Are “mermaids” really functionally extinct in our country?

The dugong, the animal that inspired the mermaid story, is facing extinction in China, according to the BBC. What's going on?

In fact, what the foreign media quoted was a study recently published in "Royal Society Open Science". This study focused on dugongs along the coast of China. The number of dugongs in the world is still in the tens of thousands.

So today I will talk to you about the real situation of dugongs in our country from four aspects!

01. What is a dugong?

Dugong, pronounced as rú gèn, has a beautiful nickname: mermaid. Many people may think that this animal is connected with mermaid when seeing the photo of this creature, because it looks like a cow. Indeed, dugong has another name, called sea cow, and like cow, it eats grass, mainly marine grass, such as two medicine algae, salt-loving grass and other aquatic plants.

In fact, the dugong itself is a very docile animal. In my country, it lives in the coastal and estuary areas of our country. For example, areas such as Guangdong, Guangxi, Hainan and the southern coastal areas of Taiwan rarely go to the open sea, so dugongs are often observed. Shown below is the distribution map of dugongs in my country.

However, this also led to the crisis of dugongs. When people caught dugongs, they began to use them. Because dugongs have high fat content, they can be used to extract oil, their bones can be used to carve tools, and their leather can be used to make clothing, so dugongs have been hunted by humans.

The result is that the number of dugongs is decreasing. Although in 1996, my country established the Guangxi Zhuang Autonomous Region Hepu Dugong National Nature Reserve in the coastal waters between Yingluo and Dafengjiangkou in Beihai, Guangxi, this still failed to prevent the continued decline in the number of dugongs.

The declaration of functional extinction of dugongs is a signal worthy of attention.

02. Are dugongs really functionally extinct in China?

Professor Samuel Turvey from the Zoological Society of London (ZSL), who co-authored the study, said "the potential disappearance of the dugong in China is a devastating loss". Scientists from ZSL and the Chinese Academy of Sciences reviewed all historical data on previous dugong sightings in China. They found that scientists had not verified a sighting since 2000. In addition, the researchers turned to citizen science, interviewing 788 community members living in these coastal areas to determine when locals last saw a dugong. On average, residents reported that they had not seen a dugong in 23 years. Only three people had seen a dugong in the past five years. In 1988, the dugong was listed as a national first-class key protected animal by China, however, there have been no records of dugongs appearing in China since 2008. After investigation and research, scientists believe that the dugong is functionally extinct in China - meaning "it can no longer survive on its own."

03. What is functional extinction?

Functional extinction (Functional extinction/Functionally extinct) means that under natural conditions, the dugong population has been reduced to the point where it can no longer sustain reproduction. In layman's terms, although there are still dugongs, they are no longer able to reproduce and expand their population. If there is no other intervention, it is highly likely that dugongs will eventually go extinct.

Therefore, functionally extinct species are sometimes referred to as "zombie species."

Fortunately, dugongs still exist in other waters, such as the tropical and subtropical coastal and island waters of the Indian Ocean and Pacific Ocean, so the entire species is not yet endangered.

04. Controversy over the functional extinction of dugongs

Seeing that some comments are leading to another angle, I think I still need to say a few words.

First, here is our own article: Dugongs are functionally extinct in China

Through their research, they found that the number of dugongs began to decline rapidly after 1975, and was basically not recorded after 2008.

According to interviews with people, only three people have sighted dugongs in the past five years, and the average time a dugong was sighted was 23 years ago.

In other words, the number of dugongs is extremely small and the population has collapsed, so they are functionally extinct in my country. The author proposed that the functional extinction of dugongs in Chinese waters is the first functional extinction of large vertebrates in Chinese waters.

Secondly, although the dugong is a species distributed worldwide, it is also important to my country. For example, it is a first-class protected animal in the list of national key protected wild animals.

This shows that we are trying hard to protect them and have established protected areas, but we have not been able to prevent functional extinction.

Finally, as to why dugongs became extinct, there are currently multiple factors. One is hunting, and the other is seagrass degradation, which led to the collapse of their population. Overall, this may reflect the gradual ecological deterioration of the marine ecosystem in my country's waters.

Lin Mingli, Turvey Samuel T., Han Chouting, Huang Xiaoyu, Mazaris Antonios D., Liu Mingming, Ma Heidi, Yang Zixin, Tang Xiaoming and Li Songhai 2022Functional extinction of dugongs in ChinaR. Soc. open sci.9211994211994