One of the 10 groups said that contrary to what park managers suggested, there was little evidence that public displays of live animals promoted people's knowledge of conservation. 'To decide the issue, it is necessary to weigh up the educational value of displaying the crowd-drawing belugas with the unnecessary suffering caused by their capture, transportation and long-term confinement,' the Society for the Prevention of Cruelty to Animals said.

It said a study in 2007 by the Association of Zoos and Aquariums, of which Ocean Park is a member, did not show that visiting animal displays was educational for people or caused changes in their attitude. There were no statistically significant changes to people's knowledge after the visits.

However, Ocean Park quoted its own study, carried out in 2008, that found more than 80 per cent of visitors could recall the conservation message they learned. The park said animal exhibits from the polar regions could help raise public awareness on global climate change. 'Visitors can develop a greater respect for the animals and their habitats,' the park said yesterday.

In a letter to the South China Morning Post, the SPCA said the real issue was the welfare of the confined animals.

It said taking animals from the wild made them suffer. The life-spans of animals in captivity were usually lower than those in the wild.

'Complications during the capture process have been known to kill individual animals, while others die in holding pens or during transportation,' the group said. Educating the public did not have to rely on the 'capture, imprisonment and display of intelligent sentient beings', it said.

Ocean Park said it believed the collection and transport of wild belugas would be safe, based on two years of observation by Park staff of a collecting team with 20 years of experience in Russia, where the white whales would be caught. It said no belugas had died in transit in the past four years.

While no decision has been made, the park said it was well prepared to transport belugas, as its zoological team members had been sent to other animal facilities around the world to take part in transport and study techniques.

'We are also working closely with beluga experts from around the world, and would have them present at the park during and after the belugas' arrival to ensure the well-being of the animals,' the park said.

Recent research suggests that dolphins held in captivity had a longer lifespan than those living in the wild.

The Post reported on Thursday that Ocean Park is commissioning a public survey to determine whether it should capture a group of belugas from the wild in Russia to join its animal collection in its newly redeveloped aquarium facilities. The plan has drawn strong opposition from animal conservationists.

As well as the SPCA, the coalition includes the Animals Asia Foundation, the Humane Society International and the World Society for the Protection of Animals. The chairman of the Hong Kong Dolphin Conservation Society, Dr Samuel Hung Ka-yiu, said he was delighted to see animal welfare groups united against the plan.

Hung said it seemed the park's operators were in an internal struggle and had serious doubts over the plan. One of the major concerns was what alternatives to the belugas were available if the plan was dropped. He said aquariums worldwide had very strong demand for belugas and the mainland alone had bought dozens last year.

'Why do we have to compete with mainland aquariums? The mainland tourists are coming anyway and they won't come here for the belugas.'

Some people have launched a web petition, asking people to e-mail the park to voice their opposition and make pledges not to visit unless the plan is dropped.