Roman Butchaski was on a solo fishing trip in Queensland’s remote Cape York Peninsula when he failed to return to his camping ground.
An avid angler, Mr Butchaski – known as Butch – is a former host of Sydney radio station 2GB’s fishing show.
A major air and land search has been launched after he was last seen on Sunday.
More cops were drafted in to help the search efforts on Tuesday and rescue helicopters and ground crews have been combing the region for three days.
Some of Mr Butchaski’s belongings have been found near a river – including his fishing rod.
His former co-host Gavin Pitchford told 2GB that his friend regularly visited the spot on the Olive River – about 370 miles north of Cairns.
“I’m devastated. Butchy walks the banks up there regularly. He’s been fishing there forever,” he said in a statement read out on air.
The remote Olive River runs for 42 miles at the very top of Australia‘s northern mainland.
Mr Pitchford fears Mr Butchaski, who has diabetes, may have suffered a medical episode.
Police said Mr Butchaski’s car was found at the river.
Local reporter Harry Clark told 2GB host Ben Fordham: “He borrowed a side by side buggy from a friend and travelled about an hour to to go fishing along the banks of the the Olive River.
“All that they’ve found of Butch is that vehicle with a few personal effects such as a fishing rod that was found on Sunday afternoon and he hasn’t been seen since.
“It’s on Cape York and the Olive River is a tidal saltwater river – and like all waterways in that area, they’re known crocodile habitat.
“That’s certainly one of the things that search crews are taking into consideration as they as they look for Butch.”
Queensland Police Senior Sgt Duane Amos said the region is a well-known crocodile hotspot – but added that Mr Butchaski is familiar with the area.
Sgt Amos said the former radio host “was well-prepared for a normal expedition that he has undertaken before”.
Although crocodiles attacks in Australia’s north are uncommon, there have been several this year.
The remains of fisherman Kevin Darmody, 65, were found inside a 4.1-metre crocodile on the Kennedy River – a crocodile hotspot.
Cops said it was a “tragic ending” to a two-day search as Mr Darmody became only the 13th person killed in a crocodile attack since records began in Queensland in 1985.