WWF-Hong Kong on Thursday urged the government to put in place marine traffic mitigation measures in South Lantau waters, after its study found that Chinese white dolphins have been more active in the area due to reduced sea traffic during the pandemic.

The study found that 60 percent more dolphins have been out foraging since high-speed ferry services were suspended in the area from 2020.

Doris Woo, a cetacean conservation project manager with the green group, said the rebound has to do with a decrease in sea traffic.

"For this kind of increase [in dolphin numbers] we believe it's because we have taken out the threat of marine traffic. For dolphins, they benefit immediately from having a larger and less disturbed habitat to use, so that's why they exhibit more of these kinds of behaviours," she said.

She urged the government to implement dolphin-friendly measures before resuming cross-border ferry operation, such as restricting ferry speeds and setting up buffer zones.

"We strongly encourage the government to set up core and buffer areas covering key dolphin habitats, with providing a less disturbed and ecological channel for the buffer areas for dolphins to swim between these core areas," she said.

The group said the Chinese white dolphins population has dropped by over 80 percent in the past 17 years, with just around 37 left in Hong Kong waters at the moment.