In the midst of environmental hearings on a proposed third runway, conservation authorities have made a surprise pledge to designate two new marine parks off Lantau Island by 2017.
The announcement was made as government advisers continued deliberation on the Airport Authority's environmental report on the proposed additional runway at Chek Lap Kok.
It said it was a response to public concern and part of its own Chinese white dolphin conservation programme.
The proposed parks will cover 660 hectares off southwest Lantau and 1,270 hectares around the Soko Islands archipelago, in a bid to enhance protection for the endangered dolphin and finless porpoise.
But Dolphin Conservation Society chairman Dr Samuel Hung Ka-yiu suspected the move was made by the government to take pressure off the authority.
"The authority's [report] and the long-delayed designation of the two marine parks cannot be grouped together.
"We never said this could be a compensation measure for the third runway and it cannot be one. Marine parks cannot mitigate the [650 hectares of] habitat loss," he said.
He urged subcommittee members of the Advisory Council on the Environment, who will meet today, not to accept the new plans as justification for the airport expansion.
An authority spokesman said the government's latest park plan was not part of its report but it would "complement" its own conservation measures to protect the dolphin population.
"We will launch another round of public engagement in 2015 and take other necessary steps and seek to complete the statutory procedure for the designation by early 2017," a department spokesman said.
Proposals to designate the two marine parks span back to 2002 but never came to fruition due to opposition from the fisheries sector and Lantau residents.
Dr Michael Lau Wai-neng, a senior programme head at WWF Hong Kong, said the move was welcome, but was not enough. "There is a consensus among scientists that [dolphin] habitat can only be protected by linking up the parks along the Tai O fringe, to the existing Sha Chau and Lung Kwu Chau Marine Park," he said.
The authority's proposal for a 2,400 hectare marine park connecting Sha Chau and another proposed park northeast of Lantau has been dismissed as ineffectual as it would be designated only after the runway's completion in 2023.
Lawmaker Steven Ho Chun-yin, of the agriculture and fisheries sector, said the industry would likely oppose the park plan if it hurt fishermen's livelihoods.
He said that on issue would be whether fishing permits for the marine parks would be allowed to be transferable.
"The government will have to consult the industry further," Ho said.
The Country and Marine Parks Board will be consulted on the draft maps at a "suitable time" before it is published for public inspection, the department said.