In the end, not even a whale whisperer could save Colin, a baby humpback that has spent the week nuzzling up to yachts in a Sydney waterway in a desperate search for its mother.

The plight of the two-week-old calf, which turned out to be female, captivated the world after it was discovered bonding with a boat in Pittwater harbour, trying to suckle from the hull.

Despite an international call for help, an offer of assistance from the Army and a last-minute attempt at spiritual healing by an Aboriginal whale whisperer, nothing could save Colin. It was humanely put down by vets early yesterday.

Officials from the National Parks and Wildlife Service had tried unsuccessfully to lure the mammal to deeper waters, in the hope that it would be adopted by one of the whale pods travelling along Australia’s east coast as part of their annual northern migration.

Experts had tried to work out how to feed Colin by hand but, because of her size and intake — baby whales suckle for 11 months, consuming 230 litres (405 pints) of high-fat milk every day and gaining about 900 grams (2lb) a day — it was deemed to be an impossible task.

Whale experts from Sea World in Queensland flew to Sydney to assess Colin’s situation but, with specialists from the National Parks and Wildlife Service and Taronga Zoo in Sydney, it was decided that the whale was too weak to survive after not eating for five days.

They decided that the most humane option was for it to be put down.

A veterinarian’s report and blood tests disclosed that the two-tonne calf had only hours to live. It was suffering from shark-bite wounds and breathing difficulties and was having trouble swimming.

Dozens of members of the public gathered at dawn at The Basin, in the picturesque Pittwater waterway just north of Sydney, to watch Colin’s final hours.

Amid emotional scenes from wildlife campaigners, some of whom wept and shouted “murderers”, rangers in an inflatable boat injected anaesthetic into the 4.5m (14ft) whale, which took about ten minutes to take effect.

The whale was seen thrashing about as it was guided close to shore. Officials reached out to stroke the calf before others carefully hoisted it on to a tarpaulin. Colin was then pulled into a tent on the beach.

A wildlife group organised a legal injunction to prevent the whale being destroyed, but was unable to serve the documents in time to save its life.

The parks service was investigating reports of an adult whale being eaten by sharks off the southern state of Victoria. Officials hoped to determine whether it was the missing mother.

To read, 'Leviathan,' by Philip Hoare - An extraordinary journey into the underwater world of the whale -- to tie in with a BBC film-length documentary hosted also by the author, click here.

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