Queensland's Department of Primary Industries (DPI) is concerned about a whale that may have become entangled in a shark net off the Gold Coast.

DPI shark control program manager Tony Ham said today the whale, which could be a humpback, may have become entangled and then broke away with the net still attached.

A shark net 186 metres long by six metres deep was discovered missing off Currumbin Beach on Saturday.

Mr Ham said whales occasionally became entangled in the nets despite acoustic markers designed to help direct the mammals around them.

"It's rare for a whale to break away and swim with the net," he said.

"The last time that happened was in 2003. A whale was found two or three days after [getting caught] around Byron Bay.

"The net was still attached and our marine-animal release team cut it free."

Mr Ham said authorities believed this was a similar situation, and had sent a helicopter to Byron Bay on the weekend to scout for a whale with a shark net.

"We didn't find anything," he said.

"We are certainly concerned. There would be some injury to the animal and if the net were to be attached to the whale in the long term it would be detrimental.

"It would be having an impact on its ability to swim."

Authorities hope the net will somehow dislodge, or the whale will swim closer to shore for easy spotting.

AAP