The traps were found in north-west area of the Christchurch's Bottle Lake Forest Park.
Christchurch City Council's Bottle Lake Forest Park ranger, Warren Hunt, said they believe the traps were laid by a member of the public who is trapping possums for their fur.
"The purpose of a leg-hold trap is to trap the possum, but not kill it which makes it easier to pluck the possum," Hunt said.
"Possum fur is a good price at the moment. They kill it and then pluck it straight away and the fur is easier to pull out."
Hunt said the people may feel they are carrying out pest control, but he said it was a public area and there was a real risk to dogs and any child who touched the trap.
Rangers are still checking the area where the traps were found everyday, but Hunt said they are fairly confident they have found them all.
Hunt said the traps themselves are not gin-traps and not illegal, but putting them in a reserve is illegal.
He said they don't know who is laying the traps, which have been handed over to police.
He said he hoped the loss of the traps will be enough of a deterrent to stop the behaviour.
The traps are generally laid on the ground at the bottom of trees.
He said the area where the traps have been found is not a high use area, but they were notified about the traps by dog walkers who had come across them.
Anyone who finds a trap in the park is advised to activate it with a stick or mud clod, and contact the council so it be removed.
Hunt said they have had no reports of any dogs or people being injured by the traps.
