Hopes fade for abandoned baby whale trying to suckle from a yacht it thinks is its mother

The whale calf, nick-named Colin, has been going from yacht to yacht off Sydney trying to find milk for the past three days.

Mistaken identity: An orphaned whale thinks the yacht is its mother

'There's no doubt the youngster thinks the yacht is its mother,' said a spokesman for the whale-watch group, the Organisation for Rescue and Research of Cetaceans.

An attempt to lead it out to sea two days ago, following one yacht, failed when the whale returned to shallow water off Pittwater, north of the city.

Now there are growing fears the hungry calf will have to be killed to put it out of its misery. Efforts to unite it with a passing pod of migrating whales with a feeding female have failed.

Helping hand: Wildlife experts are in a race for time to try and find a surrogate mother for the baby humpback whale

New South Wales Environment Minister Verity Firth called on international experts, including Sea World in San Diego, to help in a final effort to save the infant whale.

However, although the Americans are the only people ever to successfully feed a stranded whale calf and wean it, they said nothing could be done for Colin.

The department's science officers also consulted vets from Sydney's Taronga Zoo on options to feed the struggling infant with baby formula until a rescue strategy could be devised. Again that possibility has been ruled out.

The calf swims around  the Pittwater. Attempts to return it out to sea have failed

Ms Firth said hope had not been lost and another attempt would be made to tow the calf back out to sea in the hope it would be adopted by a passing pod.

'We haven't given up. The whale is still healthy. We will try again to encourage it back out to deeper water,' she said.

It is believe the humpback calf was either abandoned by its mother or orphaned during the annual whale migration north from the Antarctic up the east coast of Australia.

Mother ship: Officials are puzzled to why the calf lost its mother

Humpbacks breed every one to three years. They have a gestation period lasting up to 12 months and a life expectancy of up to 80 years.