A cat crackdown will be phased in around Tasmania over 12 months to give pet owners time to adjust.
New laws tabled in State Parliament will allow the trapping and killing of cats found on property more than a kilometre away from the owner's home.
Cats within that distance will have to be returned or taken to a shelter.
Conservation Trust Director Peter McGlone is worried people will choose to kill the cat rather than send the animal back to their owners.
"I was talking to people this morning, who said if you trap an owned cat, you just kill it. That's not the solution, the solution is that the owner of the cat needs to take responsibility of that cat, not the person who is trapping it and that's where this government's gone wrong. They don't want to respond to the issue that owners need to take responsibility for their cats."
He says the laws don't go far enough and is urging the government to introduce fines for owners who continue to let their cats stray.
"If you're out there trapping cats in your local reserve or on your farmland and you find an owned cat, then to you have to take it back to the owner, and if it gets out again, you take it back, again and again and again and there's nothing whatsoever you can do about that, now that is the problem. There should be fines for the owners to stop that," he added.