A freshwater crocodile has been found in the Murray River near the New South Wales-Victoria border, thousands of kilometres south of home.

Key points: Brent Lodge pulled the dead freshwater crocodile out of the Murray River near the NSW-Victoria border

Brent Lodge pulled the dead freshwater crocodile out of the Murray River near the NSW-Victoria border It had a hook in its mouth and had been partly skinned

It had a hook in its mouth and had been partly skinned Experts say it is extremely unusual to find a croc in such cold waters so far south

Gold Coast electrician Brent Lodge was back home visiting friends and family in Barham, in south-western New South Wales, on the Victorian border, and went fishing on the Murray River with his father on Sunday afternoon.

He said he was out fishing with his "old man" and was "just blown away" by the amount of rubbish in the river.

"So I thought, before I fly back to the Gold Coast, I'll shoot down in the boat and try to pick up as much as I can," he said in an Instagram story.

"It astounds me, it really does, what you find in here.

"It's a bit of an eerie place, the Murray, and you won't believe what I've just found: I've just found a freshwater crocodile hanging off a snag."

The dead crocodile had a hook in its mouth, Mr Lodge said. ( Instagram: @lodgie828 )

Mr Lodge filmed the crocodile, which he said was about 1.8 metres long, swirling past his boat surrounded by rubbish.

He said at first he thought it was a log, or "a big dead Murray cod" before realising it was a freshwater crocodile when he picked it up by the tail and hauled it in.

"Number one, they don't even belong in the Murray River, as far as I know; I've never seen anything like it," he said.

"It's got a hook in its mouth, it actually looks like it's been skinned, so I don't know what's going on there."

Mr Lodge said he left the crocodile on the riverbank.

"A lot of people are saying, 'why'd you leave it on the bank?' Not sure what you want me to do with a dead crocodile, it stunk," he said in a later video in response to comments.

"It's an unfortunate circumstance and that's just the way it is."

He denied having anything to do with how the crocodile got into the river system.

"Where the f*** am I getting a crocodile from?" Mr Lodge said.

"Did I skin the crocodile? … I don't even know how to fillet a fish."

Freshwater and saltwater crocodiles — both of which can live in fresh or saltwater — are protected species.

Alive or dead, crocodiles, their eggs, or parts of crocodiles cannot be sold, traded or possessed without a permit.

In some states, killing or harming a crocodile carries a fine of up to $225,000 or up to two years in prison.

Croc not escaped from local parks

Rebecca Surian, operations manager of the nearby Altina Wildlife Park, said the crocodile had not come from their zoo.

"We are not missing any of ours so don't point the finger at Altina, all of our crocodiles are here and accounted for," she said.

"Maybe someone may have stolen a crocodile, or thought it'd be fun to have one in a bathtub for a little while and got sick of it and let it go," she said.

"That poor crocodile had to possibly live through being where it's too cold to survive, it may have died in the river, it might have been stolen, or possibly euthanised and skun for someone's pleasure, which is quite disturbing."

Nearby wildlife parks said the crocodile wasn't one of theirs. ( ABC Open contributor wildmanphoto )

Croc 'skinned by amateur'

Northern Territory crocodile expert Graham Webb, from Crocodylus Park, said he was puzzled by the discovery, as the water temperature of the Murray was too cold for freshwater crocs.

Crocodiles' preferred body temperature is 30 to 33 degrees Celsius, which they manage using water, sun and shade.

Their natural habitat is across the tropical north in Western Australia, the Northern Territory, and Queensland.

"It's definitely been skinned by an amateur," Dr Webb said.

"It's not been professionally skinned … it's taken off by someone used to skinning a fox or a kangaroo."

Crocodile biologist Graham Webb at Crocodylus Park in Berrimah, Darwin. ( ABC News: Steven Schubert )

"It just puzzles me completely, because the fact it's got a hook in its mouth means the guy may have strung it up to take the skin off it, but he might have caught it when fishing — if he had a decent sized bait on it, freshies sometimes take that and get caught.

"If he caught it by accident and it was alive, he really wouldn't have known what to do, but if it had tangled up as they do in some of the stumps and logs and things in the water, it could have easily drowned."

He said there was "zero value" in a freshwater crocodile's skin.

"If they're skinning a crocodile for products — not that freshies are any good for products — you'd skin it the other way, from the back down," Dr Webb said.

"Normally you'd try to get the belly skin for product, this is something for interest or display."

He said the croc looked as though it was in good condition, and wasn't emaciated.

"It's probably fairly old, inasmuch as a 6-foot freshy usually takes a long time to get to 6 foot; if it was incredibly well fed it might take 20 years, but in the wild, often a 6-foot freshy is quite old," he said.

He said the croc's death wasn't a conservation issue, as there were plenty of freshwater crocs across the country.

Dr Webb said locals didn't need to worry about crocs colonising the Murray — "unless they catch another one!"