute to the demise of toheroa?" she said. "Someone else said farm pollution flows to the beach. It's just his opinion, but I go with it. Fertiliser runoff, oil and rubbish impact on toheroa and if one dies it contaminates the whole bed."
In May, Ripiro beach veterans Des Subritzky, Joe Yakas and Robbie Sarich blamed oystercatchers for a sudden decline of big toheroa beds south of Mahuta Gap, which were well-stocked in December and are now devoid of the big bivalves.
The men claimed oystercatchers get their long beaks into the tube which toheroa extend to the surface of low-water sand and suck the mollusc from its shell.