Four-metre croc euthanised after boy's body found

A huge crocodile believed to be responsible for a fatal attack on a 16-year-old boy in the Torres Strait has been euthanised.

Wildlife officers began a search for the reptile after the teenager's body was found on a remote far north Queensland island on Thursday afternoon.

The teenager and a 13-year-old boy had attempted to swim ashore when their dinghy broke down 500m off Saibai Island, 900km north of Cairns.

The boys had almost made it to shore and were in waist deep water when the 16-year-old suddenly vanished.

The shaken 13-year-old made it to land and raised the alarm, sparking an extensive sea, land and air search.

The 16-year-old's body was found in mangroves on the island 12 hours later with injuries consistent with an attack from a crocodile at least 3.5m in size.

After the local community requested the animal be removed, wildlife officers located a four-metre croc the next day near the area where they believed the boy was killed.

"The animal displayed parading behaviour such as raising its head as it swam, which is consistent with it being the target animal," a Department of Environment, Science and Innovation statement said.

"The crocodile was humanely euthanised early on April 20 and disposed of at sea, in keeping with the wishes of the Saibai Island community."

DESI said community members had expressed their appreciation for the rapid response.

"The Department of Environment, Science and Innovation expresses its sincere condolences to the friends, family and community on Saibai Island."

The 16-year-old's mother has set up a GoFundMe page which had raised more than $14,000 by late Monday.

The mother-of-nine said her beloved son would be remembered as a "very humble, kind-hearted young lad".

The 16-year-old was also a "very athletic person" who enjoyed playing rugby league.

"Always smiling and eager to help anyone who crossed his path," the mother wrote on the GoFundMe page.

"I am humbly seeking assistance...to help my children and I ...through this difficult time.

"Any and all contributions will be greatly appreciated. My family and I humbly thank you all."