Otakou Runanga is concerned the find of an extremely rare pre-European waka outrigger beside the Papanui inlet could put the site at risk from people stealing artefacts.
Manager Hoani Langsbury says the outrigger, only the third found in this country, was uncovered in an official archaeological excavation.
But he says any remaining taonga Maori may now be at risk.
"Within the last year we've had a site identified that had both cultural and European archaeological material in it and as soon as media made the local community aware of the find, the material disappeared within 24 hours,"he told Waatea News
"People just came through and stripped the site bare."
Mr Langsbury says runanga representatives will patrol the area and won't hesitate to take action against scavengers who try to steal artefacts.