The man rescued the stricken animal on Tuesday morning as officials took more than two hours to respond.

"I saw the whale and I thought, 'That is pretty cool'. Then I saw he was in the net and I thought, 'That is not cool'," the rescuer, who asked not to be named, told reporters.

He took off his shirt and donned swimming fins before diving into waters off Burleigh Heads, using his knife to free the baby whale's pectoral fin from the net which was cutting into its flesh.

"He was about eight to nine metres deep. Because of the adrenalin my heart was just pumping," he said, describing his repeated resurfacing.

It's unknown how long the calf - believed to be a humpback - had been trapped.

It was spotted about 7am by a drone operator, and a crew from the Department of Agriculture and Fisheries arrived at the scene at 9.45am.

However, the man had already rescued the whale and sent it on its way, drawing a cheer from a crowd of onlookers who had gathered on the cliffs above the water.

While the rescuer is being hailed a hero on social media, he now risks a fine of up to $26,900 for interfering with shark control nets.

He said staff from Queensland Fisheries intercepted him as he came to shore.

"Yeah I'm in trouble. I wasn't going out there to see whales. It was an expensive day but whatever ... you pay the price sometimes. I didn't think about what the fine was," he said.

Queensland Fisheries has confirmed it is investigating but says no fine has yet been issued.

Fisheries Minister Mark Furner said the rescue was incredibly risky.

"It is dangerous equipment. We have unfortunately seen the loss of life when people have themselves become entangled in this equipment," he said.

"It will be up to the department to consider whether this gentleman will be prosecuted."

Sea Shepherd campaigner Jonathan Clark said the man's actions were brave.

The conservation group is calling on the government to remove shark nets as the whales head north for their annual migration to warmer waters.

"Their removal during the whale migration season would be a good start and could be accompanied by the serious proving of other technologies such as drones," Mr Clark said.

The state government's shark control program has been mired in controversy for years.

Aspects of the program were successfully challenged in court last year by the Humane Society, which argued catching and killing sharks did not reduce the risk of an unprovoked attack.

However, a number of shark nets and drumlines were reintroduced along the Queensland coastline in a reported attempt to stem a drop in tourism numbers following a string of attacks, one of which was fatal.

The amended program encourages the release of most sharks but allows state contractors to kill sharks if necessary.

Australian Associated Press