Chinese White Dolphin – Resource protection is not optimistic

Chinese White Dolphin – Resource protection is not optimistic

Recently, researcher Prof. Li Songhai from the Institute of Deep-Sea Science and Engineering of the Chinese Academy of Sciences published a Letter article titled “Humpback dolphins at risk of extinction” in the journal Science, proposing that Chinese white dolphins and other dolphins are at risk of extinction, and drawing attention to the existential threat of these animals. The article once again sounded the alarm for the protection of the Chinese white dolphin. So, what kind of species is the Chinese white dolphin? What are the endangered factors? What are the protective measures?
Chinese White Dolphin (Sousa chinensis)
Photo © Rajitha

Basic overview
The Chinese white dolphin (Sousa chinensis), also known as the Indo-Pacific Humpback Dolphin, belongs to the order Cetacea, suborder Odontocetes (Toothed cetacean) and family Delphinidae . In addition to the Chinese white dolphin, the genus White Dolphin also includes three species: Atlantic Humpback Dolphin (Sousa teuszii), Indian Ocean Humpback Dolphin (Sousa plumbea), and Australian Humpback Dolphin (Sousa sahulensis). The Chinese white dolphins are respected as “Mazu fish” by fishermen in Fujian and Guangdong. Due to their rarity, they are also known as “water giant pandas”. In 1997, they were selected as the mascot of Hong Kong’s return to the motherland.
Four species of hump back dolphins

Age and body-color
A significant characteristic of the Chinese white dolphin is that its body color will change with age, from the initial dark gray to the old gray. It is noteworthy that the adult Chinese white dolphin we usually see in the sea is pink, not its own color, but formed by congestion of blood vessels under the skin after strenuous exercise, which is related to regulating body temperature.
Mother (white) and calf (dark gray)

Echolocation system
The Chinese white dolphin has small eyes and poor vision. Their predation in the water, avoiding obstacles, and communicating with each other mainly rely on echolocation systems. There is an air sac under the nostril, which makes sound by the opening and closing of nasal congestion. This kind of sound line is concentrated in a special organ composed of fat on the forehead bulge, and it is emitted at a certain frequency; when the sound hits different objects, it reflects different frequency signals, Received by a groove made of fat in the dolphin’s lower palate, and transferred to the inner ear for positioning.
Schematic diagram of echolocation system

The reproductive ability of Chinese white dolphins is relatively weak. Their lifespan is generally 30-40 years, and they reach sexual maturity at 3 to 5 years old. The gestation period is 10-11 months. Each adult can only give birth to one cub, and this is why it is so scarce. Although we and the Chinese white dolphins are the same mammals, the baby dolphins are born in the opposite direction of ours. The baby dolphins are born with the tail first, and then the head is exposed so that the baby dolphin will not choke during the birth process. After the baby dolphins are born, they are led by the mother dolphins to learn to swim. The lactation period is about 11 to 20 months. The mother and the baby are inseparable throughout the breastfeeding process.

Population status
The Chinese white dolphins are not unique to China. They are mainly distributed from the Pacific Ocean to the Indian Ocean and the coasts of Southeast Asia, extending north to the southeast coast of China. It is estimated that the total number is about 6000. China is the most critical habitat of the Chinese white dolphins in the world. The quantity is approximately 4000-5000 heads. In China, Chinese white dolphins mainly inhabit the estuary waters south of the Yangtze River estuary, including Sandu’ao, Xiamen Bay, and Dong-shan Bay in Fujian, the western waters of Taiwan Island, and Hanjiang Estuary, Pearl River Estuary, Moyang River Estuary and the Leizhou Peninsula in Guangdong. In the eastern seas, the seas near Sanya, Hainan, and the Beibu Gulf of Guangxi, the Pearl River Estuary waters (including Hong Kong and Macao) have the largest number, exceeding 2,000.
Distribution of Chinese White Dolphins

Endangered factors
As the flagship animal in the coastal and coastal waters, the Chinese white dolphin has irreplaceable ecological and conservation biological value. As a nearshore fish, its activity area overlaps with the human activity area and is susceptible to human activities. In recent years, they have been threatened by many aspects such as accidental fishery catch, ship collision, habitat destruction, environmental pollution, food shortage, and underwater noise; hence they are facing the risk of extinction.

Protection situation
Species legislation: In 1988, it was listed as a national first-level protected wildlife. In 1991, it was listed in Appendix I by CITES of the Convention on International Trade in Endangered Species of Wild Fauna and Flora, and it was also protected by the CMS of the Convention on the Protection of Migratory Species. In 2008, it was listed in the “International Union for Conservation of Nature”. IUCN was upgraded from “Data Deficient” to “Near Threaten”, among which Taiwan’s west coast population was listed as “Critically Endangered”.

Formulate and implement relevant protection plans and plans: In 2017, the Ministry of Agriculture organized and compiled the “Chinese White Dolphin Conservation Action Plan (2017-2026)”. The main purpose is to better protect and restore the Chinese white dolphin population and effectively responding to the new problems and challenges faced by the protection of Chinese white dolphins, unified deployment of the management of Chinese white dolphins nationwide.

The Chinese white dolphin is a friend of mankind. To protect the Chinese white dolphin and the ecological environment is to protect ourselves. Get to know Chinese white dolphins, understand Chinese white dolphins, care for Chinese white dolphins, enhance public awareness of protection and participation, and call on the public to actively participate in protection work, start with me, start with small things, care for Chinese white dolphins, and maintain biodiversity. Contribute to building a beautiful world where man and nature develop harmoniously.

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Reference :

Li, S., 2020. Humpback dolphins at risk of extinction. Science367(6484), pp.1313-1314.

Rajitha Dissanayake

Researcher in the field of Marine Mammals and Bio-acoustic

I'm a Master’s student in marine mammals and bio-acoustic laboratory, Institute of Deep-Sea Science and Engineering (IDSSE), Chinese Academy of Sciences (CAS) and focusing on the sustainable environmental application, conservation, and exploring all aspects of the ecology and behavior of marine mammals.

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