Professional Northern Territory crocodile catcher Roger Matthews is well prepared.

He keeps two firearms in his boat when cruising Top End billabongs in search of crocodiles that are killing cattle.

His hand gun, a .45 Colt, is for protection while the rifle is for "dispatching" crocodiles, but his Bowie knife is never far away.

"I've donked a couple of crocs on the head with it, but more so, once they've been tied up and dispatched, I'll cut the vertebrae with it so it bleeds them and you know that they're dead," he said.

"I only use a small calibre gun when I'm dispatching a crocodile, a 22 or a 22 magnum.

"I don't shoot in the head at all. I come back along the spinal cord and I shoot into it. It's pretty instant."

Mr Matthews said he fires two shots.

"I always give it the gentleman's double to be sure."

Mr Matthews said his 30cm knife has saved his life more than once.

"I've had it 31 years and I've had some pretty wild times.

"It's saved me a few times from large vertebrate wildlife."

He chuckles as he responds to a question about how he used the knife in those situations.

"A bit like a Singer sewing machine," he said.

"I've had a pig come and have a go at me.

"He was trying to get me with its tusks and I was trying to get it with the knife.

"I won. It's very sharp," he grins.

"I love my knife."

When catching crocodiles on Annaburroo Station, 100km from Darwin, Mr Matthews sets up camp about 30 metres from a billabong on the station, sleeping with a firearm on an elevated platform.

"The crew that was operating out here before us had a 4.4-metre crocodile come in the camp.

"I tell people not to muck around when they're waking me up."