Immediate action is needed to stop people from driving vehicles near the mouth of the Waikanae River area, north of Wellington, a concerned resident believes.
Dr John Robinson, from Waikanae, has written to Minister of Conservation Eugenie Sage, saying the sandspit was a national treasure environmentally and recreationally but vehicles were often driven and parked in the area when they weren't allowed.
"These are most numerous, and do the most damage to the ecosystem, during the whitebaiting season," he wrote.
Dr Robinson said he was advised by the Department of Conservation that vehicles were breaching bylaws by travelling along the beach into the Waikanae Estuary Scientific Reserve, which in turn "can damage shellfish beds, endanger wildlife such as nesting birds and, of course, people".
And while the local council issues permits for people wanting to drive on the beach for whitebaiting, it was "absurd since the whitebaiting takes place along the river in the scientific reserve, which is excluded in the permits".