In busy Hong Kong waters live the Chinese white dolphin, also known as the ‘pink dolphin’, or the Indo-Pacific Humpback Dolphin, but this iconic species is rapidly disappearing.
The Pink Dolphins of Hong Kong
Guest Post by Karoline Hood
Though the Indo-Pacific Humpback Dolphins are considered to be part of a single widespread and highly variable species, some biologists consider Humpback Dolphins in the Indo-Pacific to consist of two species: S. plumbea in the western Indian Ocean, from South Africa to at least the east coast of India, and S. chinensis, from the east coast of India to China and Australia.
Dr Samuel Hung Ka-yiu is the Chairman of Hong Kong Dolphin Conservation Society and has been monitoring dolphins in Hong Kong waters since 1997. Dr. Hung’s 2015 report revealed that there were close to 158 dolphins in Hong Kong waters in 2003, but their population has plummeted to just 47 in recent years.
However, a 2017 study by researchers at the University of Hong Kong (HKU) delivered the first-ever comprehensive population assessment of the Chinese white dolphins that inhabit Hong Kong waters, and what they found differs from the common public belief.
In fact, “it differs very substantially from the estimates reported in Hong Kong for the past many years,” said Dr. Leszek Karczmarski, Associate Professor at the Swire Institute of Marine Science and School of Biological Sciences, HKU, who has instigated and supervised this study.
“Contrary to statements frequently repeated by various Hong Kong media, there is no such thing as ‘Hong Kong dolphin population,’” he added.
“The dolphins seen in Hong Kong waters represent an integral part of the Pearl River Estuary (PRE) population; they are not aware of the administrative border between Hong Kong and Mainland waters, frequently traverse these waters, and there are at least 368 dolphins that rely on Hong Kong waters as part of their home range,” said Mr. Stephen Chan, a Ph.D. student in Dr. Karczmarski’s Lab and the lead author of the study.
The Chinese white dolphins are also known to be in North Lantau waters near Castle Peak, Lung Kwu Chau, Sha Chau Marine Park, Chek Lap Kok and Tai O. They are also found in the waters south of Lantau, including Fan Lau and the Soko Islands.
History of the Pink Dolphin
The Chinese white dolphin was first observed in Hong Kong’s Pearl River Estuary over 300 years ago. However, it was not until the late 1980s that scientists began tracking their population and behaviour.
The ‘pink dolphin’ as it is colloquially known, became Hong Kong’s official mascot for the handover ceremony in 1997 when Britain returned the territory to China. Born grey, the dolphin gradually turns pink as it ages, and their pink hue is thought to be a result of flushing blood to the outer layers of the skin for regulation of body temperature.
Threats to the Pink Dolphin
The population of the Chinese white dolphins in the Pearl River Estuary inhabits one of the world’s most congested areas. Heavy marine traffic, increased development and severe water pollution has placed dolphins in these areas under enormous pressure. Such disruption to their habitat represents the greatest threat to the Chinese white dolphin.
Hong Kong waters are one of the world’s busiest waterways, with High-speed ferries coming to and from Macau with passenger and freight, which cut right through the dolphins’ habitat and can kill them in collisions. In addition to that underwater noise pollution from the boat’s engine which magnifies under the water affect their echolocation efficiency. Dolphins rely on sonar to navigate, communicate and find food.
Hong Kong’s rapid development projects pose a significant threat to dolphins in Hong Kong waters, with populations being impacted by the construction of the Hong Kong-Zhuhai-Macau bridge, which started in 2011, as well as the Hong Kong International Airport runway.
Yuki Lui Hiu-ying of the Hong Kong Dolphin Conservation Society (HKDCS) said that the increased shipping traffic and large scale developments in the region have negatively impacted dolphins in Hong Kong waters.
“We did a study and put Ecological Acoustic Recorders in the water and could hear a lot of dolphins, so we know they use that area to feed at night, and it’s an important habitat for them,” said Lui Hiu-ying.
“We urged the citizens to write to the government and to tell them we don’t want this huge construction that impacts the dolphins, we gathered a lot of comments from the citizens, but sadly, the government did not listen and passed the Environmental Impact Assessment Report, and the work started,” she said.
“We don’t have much hope, but we will still need to do something. We are bringing more awareness; I see more students and more Hong Kong people becoming aware, so I see a little hope.”
Added to this, increased pollution resulting from these construction projects is causing high calf mortality; with toxins killing young dolphins whose immune system is not strong enough to handle the increasingly inhospitable environment of the Pearl River Estuary.
How You Can Help
♣ Reduce rubbish such as straws, plastic knives and forks, plastic bags.
♣ Avoid using skin products that contain microbeads as eventually, they end up in the ocean.
♣ Write to local ferry companies and ask them to reroute or slow down.
♣ Sign the petition to reroute ferry traffic.
♣ Download our mobile game app, World of the Wild! Click here to download.
♣ Register your interest in My Green World’s Kids Corner education program.
♣ Sign up for My Green World’s newsletter here.
♣ Follow us on Facebook here.