Established in 2003, the Hong Kong Dolphin Conservation Society (HKDCS) is the only organisation dedicated solely to the protection of local dolphin, porpoise and whale populations in Hong Kong waters.

In particular, the organisation is recognised for its work on the elusive Chinese white dolphin population in southern Hong Kong, a local species which is loved by many but rarely seen due to its dwindling population.

HKDCS aims to raise awareness on the biology and implemented conservation of local dolphins and porpoises in Hong Kong through preservation of species and their habitats. With this comes an increased public awareness on the threats posed to cetaceans such as marine pollution, fishery by-catch and attitudes towards animals concerning captivity, whaling and poaching. The organisation also aims to question the standards of dolphin-watching activities and supports ethical and sustainable tourism.

With this, the organisation strives to educate the public on the importance of dolphin conservation and offers opportunities for research interns and volunteers to participate in efforts. They also offer boat tours for dolphin-watching in order to educate the public on appropriate practices (see how to get involved below).

HKDCS conducts scientific research on local populations through a variety of survey techniques carried out by land, air or sea (see methodology below). The body of research accumulated by the organisation feeds into the conservation of species and provides a forum for discussing the plight of local populations.

Chinese white dolphins (Sousa chinensis)

Biology and Life History

The Chinese white dolphin (Sousa chinensis; also affectionately known as the Hong Kong pink dolphin) is a subspecies of the Indo-Pacific Humpback dolphin found in coastal areas of South-East Asia and Australia. In the context of the former, there are four major populations found in the Pearl River (or Zhujiang) Estuary, Xiamen, Beibu Bay and Leizhou.

At birth calfs are grey with mottled pink spots and can be up to 1m in length. Conversely adults are white or pink in colour, the latter due to thermoregulation properties of blood vessels close to the surface of the skin. Adults can live up to 40 years of age, weighing between 150-230kg and reaching lengths of 2 to 3m. Chinese white dolphins are considered social creatures and can be sometimes be found in groups or ‘pods’.

Chinese white dolphin mother (white/pink) and calf (mottled grey)

Juvenile calf displays a mottled grey pink colour and swims alongside its mother who appears pink in colour.


Conservation and protection status 

According to the International Union for Conservation of Nature (IUCN) red list (the world’s most comprehensive inventory of the global conservation status of biological species) the Indo-Pacific Humpback Dolphin status is listed as ‘Near Threatened’. This finding is derived from studies on the status of the overall population, not exclusive to the South China Sea.

As a result the species is listed in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) Appendix I which describes species threatened with extinction. Thus the trade of these species is permitted only in exceptional circumstances. The Chinese white dolphin is also listed in the Convention on Migratory Species’ (CMS) Appendix II concerning migratory species that have an unfavourable conservation status or would benefit significantly from international co-operation.

In China, the species is listed as a “Grade 1 National Key Protected Species” and in Hong Kong they are protected under Wild Animals Protection Ordinance (Cap 170) and Protection of Endangered Species of Animals and Plant Ordinance (Cap 586).

Due to the fragility of the population, Sha Chau and Lung Kwu Chau Marine Parks were designated in 1996, aiming to protect some of the most important habitats in Hong Kong. And in December 2016, the Brothers Marine Park was established to compensate for the building of new infrastructures on or near Lantau island (see threats below).

Chinese white dolphin population monitoring

The largest population of the South-East Asian subspecies is found in coastal areas of the Pearl River Estuary which includes Hong Kong waters. They are found in the southwest region of Hong Kong around Lantau Island in the north, west and south.

According to the HKDCS’ Director Samuel Hung Ka-Yiu  the population of Sousa chinensis in Hong Kong waters has fallen from 158 in 2003 to only 61 dolphins in 2014. Extrapolating from this trend it would appear that the local population is extremely vulnerable.

The HKDCS employs a variety of techniques to estimate population size and gather important information of dolphin biology and status:

Vessel surveys

While onboard, researchers use standard line-transect methodology to record details of cetacean sightings. Researchers ‘on effort’ take turns recording data and searching for dolphins using the naked eye and binoculars. Throughout the course of the survey, the time, position, boat speed, weather condition (Beaufort scale and visibility) and the distance travelled are recorded. When dolphins are spotted, sighting time, distance and angle, position, group size, approximate age, environmental conditions and behaviours are noted. The boat will then slowly approach the dolphins in order for photo-identification to occur. During this time biopsy sampling may also be possible.

Photo-identification

When dolphins are encountered photos are taken for identification purposes. This is because unique features on the back and dorsal fin such as nicks, scars, colouring and shape help identify individuals and thus their home range and general behaviours.

Helicopter surveys

This surveying technique is used when areas are inaccessible by boat, when time is limited and the area needed to be covered is large. However, due to the costs of helicopter surveys they are not idea for routine line transect surveys.

Land-based surveys

Surveys are conducted at elevation points in areas where dolphin density is high. These surveys cover more in the way of the behaviour and times of surfacing and diving, as well as responses to vessels. This is a cheap and non-invasive method of studying populations.

Stranding identification

Dolphin carcasses may be found along the coastline of Hong Kong’s waters. Samples from such individuals can provide important information about threats to populations through determining the cause of death. For instance blubber, liver and kidney samples can be used to assess ecotoxology. Carcasses also provide information on the identity of the specimen as well as behaviour, age and gender.

Acoustic monitoring

Along with regular line-transect surveys, dolphin acoustics can be monitored in order to investigate how vocalisations change in response to anthropogenic influences, thereby revealing information about behaviour.

What are the threats to the Chinese white dolphin?

Threats to the Chinese white dolphin have ultimately resulted in their population decline. Through identifying these threats, organisations such as the HKDCS can better tailor conservation policies and inform others on the plight of the Chinese white dolphin.

So what are the major threats the Hong Kong dolphin population faces?

Habitat loss and coastal development

New infrastructure has the potential to reduce and/or disturb breeding, nursery and foraging grounds the Chinese white dolphin, forcing them to move to less suitable habitats. And in the context of Hong Kong where developable land is sparse, land reclamation is regularly implemented contributing to a decline and disturbance in dolphin habitat. Infrastructures may also block or affect movement between important habitats.

Coastal development also brings other issues besides habitat loss namely water pollution (affecting dolphins directly and their food stocks), noise pollution and increased water traffic, ultimately increasing the risk of mortality.

Recent developments such as the Macau-Zhuhai bridge linking the Chinese mainland to Hong Kong and construction of the Third Runway at Chep Lap Kok International Airport are examples of developments that have threatened dolphin populations. And despite the recent opening of the Brothers Marine Park located near these projects, few dolphins have been sighted.

A pod in front of the Macao-Zhuhai bridge

Increased marine traffic: vessel collision and noise pollution

As mentioned, alongside development projects comes increased underwater construction works, increasing marine traffic and high levels of noise pollution. This can lead to changes in dolphin behaviour (e.g. acoustic signalling) and thus increased rates of injury and death. This is because dolphins rely on echolocation for hunting, communication and navigation in order to locate their peers, fish and other objects.

Vessel collision with dolphins also has the potential to occur. For instance, there are many high-speed ferries between Hong Kong, Macau and other cites in the Pearl River area which traverse key dolphin habitats around Lantau waters. Scars, nicks and marks can sometimes be observed on individuals, perhaps as a result of collision with vessel propellers.

Fishing practices: over-fishing, by-catch and net entanglement

Although trawling practices have been banned in Hong Kong, there is still potential for dolphin food stocks to be undermined by fishing practices. These practices also increase the risk that dolphins may be caught in nets as species by-catch or as a result of improper disposal of fishing nets. With regard to the former, dolphins may be drawn to large shoals of fish which have been caught by fishermen, thus resulting in unfortunate entanglement. These issues are only worsened by the poor visibility of the South China Sea and disturbance to dolphin communication as a result of noise pollution.

How can you get involved?

Aside from campaigning and petitions against developments and practices which are detrimental to cetacean wellbeing, Hong Kong Dolphin Conservation Society provides opportunities for the public and scientific hopefuls to get involved.

A 2 to 3 month research internship programme is available to those with a keen interest in cetacean and marine biology. As part of the programme, interns are required to document their experiences in a journal, detailing the research they have partaken in and their motivations behind participating. There are also volunteer opportunities available for those who may be constrained by time.

Similar to this, HKDCS runs a University Student Programme for local Hong Kong students who want to learn about cetacean biology. A select few of the participants may apply for the internship programme after.

The society also runs Dolphin Research Trips for those who are interested in learning more about Hong Kong’s elusive Chinese white dolphins. These trips are quite infrequent so be sure to check out the HKDCS Facebook page for further details.

Useful links

http://www.hkdcs.org

http://www.afcd.gov.hk/english/conservation/con_mar/con_mar_chi/con_mar_chi_chi/con_mar_chi_chi.html

http://www.wwf.org.hk/en/whatwedo/conservation/species/chiwhitedolphin/threats/

http://www.news.nationalgeographic.com/2016/05/pink-dolphins-hong-kong/

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