He said the bull was moving throughout the reserve and that DoC was having difficulty tracking its location. No one has yet come forward to claim ownership of the animal.
Mr Carlton said the owner has 14 days to contact DoC or the bull would be destroyed.
Charolais Breeders New Zealand Vice President Simon Collin said it was amazing no one knew who the animal belonged to.
"They will eventually find out who the owner is when they catch the bull dead or alive, the tags don't lie."
Mr Collin suggested a local farmer should get some cattle in the reserve to team up with the bull and muster him back home.
The local farming community had been alerted to watch out for the bull. However, the process for trespassing illegal stock has been started and this will allow the department to deal with the animal if no one claims it, Mr Carlton said.
Anyone with information should contact the Department of Conservation urgently on 06-8343-111.