Wildlife officers have killed a 4.2-metre crocodile that attacked a man and ate his dog in Far North Queensland.

Alister MacPhee is recovering in a stable condition at Cairns Hospital after the attack at a Bloomfield boat ramp, about 50 kilometres south of Cooktown, on Wednesday evening.

Mr MacPhee has declined interviews but released a statement through Cairns Hospital thanking emergency services and staff at Cairns Hospital "for looking after me".

He also thanked his dog, "Magic Molly", "who was always by my side".

"I have, unfortunately, learned the hard way," Mr MacPhee said.

Magic Molly's remains found

Department of Environment and Science incident controller Michael Joyce said officers conducted found the remains of the dog during a necropsy on the crocodile, which was shot late Thursday.

"Molly was inside that crocodile," he said.

Mr Joyce said the Northern Territory man had "come from croc country to croc country" and should have been aware of the risks.

"I would've expected him to know better," he said.

Video footage surfaced on social media appearing to show a man wade into the Bloomfield River at the Ayton boat ramp with his dog.

The crocodile attacked once he was in knee-deep water.

The Department of Environment and Science said the man had declined to speak to them about the incident.

A spokesman for the Department of Agriculture and Fisheries said Biosecurity Queensland had not received any complaints about the incident and was not investigating it.

'Disappointing for all of us'

The boat ramp is located in a zone where wildlife officers remove crocodiles that are a danger to the community.

The crocodile responsible for the attack was found about 200 metres from the boat ramp.

"If you go into croc territory and try to go swimming in somewhere like the Bloomfield, and the crocodile then associates humans with a food source, that's going to change that crocodile's behaviour," Mr Joyce said.

Wildlife officers worked with traditional owners and police to respond to the incident.

Mr Joyce said the need to shoot the crocodile was "really disappointing for all of us".

He said wildlife officers were extensively trained to ensure the reptile was euthanised "as [humanely] as possible".

"This is the easiest and most direct manner in which to make sure the crocodile we take out of the system is the crocodile who did actually take Molly," Mr Joyce said.

The crocodile is unlikely to be the largest in the Bloomfield system.

Cook Shire Council Mayor Peter Scott said the 37-year-old man's behaviour was disappointing given the prominence of warning signs.

"He was terribly lucky and look, I feel so sorry for him that he's lost his dog, who may well be his best mate, and he was visibly upset in the video too about what had just happened," he said.