Chinese dolphin population recovered remarkably after ferry route halt – Researcher

Marine biologist, Lindsay Porter, told Macau News Agency that the Pearl River Delta population Chinese white dolphin population had an almost “instantaneous” recovery shortly after ferry routes between Macau and Hong Kong were halted due to the Covid-19 pandemic.

According to Ms. Porter, who has been studying local dolphin populations for over 25 years, data provided by Chinese researchers showed that there are currently about 2,000 Chinese white dolphins in waters under the country’s jurisdiction, with some 200 individuals in Hong Kong waters.

“For the last 20 odd years, there has been a decline in the number of dolphins that we’ve seen in Hong Kong waters, where most of my studies are based. The most alarming is that the number of calves that are born and the number of baby dolphins that survive is very low,” Porter told MNA.

The Institute of Science and Environment of USJ will hold an online public lecture titled ‘Seas Alive! Understanding the whales, dolphins and porpoises of Macau and adjacent waters” with Porter as the main speaker today at 5:00pm.

She is also currently an Honorary Research Fellow of the Sea Mammal Research Unit (SMRU) of the University of St. Andrews (Scotland), the world’s largest research and teaching facility dedicated to the study of marine mammals.

According to the biologist, one of the main issues impacting marine mammal species in Hong Kong is the frequent fast ferry shipping lanes that go to Macau and other Mainland Chinese ports in the Pearl River Delta.

“Sometimes there could be a ferry to Macau every seven minutes; it’s a constant flow of traffic. When the ferry stopped in late February, it was amazing how quickly dolphins and porpoises, the other resident marine mammal, started using those ferry lanes they never used to use at all,” the biologist told MNA.

“We managed to get World Wide Fund for Nature funding to start work immediately and since then we’ve been conducting boat surveys, and we’ve got underwater listening stations all over the southern part of Hong Kong where ferries used to go and we’ve seen more and more individual dolphins”.

All ferry services between Macau and Hong Kong – operated by Turbojet and Cotai Water Jet – have been suspended due to the pandemic since February 4.

According to the marine researcher, the halt in ferry traffic allowed dolphins to use these ferry route areas instead of the one or two pockets of coastal habitat in between shipping lanes that they can usually use.

“It’s remarkable. I’ve noticed there are no more fast ferries, which we normally when doing research have to avoid as they come passing by at 45 knots an hour […] There’s no underwater engine or boat noise. Then suddenly there’s dolphins and porpoises all around us in areas we would rarely see them before,” Porter noted.

The research conducted has shown that the reduction in underwater noise levels correlated with a high number of calves born, however, Porter noted that five dolphins were found dead in the last few weeks, showing that stopping ferries alone is not enough to safeguard the species.

Porter is one of the backers of the Emergency Action Plan for the Pearl River Delta Population of the Chinese White Dolphin, presented by WWF-Hong Kong and other partners in June, pleading with Hong Kong authorities to designate a Dolphin Conservation Management Area to protect important feeding and socializing habitats in western and southern Lantau waters by 2024.

Southern and western Lantau provides a long and continuous natural coastline with abundant prey, making it a critical dolphin conservation management area, and the area has been described by conservationist groups as particularly important for dolphins since 2015 when they started moving away from large-scale developments in northern Lantau, including Hong Kong International Airport expansion and the Hong Kong-Zhuhai-Macau Bridge construction.

Proposed sanctuary safe areas

“This time WWF has taken this as their core mission as a united effort with other groups […] A lot of the work I do was used for their emergency plan […] We want to gather momentum to try and save some of the dolphins’ habitat because we’ve seen them disappear right in front of us and it’s so frustrating because we just need to have a coordinated plan to help alleviate the pressure and this will give them a much better chance of survival,” the researcher told MNA.

Porter also noted that she hopes more cooperation can be had with Macau authorities to study the dolphin population in local waters, as sightings have increased.

“Our research is mainly divided into three jurisdictions, Macau, Mainland and Hong Kong and it has always been quite challenging for Hong Kong based researchers to work in Mainland China in the Pearl River Delta estuary, but we have managed to make some collaborative work with land institutes,” she noted.

Porter advised that the most significant work done was in that area between Macau and Hong Kong, where through underwater acoustic recorders, marine biologists and conservationists were able to monitor, not just dolphin numbers, but also the abundance of fish species on which they prey, such as croaker fish.

“[For 25 years] I’ve been following individual dolphins in the Hong Kong Pearl River Delta estuary. You can identify individual dolphins by their colouration, the shape of their fin. With a frequent enough boat service, you can follow these individuals over the years. There are dolphins I’ve seen growing up for 20 years and grew up,” she noted