Why are toheroa disappearing again from Northland's west coast Ripiro Beach? Some beach watchers tell reporter Mike Barrington who they think the culprits are.

Millions of toheroa have disappeared from Ripiro Beach and local men with lifetimes of west coast experience believe oystercatchers are the culprits.

Beach veterans Des Subritzky, Joe Yakas and Robbie Sarich blame the native oystercatchers for the 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 claim 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.


"It's a national disaster. We're protecting toheroa from human predators, but these birds are eating the lot," Mr Subritzky said, predicting the oystercatchers could have to be culled.

On Tuesday, the trio took the Northern Advocate to see some of the 16 major toheroa beds on 25km of Ripiro Beach between Tikitiki and Sandy Slide which MessrsYakas and Sarich had surveyed in December.

Only small, empty shells on the surface of the sand and searching oystercatchers marked the spots where shellfish had been thriving about 4km south of Glinks Gully.

Beds at Glinks Gully, Te Kopuru Rock and Chadwick's Stream had similarly lost all their toheroa since December. The three men forecast that shellfish at Oturei Stream would be the next to go as oystercatchers moved north up the beach.

They said more than 4000 of the birds had been counted at Kelly's Bay on the Pouto Penninsula.

However, Mr Yakas was puzzled there were not lots of big empty toheroa shells on the beach.

Mr Subritzky said shifting sand must have covered the shells, but Mr Yakas pondered over whether the toheroa had moved out to deeper water.

Meanwhile, two seabird experts - Hugh Robertson, from the Department of Conservation in Wellington, and John Dowding, a Christchurch consultant - expressed doubts about oystercatchers, weighing up to 725g, being capable of extracting an adult toheroa from the sand, let alone opening it to feed.

The birds are variable oystercatchers, which specialise in eating bivalves, pulling pipi, mussels, cockles, tuatua and small toheroa out of the sand and hammering them open with their bills or forcing their bills between the shells.

Both experts also claimed variable oystercatchers were relatively rare, with less than 4000 of them in the country.

That got Mahuta Rd commercial fisherman Dylan Chamberlain scoffing. He said he had seen the birds sucking up adult toheroa, leaving empty shells in the sand. He suggested the experts go to Kelly's Bay and see the thousands of oystercatchers which had assembled there in recent years.