MARINE experts say they are cautiously optimistic a baby humpback whale rescued in a marathon operation on the Gold Coast has survived and been reunited with his mother.

Director of Marine Sciences at Sea World Trevor Long said a mother and calf filmed by TV choppers today, a day after the rescue, could mean good news.

"Shortly after first light this morning, the Sea World rescue boat spotted a mother and calf very close to the location where the rescued calf was last seen yesterday," he said.

"A second mother and calf were also located in the vicinity and with the assistance of the Nine News helicopter, Sea World was able to obtain vision of both sets of mothers and calves."

After comparing colour markings, Mr Long ruled out the first calf.

While a positive identification for the second calf wasn't possible, it was very similar in colour to the rescued calf.

"The Sea World team is cautiously optimistic that the calf was able to reunite with its mother overnight and continue its migration," he said.

"We did hear there was an animal down at Tweed Heads that was acting in a different manner to the other whales, and we were hopeful that may have been the mother.

"That's certainly within communicating distance for these animals."

Mr Long said when it was returned to the ocean the calf was tired but in good condition, and it looked good even after becoming entangled in a shark net just offshore.

It took a Sea World team around half an hour to free the calf from the net.

"When it was fighting to get out of the shark net it had a lot of kick and a lot of fight in it, so those indicators tell us it was reasonably strong.

"And on the beach we could see it was quite robust and had wonderful responses and it did swim off reasonably OK, considering it had been on the beach for 12 hours."

Interest in the baby whale's fate has been intense, after several thousand people gathered on Surfers Paradise beach to watch the rescue.

"Australians seem to be very keen and passionate about whales," Mr Long said.

"I'm not sure if it's because we're an island nation, but whales are at the core of our marine animal values and we see that with the interest in the anti-whaling movement.

"And it's something we all should enjoy because they're beautiful animals and we're very rich to have them come past our coast."