“THE dolphin is clever, cute, kind, active and inoffensive. Exactly the character of Hong Kong.” So said a local member of a committee appointed by China to oversee the end of British rule over Hong Kong in 1997. The body had decided that the pink dolphin, a rare type sometimes seen cavorting in the territory’s harbour, would be a mascot of the handover festivities. Since then, however, the animal’s fate has not been an encouraging portent of the territory’s post-colonial progress. Hong Kong’s dolphins are in perilous decline.

They belong to a type of dolphin that lives off China’s shores called sousa chinensis, or the Chinese White (though they are grey when born and pinkish as adults). They prefer the brackish water of estuaries, where they are threatened by fishing and water-polluting factories. In Hong Kong there is a different danger: the relentless building of megastructures, including one of the world’s longest bridges. Before the British left they built an airport on 938 hectares (2,300 acres) of reclaimed land: a new runway is planned that will require 650 more.

Such work appears to be driving the dolphins farther away. In a survey conducted in 2003, scientists spotted 188 dolphins around Lantau island, the animal’s main habitat in Hong Kong and the site of the airport. In 2015 they saw just 65. Experts are not convinced that the animals are safer when they move elsewhere along China’s coast. In 2010 there were thought to be 2,500 dolphins in the Pearl river delta (which includes Hong Kong)—the largest known group. But their numbers there are falling by around 2.5% annually, say scientists at the University of Hong Kong.

The government of Hong Kong appears half-hearted about protecting them. An official website promoting Lantau’s attractions uses pictures of the wrong species. Janet Walker of Hong Kong Dolphinwatch, which runs dolphin-spotting tours, complains that other boats sometimes ignore a code of conduct requiring them to keep away from the animals. The government, she says, are not keen on stricter enforcement.

Officials have pledged to open more “marine parks” where dolphin-threatening activities will be banned. But one that is planned around the airport will not open until 2023, when the new runway is due to open. Samuel Hung, who runs a government-funded study of the dolphins, says there is “no way” the animals will tolerate the disruption caused by the runway’s construction.

On July 1st Hong Kong will mark 20 years of Chinese rule. On the harbour-front, a sign promoting a celebratory event features a bright pink, winking dolphin and a blue-coloured friend. If the government wants to make use of delphinoid imagery in another 20 years, it will be embarrassing if none is left.