In Hong Kong, dolphins are drowning in noise pollution

Similar research in New Zealand showed that ambient noise levels in shipping channels almost tripled in just 12 hours during the March 2020 lockdown. The contact range of fish and dolphins has increased by 65%.

“What was most surprising was the scale and speed at which this happened,” says Matt Pine, lead author of the study. “The benefits are immediate. »

According to experts, no attention has been paid to noise pollution. A review of the literature published in the journal in 2021 Science Of the 500 studies analyzed, 90% concluded that excessive noise causes “significant harm” to marine mammals such as whales, seals and dolphins, and four-fifths of fish and invertebrates.

“We urgently need to take action against noise,” said Carlos Duarte, a professor of marine sciences at Saudi Arabia’s King Abdullah University of Science and Technology, who also conducted the study. “All the attention is on climate change, overfishing, plastic and habitat loss. But in reality, the threat to the ocean’s soundscape has not received the attention it deserves. »

Duarte and his team found that the ocean’s soundscapes are changing due to the decline of “sound-making” animals and the rise of anthropogenic pollution. In the last 50 years, shipping has increased low-frequency noise on major routes 32 times.

Benjamin Colbert, a researcher at the University of Maryland’s Center for Environmental Sciences, says the effects of noise pollution can ripple across the animal kingdom, beyond charismatic species like white dolphins.

“Some species, dolphins, toothed whales and killer whales, use echolocation, sound, to hunt for prey, and it’s clear that calmer oceans are important to them,” says Colbert. “But there are still many animals that have not been studied. For example, this applies to about 30,000 species of fish on the planet.

Sound travels faster than light in the ocean. Used by all organisms, krill (Euphausiacea) to rays (Batoidea). humpback whales (Megaptera novaeangliae) sing complex mating songs with regional dialects; some shrimp produce a snap to startle their prey; andOpsanus tauThe species currently being studied by M. Colbert poses an interesting mating call.


On a recent trip with Ms. Woo on a small research vessel, I see her looking out over the 54-kilometer Hong Kong-Zhuhai-Macau Bridge, the world’s longest sea crossing. The $20 billion structure, which required the creation of two islands and an underwater tunnel, opened in 2018 to connect three Asian cities as part of the Guangdong-Hong Greater Bay Area.Kong-Macao. This construction, spread over ten years, caused a lot of noise pollution. The passage then sends an echo out to sea.

“This construction caused a lot of damage and disruption,” says Doris Woo. “But we still don’t fully understand the extent of it. And things only get worse. »

Of course, they will only get worse if there is no change. WWF has proposed several noise management practices: banning construction in dolphin habitats, restoring nature-based shorelines, combating illegal fishing, imposing speed limits on ferries, and reducing the frequency of trips. . A survey conducted by the Hong Kong Public Opinion Research Institute found that people are willing to pay higher rates and extend these rates for trips to protect dolphins.

Other solutions are available. Electrification of the fleet and deployment of more efficient propellers have already begun. More dramatically, air bubbles are used to act as a noise screen when the seabed is pounded, and speakers that play reef sounds attract fish to damaged coral reefs. For the first time in the world, the Regulatory Framework of the European Union has set itself the goal of reducing man-made noise in the oceans.

It is easier to do these actions than in Hong Kong. Ongoing development projects there include a 93-kilometer undersea gas pipeline and a reclamation project called Lantau Tomorrow to create 1,700 hectares off the coast of Hong Kong.

“We’re fighting the current,” cries Ms. Wu as she raises an acoustic monitor over the choppy waters of the South China Sea. “But there is still time. »

Mr. Duarte shakes his head. “Covid-19 has created a compelling, unplanned experiment for marine life recovery,” he said. “Once the noise sources are removed, the benefits are almost immediate. It will be cheaper to fix this problem now before more damage is done. »

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