Source: Hainan Daily
Chinese white dolphin skin color changes with age. Image courtesy of the Institute of Deep Sea, Chinese Academy of Sciences
Chinese white dolphin. (Infographic)
Chinese white dolphins of different ages swim in the southwest coastal waters of Hainan Island. Image courtesy of the Institute of Deep Sea, Chinese Academy of Sciences
I believe that many people have heard the warm story of dolphins rescuing people from the water since childhood, and such a gentle and lively marine mammal is widely loved by people. The popularity of the documentaries "Dolphin Bay" and "Dolphin" has made such special creatures love and enter the vision of more people.
Among the dolphins, there is a class of "marine giant pandas" due to the scarcity of the name, they are the Chinese white dolphin, also known as the Indo-Pacific camel dolphin, for the dolphin family camel dolphin is a small toothed cetacean, is the only national first-class protected animal in the dolphin family, is also the only cetacean named after the prefix of "China", and is also the mascot of Hong Kong's return to the motherland. In 2008, the Chinese white dolphin was assessed as "vulnerable" by the International Union for Conservation of Nature's (IUCN) Red List of Threatened Species.
As the flagship species in coastal and shallow waters, the Chinese white dolphin has been found in the southwest waters of Hainan Island in recent years, which has refreshed the academic understanding of the geographical distribution of this species and is of great significance to the ecological and environmental protection of Hainan coastal waters. How to scientifically do a good job in the research and protection of Chinese white dolphins, so that Qiongdao island can become the home of this group of marine spirits for a long time? This requires a multi-party collaboration.
Hainan also has Chinese white dolphins?
The discovery of researchers in the southwest waters of Hainan Island has pushed the geographical distribution range of Chinese white dolphins in China nearly 300 kilometers to the south
Swarms of dolphins appear in the offshore waters, sometimes jumping and sometimes diving, a scene that many fishermen in the southwestern waters of Hainan Island have seen.
The images that fishermen are accustomed to became significant in October 2013 by the intervention of a group of researchers at the Institute of Deep-Sea Sciences and Engineering of the Chinese Academy of Sciences.
At that time, the questionnaire survey of marine mammals and Hainan fishermen led by Li Songhai, a researcher at the institute, and participated in by associate researcher Lin Mingli and others, was being carried out. "During a month's investigation, we identified the fishermen with photos of Chinese white dolphins, and more than 50 people recognized that this dolphin had appeared in the southwest waters of Hainan Island." Lin Mingli said.
What excited the researchers the most was that a young fisherman in Meilian Village, Yazhou District, Sanya, provided a blurry video in which a group of Chinese white dolphins could be faintly identified swimming in a group.
Why are you so excited? Because this video is likely to break the academic understanding: China's southeast coast, south to the Beibu Gulf coast of Guangxi, north to the Yangtze River estuary, is the world's most important Chinese white dolphin habitat. Previously, academic circles and conservation circles generally believed that due to the potential impact of the natural deep-water barrier in the Qiongzhou Strait, there may be no Distribution of Chinese White Dolphins in the waters around Hainan Island.
So, will there really be Chinese white dolphins in Hainan? Everything needs to be supported by evidence. Since 2014, Li Songhai's team has continued to conduct maritime expeditions in the southwestern waters of Hainan Island.
The reality is harsh. There is no obvious law in the presence of Chinese white dolphins in Hainan, and the expedition team members do not have professional research vessels, and they can only use fishing boats to go to sea. However, after half a year and many sea expeditions, not even half a shadow of a dolphin was found.
When everyone had some emotions in their hearts, Li Songhai chose to lead the team to set off again. On October 20, 2014, the boat traveled to the waters of Sanya Yazhou Bay, and the surprise suddenly arrived.
"Ah, white dolphins!" shouted Lin Mingli, and the people on the boat invariably looked at the sea about 30 meters south of the bow, and more than 20 Chinese white dolphins were playing on the sea, jumping, floating, diving, full of vitality. After the reaction, taking photos, videos, recording behavior data, and collecting environmental factors related to the sea area, everyone quickly got busy.
The surprise of the first discovery of the Chinese white dolphin has not yet dissipated, and the next day out to sea, the researchers and the Chinese white dolphin have encountered unexpectedly. "Between October and December 2014, we conducted a 13-day sea expedition in the southwest waters of Hainan Island, and for 6 days we observed a population of Chinese white dolphins, and we could see Chinese white dolphins about every other day. The size of the group generally ranges from 10 to 40 heads, including individuals of different ages, and gray 'baby dolphins' can often be seen as long as adult dolphins. Li Songhai said.
The scientific expedition of Li Songhai's team found that the geographical distribution range of the previously known Chinese white dolphin in China was pushed south by nearly 300 kilometers. Subsequently, the team published the research in the international academic journal Marine Biodiversity Records. Because of the extremely important ecological and conservation value of this species, the research results have aroused concern.
Evolved into a Hainan endemic species?
The population exceeds 200 heads, and there are obvious differentiation of behavioral signs, which has formed a unique geographical population
If the southwestern waters of Hainan Island are the tropical habitat of the newly discovered Chinese white dolphins, where did they originate? What is the population size? What are the characteristics of the population distribution... A series of unsolved mysteries have greatly stimulated the enthusiasm of researchers to explore.
Through the passive acoustic monitoring method, the researchers collected the acoustic data of 11 monitoring sites in the southwest sea of Hainan Island for several years, and also used ship-based ecological surveys, molecular genetics and other research techniques to conduct a series of research surveys on the population, unveiling the mystery of the Chinese white dolphin in Hainan little by little.
Triangular dorsal fin, hunchback-shaped when exiting the water, long mouth... After nearly 20 years of studying marine mammals, Li Songhai can quickly identify whether it is a Chinese white dolphin at a glance. However, the Chinese white dolphins in Hainan still enriched his cognition.
"The South China Sea is the largest sea area, the deepest water and the highest habitat complexity in China, and the fish resources are abundant, providing sufficient food for the growth of Chinese white dolphins." Unlike other waters, Chinese white dolphins prefer to live at the mouth of large rivers, and the distribution area of Chinese white dolphins in Hainan does not have large rivers and rivers, and has the characteristics of larger clusters, deeper water depth at the discovery site, and higher salinity and conductivity. Li Songhai revealed that the Chinese white dolphin in Hainan mainly lives in the southwest sea from Sanya Yazhou Bay to the mouth of the Changhua River, with a wide distribution range.
"Our research shows that there are obvious differences between the Chinese white dolphins in Hainan and the Chinese white dolphin populations in other seas in terms of morphology, vocal behavior and genetics, indicating that there may be a lack of communication between the Chinese white dolphins in Hainan and other Chinese white dolphin populations for a long time, and there is obvious differentiation." Li Songhai said that the Chinese white dolphin in Hainan has formed a unique geographical population, or subspecies, or even species, which is unique to Hainan, and its origin needs to be further studied.
What new characteristics do the Chinese white dolphins living in Hainan differentiate? Lin Wenzhi, an associate researcher at the Institute of Deep-sea Sciences and Engineering of the Chinese Academy of Sciences and who has studied Chinese white dolphins in many places for 14 years, gave an example: "The skin of Chinese white dolphins is dark when they are young, and the skin gradually fades after adulthood until the old age is all white. According to our field observations, Hainan did not find a single all-white Chinese white dolphin. As a complete population, the Chinese white dolphins in Hainan cannot be without elderly individuals. This difference can only mean that the skin of the Chinese white dolphin in Hainan has a slower skin fading rate than other populations, so the skin color of the Hainan Chinese white dolphin seen is mainly gray and spotted individuals. ”
In the many field expeditions from October 2014 to the present, the most common thing researchers have done is to take "ID photos" for the Chinese white dolphins in Hainan. These photos are used by special personnel to compare with the photos in the database to confirm individual information.
"We can distinguish different individuals by the lack of different shapes of the posterior edge of the dolphin's dorsal fin in the photo, and the size and distribution of spots on the body. If there is a newly discovered individual, we will number it, name it, and add it to the database. Lin Wenzhi revealed that as of now, 201 Chinese white dolphins have entered the "archives" in the southwest waters of Hainan Island.
According to preliminary estimates, the global population of Chinese white dolphins is less than 13,000, and the number of populations in China's waters accounts for about half of the total population of Chinese white dolphins in the world. Data show that the population of Chinese white dolphins in the Pearl River Estuary-Hong Kong waters is the largest population of camel dolphins in the world, with about 2,000 to 3,000 heads. The population in the waters of Leizhou Bay in Zhanjiang is the second largest population of camel dolphins in the world, with about 1,000 heads.
"The population of Chinese white dolphins in the southwest waters of Hainan Island is greater than 200, and its number may rank third in China after the population of Chinese white dolphins in the Pearl River Estuary-Hong Kong waters and the Waters of Leizhou Bay in Zhanjiang." Li Songhai said.
Protection is in action
Hainan is expected to establish the province's first cetacean rescue base in Lingshui
In the cetacean herbarium of the Institute of Deep-sea Sciences and Engineering of the Chinese Academy of Sciences, the information of four Chinese white dolphin specimens that died stranded between 2015 and 2018 was recorded in detail. The more specific the time, place, body length, male and female information is marked, the more it reveals the pain of the researchers.
"Since dolphins are mammals, they need to breathe regularly on the surface of the water, and once they are entangled in ropes or nets, they are easily injured or even die. Noise can also lead to behavioral and physiological disturbances and damage to the echo localization system. In addition, fishery bycatch will have a serious impact on the survival of Chinese white dolphins. Lin Mingli said that as a near-shore marine animal, the activity area of the Chinese white dolphin overlaps with the human activity area and is highly susceptible to the influence of human activities.
There is no professional whale and dolphin rescue base, the lack of project support for basic scientific research, and the public's awareness of science protection is not strong, which further plagues the protection of Chinese white dolphins in Hainan.
"Although the population base of the Chinese white dolphin in Hainan may be good, scientific research and conservation are urgent." Li Songhai called for any change in the number of these top predators because the Chinese white dolphin is at the top or important link in the food chain of the offshore marine ecosystem, which will trigger a chain reaction throughout the offshore ecosystem, including affecting the offshore fishery resources and marine biodiversity, and ultimately affecting the human beings themselves. In addition, they also have important scientific research value in the fields of biology, bioacoustics, evolutionary biology, behavior, and biomimicry.
Relevant protective actions have been undertaken. China has set up 7 Chinese White Dolphin Nature Reserves, including 2 national nature reserves in Xiamen and Pearl River Estuary, as well as 1 provincial and 4 city and county nature reserves in Jiangmen, Shantou, Zhanjiang, Chaozhou and Raoping. In 2017, the Ministry of Agriculture and Rural Affairs organized the preparation of the "Chinese White Dolphin Conservation Action Plan (2017-2026)". In 2018, the Chinese White Dolphin Conservation Alliance designated the 23rd day of the third month of the lunar calendar as the "Chinese White Dolphin Conservation Publicity Day".
"Protecting the Chinese white dolphin is protecting the offshore ecosystem." Lin Wenzhi, who has worked in the Pearl River Estuary Chinese White Dolphin Nature Reserve for many years, suggested that Hainan can coordinate the establishment of the Chinese White Dolphin Nature Reserve in many ways, implement various protection policies, limit the intensity of marine fishery fishing and strictly implement protection and management measures such as seasonal fishing moratoriums, so as to achieve no decline in fishery resources and minimize shoreline changes.
So far, human research on small cetaceans such as chinese white dolphins has only been more than 40 years, and understanding is still limited. "It is proposed to establish the Hainan Chinese White Dolphin Research and Conservation Center in Sanya Yazhouwan Science and Technology City, with the Chinese White Dolphin in the southwest waters of Hainan Island as the main research object, increase funding and project support, and carry out in-depth research on the biology, ecology, behavior, genetics and conservation biology of the Hainan Chinese White Dolphin population, so as to provide a scientific basis for the formulation of effective protection and management measures for the Hainan unique Chinese white dolphin population." Li Songhai said.
"Last year, together with the research team, we formulated a five-year proposal for the Chinese White Dolphin Conservation Action Plan." The relevant person in charge of the Fishery Administration and Fisheries Supervision Department of the Provincial Department of Agriculture and Rural Affairs revealed that the proposal promotes the protection of this species by advocating the establishment of a multi-party protection mechanism, publicity and education to encourage public participation, and strengthening basic scientific research. Next, the Provincial Department of Agriculture and Rural Affairs will continue to cooperate with public welfare organizations to increase relevant training for fishermen, help them improve their basic rescue and treatment capabilities for marine animals, and learn to install marine animal escape devices for fishing nets to prevent accidental catch and accidental injury, and cooperate with relevant scientific research institutions to establish the first cetacean and dolphin rescue base in Lingshui.
"The meaning of life is to understand the world we live in, studying the Chinese white dolphin is a window for me to understand the world, and it is my job and mission to build a more promising future for this dolphin with the name of 'China'." This is Lin Wenzhi's hope, and it is also the dream of everyone who cares about the life of the ocean.
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Video: Institute of Deep Sea, Chinese Academy of Sciences
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