Last summer, workers began an eight-year project to build a third runway in waters beside Hong Kong International Airport. Officials say that the estimated $18 billion project will allow Hong Kong to maintain its status as a global aviation hub and that a marine park should be created nearby after the runway is completed, around 2023, to compensate for the planned destruction of an area of dolphin habitat roughly twice the size of Central Park in New York City.
But biologists say the third runway will compound the environmental damage of high-speed ferry traffic and other infrastructure projects, including a nearly completed bridge and tunnel crossing that will link Hong Kong and Macau to the Chinese mainland. They say Hong Kong — a commercial center with a British-style legal system and a high degree of political autonomy — appears increasingly bent on destroying its native dolphins through economic development, just as China drove the Yangtze River dolphin to extinction a decade ago.
“It’s such a terrible image for Hong Kong that we cannot protect our dolphins because we want even more money,” said Samuel Hung, a biologist who has been studying the estuary’s dolphins for decades and has battled the third runway project — unsuccessfully — in court.
The population of Chinese white dolphins in the coastal waters of the Pearl River estuary is estimated to be about 2,500, making it the largest near China’s coast and perhaps also in Southeast Asia. A report published in March by the scientific journal PLOS One, based on a four-and-a-half-year survey by University of Hong Kong biologists, estimated that “at least 368 dolphins used Hong Kong’s territorial waters as part of their range.”
Mr. Hung’s government-financed surveys, which use a different methodology, indicate that the dolphin abundance in Hong Kong waters — an estimate of how many dolphins are present at any one time — dropped to a record low of 65 in 2015, from 188 in 2003. “We’re at a critical juncture,” he said.
The Airport Authority has said that the third runway will significantly expand flight capacity at the airport, which served 70.5 million passengers last year, and provide $58 billion in additional revenue by 2061. Supporters of the plan include Cathay Pacific Airways, Hong Kong’s flagship carrier.
“If there was already a third runway, it would be utilized,” said Will Horton, a senior analyst in Hong Kong with the Capa Center for Aviation, based in Australia. “Local airlines are not growing as fast as they could, while foreign airlines are waiting to add flights.”
But critics call the third runway project a white elephant, in part because it is unclear how much airspace mainland aviation authorities will allocate to Hong Kong in the coming decades, or whether the city airport can even hope to compete over the long term with its mainland Chinese counterparts.
Albert Cheng, an aircraft engineer and former Hong Kong legislator, said the city should not bother investing in a third runway because it had already been “marginalized by China in every aspect” and would eventually lose its cachet as Asia’s aviation hub, lowering demand for flights.
Another issue is whether the project’s proponents have accurately conveyed its environmental risks and whether the government should have allowed it to go forward.
Some critics say that the project should not have been approved because of the potential impact on dolphins and that HSBC, the project’s financial adviser, bears some responsibility because it has adopted the Equator Principles, a set of standards many institutions apply to ensure the projects they finance or advise do not harm people or the environment.
HSBC has been advising the Airport Authority “on the preparation of the environmental information that financing banks will need, when selected, in order to evaluate this project as lenders in accordance with the Equator Principles,” Adam Harper, a spokesman for the bank, said in response to emailed questions about the runway project and the bank’s corporate due diligence process. “We are committed to the Equator Principles.”
The Airport Authority has said that its marine park proposal is based on international best practices and that noise from construction vessels will not cause long-term harm to dolphins because they are “expected to simply keep out of the way, which is an expected reaction by intelligent animals.”
The authority said in a statement that the proposed marine park was nearly four times the size of the runway project and would “pave the way” for a rebound of the dolphin population in Lantau’s northern waters. It would have been impractical to establish a park there during the construction phase, the statement said, mainly because the designation would have precluded building.
But biologists say the proposed park would not protect the dolphins from construction-related noise between now and 2023, or cover critical dolphin habitats in Lantau’s southwestern waters.
“The saddest thing is that the experts from the airport say, ‘It’s O.K. for them to leave. They’ll come back later,’” said Mak Hei Man, one of several researchers who conduct dolphin surveys off Lantau as part of a government-financed research project that began in the 1990s.
“But in mainland waters, it’s even worse,” she said, referring to pollution and disturbances.
Billy Hau, a University of Hong Kong biologist and a member of the city’s Advisory Council on the Environment, said that the runway project illustrated the problems with the environmental permit system.
Hong Kong’s Environmental Protection Department has rejected just seven of 249 applications for approval of environmental impact assessments since the permit review process became legally binding in 1998. Mr. Hau said the process lacked accountability, because it did not allow for public hearings or the formation of expert panels to review especially contentious projects.
“Many people criticize this as unfair because most of the proponents either have a very strong interest in government, or they’re actually government departments themselves,” he said.
The department disputed this, saying by email that the process allowed both the public and the Advisory Council on the Environment to inspect projects twice.
John Wang, a biologist at Trent University in Canada who studies Hong Kong’s dolphins, said that the process had effectively allowed the Airport Authority to gamble with the dolphins’ lives. Even after the release of an environmental impact study, he said, it remains unclear precisely how dolphins may respond to runway construction noise or to future changes in high-speed ferry or shipping routes.
Mr. Wang said that at some point, the dolphins could become so stressed and confused by the noise in the estuary that they would stop swimming away from noise sources, leading some observers to assume they were unbothered.
“People will misunderstand that, saying, ‘Oh, they’ve acclimatized, they’re O.K. now,’” he said, standing on the deck of the survey boat. “No. They’ve just given up.”