Boaties are sneaking dogs onto Rangitoto and Motutapu Islands, the Department of Conservation (DoC) says.
However, DoC Auckland Inner Islands operations manager Keith Gell said they did find dog prints.
"People sneak them on, I'll be honest about that.
"They will spot a ranger and they will just wait until the ranger goes and they will go to a discrete bay [and] take the dog off the boat to exercise it or for it to do its business."
Mr Gell said the paw prints were definitely not from dogs used during the cat search.
Dogs are not allowed on Hauraki Gulf island reserves.
Rangitoto and Motutapu have been free of predators and pests since 2011.