A stoat has made its way onto a pest free island in Auckland

Department of Conservation rangers are working to catch the stoat on Motutapu Island in the Hauraki Gulf.

Operations Manager Katharine Lane says it's disappointing and a timely reminder for people to make sure their boats are pest free before heading out.

She says if pests get onto any of the 47 islands in the gulf, it could have devastating effects on the native wildlife.