A German tourist is the first person to be caught breaking new marine reserve rules after a ranger spotted him taking mussels at a popular tourist beach at Punakaiki.
The Department of Conservation plans to step up checks, with naval and Ministry of Primary Industry patrols, and passing aircraft.
Five West Coast marine reserves were officially opened in September, covering 174sq km, at Kahurangi and Punakaiki in Buller, and Waiau-Glacier Coast, Tauparikaka and Hautai in South Westland.
DoC conservation services manager Bob Dickson, of Westport, said the tourist was apprehended near the Truman Track, on the north side of Punakaiki.
"He has received a warning," Mr Dickson said, noting the man was set to leave the country. "He was completely ignorant, a foreign visitor, we accepted that."