Dugongs are cute-looking, and they often live in the shallows of the coastline and feed on seaweed. In the larger image on the left, a dugong is eating seaweed. It survives in most of the world’s seas, most of which are in Australia. The small pictures on the right page show a dugong sculpture scenic spot in Thailand and the distribution of dugongs in the seas of the world. Dugongs have a docile personality and are endowed with a mysterious color by folklore, but they cannot escape the fate of being hunted and killed.
Recently, a piece of news has been frequently retweeted with the gimmick “Mermaids may disappear”. The content talks about dugongs being functionally extinct in Chinese waters. According to news reports, the last time dugongs appeared in China was 2008, and since then, there have been no sighting reports about it. According to historical data, the dugong population in China is rapidly collapsing. Combined with the habitat changes within its historical distribution range, the research team believes that the dugong population in the Chinese sea area has been unable to maintain self-sustainability.
Because the dugong is not a unique species in my country, this news did not “stir up a thousand waves with one stone” like the news of the extinction of the white sturgeon. However, on a global scale, “mermaids” may really be disappearing – in the past century, the global dugong population has continued to decline…
“Mermaid” prototype How much do you know about dugongs?
From “Shan Hai Jing” to “Shu Yi Zhi”, dugongs are described as unique sharks in the South China Sea, tears can be turned into pearls, and oil can last forever. In some dugong habitats in the southeast coast of my country and Southeast Asia, the tradition of anthropomorphizing dugongs in mythology is very common.
Dugongs are docile marine herbivores. The place where they live needs to meet many conditions, including moderate water temperature, suitable ocean currents, and good growth of their food—seagrass. Generally speaking, they mostly live in the seagrass near the coastline. They can enter the estuary with the tide to look for food, and after eating, they can return to the sea with the ebb tide. Dugongs live in “small families”, generally two or three of them live together. As mammals, they occasionally surface to breathe. When a female dugong nurses her young, she surfaces and holds her young in her arms, much like a human mother breastfeeds her young. When they are far away, fishermen and sailors mistakenly think that it is a woman breastfeeding a child. Gradually, dugongs have become the material of mermaid legends.
When a species is enigmatic, there are usually two outcomes. One is considered to have a special effect, to be used. For example, pangolins are believed to have miraculous effects of nourishing the body, which once attracted mass hunting. The other is regarded as auspicious or unlucky and is protected or taboo. For example, Indians usually do not kill oxen, because in their belief, oxen are god-like existences; while in some areas of China, weasels are regarded as “Huang Daxian” and are tabooed.
Both cognitions are reflected in dugongs. In the coastal areas of Vietnam, Thailand, Cambodia and other countries, people hunt dugongs, use its fat to extract oil, leather to make clothes, and bones to make artworks. They also hope that its meat can bring about the effect of “improving yang”. In ancient China, fishermen on the southeast coast regarded dugongs as “unlucky things”. If dugongs were accidentally caught in fishing nets, they would be released immediately. Will not deliberately kill.
With the progress of the times, people’s minds have been opened and liberated. Some superstitions and taboos have gradually been lost in the torrent of history, and dugongs have gradually become the target of fishermen. The first dugong research report in China was based on a dead dugong from the Beihai Seafood Market in Guangxi. It has been recorded that in order to solve the problem of food supply, the Shatian Commune in Hepu County, Guangxi once organized a hunt for dugongs, killing a total of 216 dugongs in a few years, which brought great damage and threats to the dugong resources in the Beibu Gulf. The population of Sha Tin is not large, and many residents are able to feast on dugong meat. Many of the elderly in Sha Tin today can recall its unique taste between pork and beef.
In the 1970s, a scientific research team came to Shatian to try to capture some dugongs for research, but the round-up process was the same as how fishermen hunted dugongs. Some dugongs died during the fishing process. In the end, 28 dugongs were captured, only Three survived, and the dead dugongs were cut up and sold to surrounding villagers. The surviving 3 dugongs eventually died in the local reservoir, and most of the follow-up studies were not completed. This fishing has made the already precarious dugong resources even worse. In 1984, another two dugongs were killed by a soil gun to fry fish. After the incident was reported by the media, it finally aroused heated discussions in the society. In 1989, dugong was listed as a national first-class protected animal. In 1992, the reserve was upgraded to a national nature reserve, and China’s dugong protection work was officially launched.
Protecting fragile seagrass beds awaits the return of ‘mermaids’
Many people know that mangroves and coral reefs are the hallmarks of marine ecosystems, but they don’t understand the ecological role of seagrass beds as important as these two.
The seagrass bed itself is extremely fragile. The turbid seawater caused by an abnormal storm surge, the abnormal salinity of the offshore sea caused by an abnormal land precipitation, or the seawater pollution and direct encroachment pressure caused by human activities may all lead to its failure. Severely degraded.
The Dugong National Nature Reserve in Hepu, Guangxi is the sea area most suitable for the growth of seagrass. Regrettably, although the level of protected areas has been upgraded and expanded, dugongs are still hard to find. Mr. Wang Pilie, a leader in marine mammal research in my country, once said with concern that the number of dugongs in the Beibu Gulf has been in a “sharply reduced” state. In the research report at the initial stage of the operation of the reserve, no traces of dugongs were found at all. In 2000, Nanjing Normal University organized three consecutive inspections in the Hepu Reserve. Although no traces of dugongs were found, they found the root of the problem, which is the degradation of seagrass beds.
According to the memories of the local elders, this area used to look like “seagrass contiguous” and “seagrass can lift people up”. However, the seagrass bed in Hepu has been seriously degraded now. There are 7 large grasslands within the protected area. In 1994, it was 400 hectares. In 2000, it became 364 hectares. Today, it has been reduced to only 80 hectares. The seagrass beds in Yingluo Harbor in Hepu are in danger of disappearing completely.
Not only in the Hepu National Nature Reserve, but also in the Bohai Sea to the South my country Sea, most of the once-prosperous seagrass beds have disappeared. This has directly affected the survival of many marine organisms, which are extremely dependent on seagrass beds. In Rongcheng City, Weihai, Shandong, the degradation of seagrass beds once made whooper swans give up this crucial wintering place; in Jiaozhou Bay, Qingdao, the decline of seagrass beds not only made it difficult for the local proud special dwelling “seagrass house”, It directly affects the breeding scale of fish.
Dugongs are strict herbivores—making them one of the most dependent marine animals on seagrass beds. Dugongs in East Asia and Southeast Asia prefer to eat Diyeria pinnata and Japanese eelgrass that grow on submarine sandbars. Adult dugongs consume a huge amount of food, and a dugong needs to eat a large area of seagrass every day. To maintain dugong populations living in a certain sea area for a long time, continuous seagrass beds are very important. The degradation of seagrass beds will inevitably lead to the disappearance of dugongs.
In Japan, dugongs are also known as “natural monuments”. In March 2019, the Fisheries Association of Okinawa, Japan issued a statement saying that a dead marine creature floating on the sea was found near the tidal embankment of the fishing port in northern Okinawa Prefecture. , After investigation by the staff of the local aquarium, it was confirmed that it was the body of a dugong. Japanese media also reported that there were originally 3 dugongs living near Okinawa, except for this dead dugong, the other 2 were also missing. Many people believe that the death of this dugong is inseparable from the Japanese government’s land reclamation project.
This is a project that started at the end of 2018. The Japanese government poured sand into the planned area along the coast of the Henoko area to reclaim land from the sea. As the sand in the sea continued to accumulate, the originally blue water in this area became muddy and dirty, which aroused strong protests from many people. There have been many local residents’ rallies in an attempt to obstruct the project. On the day when the reclamation project started, Danny Tamaki, then governor of Okinawa Prefecture, posted a video on the Internet, saying that the Japanese government’s land reclamation project in the Henoko Oura Bay area made him very sad. You should know that Dapu Bay is a rare and precious sea area in the world, which breeds more than 5,000 species of organisms, as well as the largest blue coral in the northern hemisphere. The Japanese government’s land reclamation will undoubtedly cause great damage to the marine ecology here.
In fact, the global population of dugongs has continued to decline over the past century. The direct cause of this decline is that the global seagrass bed is shrinking at a rate of 7% per year.
”Functional extinction” is the wake-up call sounded by the scientific community. However, functional extinction cannot be equated with “complete disappearance of species”. Crested ibises were once declared functionally extinct, but after being rescued and cultivated by people, they can still be seen flying in the sky.
Because dugongs are docile, they can get along well with humans. In the big picture on the left page, a dugong looks at the camera with a cute expression; on the right page, people in diving suits are diving into the seabed with the dugong. In the bottom picture on the right page, the sun shines through the sea into the seabed, which is the hometown of dugongs.
Dugongs also have a strong ability to migrate. They are semi-nomadic herd animals and often travel long distances in search of food. Studies from the Cocos Islands and the Great Barrier Reef have found that dugongs can migrate over 600 kilometers. It also suggests that dugongs may return if suitable habitat for them is restored.
The good news is that restoration of seagrass beds in China is ongoing. In May 2021, my country’s first “subtropical seagrass bed restoration joint laboratory” was established in the Hepu Dugong Reserve. The laboratory cooperates with the “State Key Laboratory of South China Sea Resource Utilization” of Hainan University to focus on solving the problems of seagrass breeding and seagrass bed restoration. At the same time, the “Seagrass Bed Restoration Work in Rongcheng, Shandong Province” led by Ocean University of China has restored nearly 400 hectares of Japanese eelgrass beds, so Rongcheng Swan Lake has regained its former prosperity.
Restoring the water plant beds is not a job that can be completed overnight. We still have a long way to go to restore the water plant beds to their original state, but we have been working hard in this direction, and we have hope that the “mermaid” returning home is not a fantasy.