Marine consultants hired by the Airport Authority should present facts to back up their claims that building a third runway at Chek Lap Kok would not threaten Chinese white dolphins in the area, a local conservationist says.
Dr Samuel Hung Ka-yiu, Dolphin Conservation Society chairman, issued the challenge after two overseas consultants said last month that dolphins displaced by the project might return.
The consultants were just "guessing blindly without any supporting facts", Hung said.
He also accused one of them, Thomas Jefferson, of misleading the public when he claimed dolphin numbers fell to 50 during reclamation for the Chek Lap Kok airport and rebounded to 100 after the airport opened in 1998.
"When Jefferson began to survey the dolphins in 1995, the reclamation had been completed already," Hung said. "No one knew how many dolphins were there before the project."
The other consultant, Bernd Wursig, declared with confidence on June 27 that the dolphins would return when disruption from the works ended.
The dispute over the prospects for the dolphin began after the government released its environmental impact assessment report for a public consultation that is to run until July 19.
Hung said the report failed to address the immediate loss of habitat at the start of reclamation work and the effect of continuous disturbance over the seven years that the project would take.
Hung said his own studies showed land reclamation in Tuen Mun and in Penny's Bay, where the Disneyland theme park is located, had expelled the mammals, and sightings in the two areas were now rare.
The authority responded that it was "inappropriate and unreasonable" for Hung to cite the two reclamation projects, which, unlike its own plan, did not establish marine parks to mitigate the effects of the works.
"We do not agree that local reclamation projects will drive the dolphins away," a spokesman said.
Hung also said that the report failed to explain how the proposed 2,400-hectare marine park could replace the long-established habitats that would be lost if the project went ahead.
He cited academic papers from 2004 and 2009 that he co-authored with Jefferson and Wursig which stated it was "virtually impossible" to mitigate the impact of land reclamation on dolphins.
Watch: In the summer of 2013, SCMP took a look at Hong Kong's pink dolphin habitat