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HONG KONG: The number of Indo-Pacific humpback dolphins seen around Hong Kong has increased as the pause in high-speed ferry traffic due to the coronavirus allows endangered species to return, scientists said.
Marine scientist Lindsay Porter from the University of St Andrews said the mammals, also known as Chinese white dolphins and pink dolphins, were returning to parts of the Pearl River Delta that they normally avoided due to ferries connecting Hong Kong and Macau.
The number of dolphins in the area had increased by as much as 30 percent since March, when ferry traffic was suspended, giving scientists a unique opportunity to study how underwater noise affected their behavior, he said.
“These waters, which were once one of Hong Kong’s busiest waterways, have now become very calm,” said Porter, who has studied dolphins for three decades since Hong Kong.
From a small rubber boat, Porter and his team throw microphones into the water and use drones to monitor dolphins.
The research suggested that the dolphins had adapted more quickly than expected to the calm environment, and the population is likely to recover when those stressors are removed, Porter said.
Scientists believe there are about 2,000 dolphins in the entire Pearl River Estuary. A 2019 Hong Kong government survey found that only about 52 dolphins entered the waters around the Asian financial center, but Porter believes the actual number may be slightly higher.
“Sometimes I feel like we are looking at the slow disappearance of this population, which can be really sad,” he said.
Still, even if this population’s decline couldn’t be stopped, the research could help other dolphin populations elsewhere, he said.
Hong Kong’s conservation plans have focused on opening marine parks, where boat traffic is limited but not prohibited. Three of those areas are frequented by dolphins.
Hong Kong’s WWF, a conservation group, and Porter said such measures were inadequate as dolphins were still in danger of being hit by ferries as they moved between protected areas.
“It means that if we had a comprehensive management plan in Hong Kong with more effective conservation measures, we could quickly halt the decline in the dolphin population,” he said.
