Why Are the White Dolphins, Often Seen in the News, Becoming Increasingly Rare? - Huxiu#
#Omnivore
Why Are the White Dolphins, Often Seen in the News, Becoming Increasingly Rare?#
China is the country with the largest distribution of white dolphins in the world, but the population of white dolphins is gradually decreasing. The white dolphin is a coastal species found in estuaries and brackish waters in China. Researchers use dorsal fin photo identification technology to recognize and track individual white dolphins to understand their ecological habits and population status.
• 🐬 White dolphins can change color, transitioning from black to gray, then to pink, and finally to white as they age.
• 🐠 White dolphins prefer to eat mid-to-upper level fish, such as mullet and mackerel, and they have unique hunting strategies.
• 📸 Researchers use dorsal fin photo identification technology to identify individual white dolphins to collect data and carry out conservation work.
Good afternoon, everyone. My name is Zheng Ruiqiang, and I come from a local public welfare organization called Hainan Smart Fishing. Over the past 14 years, I have changed jobs five times, but three things have remained constant: my family, my cat, and the Chinese white dolphin.
Many people may not recognize or have seen a white dolphin; when it is in the sea, it looks like this, white and pink.
In 2018, I took this photo on Dajin Island in Jiangmen, which is on the west side of the Greater Bay Area.
This is the best photo I have ever taken in my life. Later, I named it "Unadorned," just like the beauty of nature.
One fascinating aspect of white dolphins is that they can change color. When dolphins are born, they are small, less than 70 centimeters; they are black, serving as camouflage in the sea.
By the age of three or four, they turn gray, with some white or black spots. At this time, their body length may only be three-quarters of that of an adult dolphin.
By the age of nine or ten, they reach sub-adulthood and start to show noticeable pink coloration.
By their twenties or thirties, dolphins slowly age, turning completely white, resembling the transformation from a ugly duckling to a beautiful swan.
Looking closely at this photo, you will find it is an elderly dolphin, around 30 years old.
White dolphins can live up to 50 years. You will find that they become more beautiful as they age.
At the end of 2020, due to the pandemic, I left university and went to work at my current public welfare organization.
▲ Going out to sea. Source: Tao Xing
I spent almost 50,000 yuan to buy a camera body. All my friends said, "Are you crazy?" That was half of the prize money from a public welfare competition. My teammates gave me tremendous support. There were five of us in total, and they shared half of it with me.
One day in 2021, when I was in Sanniang Bay, Guangxi, and took this photo at sunset over the sea, I felt that the tens of thousands of yuan were worth it.
White dolphins are also called "Mazu Fish," the embodiment of the ocean goddess. So in that moment, I captured a marine goddess! Next to it was a "Little Prince," which is this little dolphin.
When the sunlight hits their faces, it feels just like the feeling of first love in youth.
White dolphins are right beside us
Many people may feel that white dolphins are far away from us. But that's not the case.
China is the country with the largest distribution of white dolphins in the world, with about 4,000 individuals, accounting for more than half of the total white dolphin population worldwide. In the Greater Bay Area, there are over 2,500 white dolphins, with 914 in Jiangmen alone.
White dolphins are a coastal species found in estuaries and brackish waters. We can find them from the Yangtze River southward, from the Jiulong River estuary to the Pearl River estuary, all the way to Zhanjiang's Leizhou Bay, to the Nandu River estuary and the Dafeng River estuary in Guangxi, including Hainan.
They are a resident species, just like us humans, white dolphins also have their homes. They stay where they were born until they grow old and die.
In China, there are known to be 11 white dolphin populations: including Ningde and Quanzhou-Xiamen-Taiwan Kinmen in Fujian, Dongshan Island in Zhangzhou; Chaoshan, Shanwei, the Greater Bay Area, and Zhanjiang Leizhou Bay in Guangdong; Beihai Shatian and Qinzhou Sanniang Bay in Guangxi; the west coast of Hainan; and the west coast of Taiwan.
▲ The red-marked areas on the map indicate the distribution of white dolphins. Source: Chen Bingyao (2018)
The largest population is in the Greater Bay Area, previously known as the Pearl River estuary; the second-largest population in the world is in Zhanjiang's Leizhou Bay.
I personally study three relatively small populations. I am from Chaoshan, which you might have guessed. I often go to the population in Eastern Guangdong; I also go to Xiamen, where there is a slightly larger white dolphin population than in Shantou. I also visit Sanniang Bay in Guangxi.
Why do they choose these places as habitats? It’s actually similar to humans; we go to different places for two main reasons: to find food and to find partners. For white dolphins, the reasons are quite simple—resource selection and mate selection.
To nurture young dolphins, female dolphins expend more energy, so they go to areas where food is most abundant, such as estuaries, where the fish they eat are distributed.
Male dolphins, on the other hand, have a very simple goal: they want to eat more, get stronger, and then find more partners.
Often, we see that wherever female dolphins are, male dolphins will follow; especially when food is most abundant, which is around the fishing moratorium each year.
Like humans, white dolphins are also social animals. They have their own social networks, with friends they like, those they dislike, and those they absolutely do not want to be with.
Interestingly, we have also found that some female dolphins stay close to their mothers even after birth and into adulthood. The probability of them staying with their mothers is much higher than that of male dolphins.
What do white dolphins eat?
For white dolphins, the two most important things are survival and reproduction. These are the two most crucial keywords in animal behavior.
Let’s talk about what they eat.
In 2012, we rescued a Chinese white dolphin in Foshan. After returning from Foshan to Zhuhai, the first thing to solve that day was to figure out what the dolphin actually eats.
I remember that night until three or four in the morning, I couldn’t figure out what to feed it. The next morning, we went to the market and bought every type of fish that humans eat, but it wouldn’t eat any of it.
At that time, we had been at sea for over a year, and we thought about what fish we had seen at sea. So we went to buy.
One day, we bought some small fish that people don’t eat, and that night when we fed it, it ate. I was particularly happy when I returned from the market that morning. I had never been so happy seeing someone eat before.
Later, we discovered that white dolphins are not vegetarians. They prefer to eat mid-to-upper level fish, such as mullet, which people in the Pearl River estuary call "Xianzi" or "Qinglin." Another type of fish is mackerel, which belongs to the herring family, long and flat.
▲ Fish preferred by white dolphins
We even did something particularly funny: we cut other fish into shapes similar to these two types of fish. It ate them!
White dolphins have sharp teeth, so when eating fish, they do not chew but swallow. They bite the food and swim forward, swallowing it whole.
At sea, we sometimes see them catch fish that are too big and long to swallow in one bite. What do they do? They shake and shake, breaking the fish into pieces.
Of course, many times they still can’t eat it. I remember earlier this year when I was at sea in Fujian, I found a five or six-pound grouper, which was definitely left by a dolphin, but in the end, the captain took it and cooked it.
Unique hunting strategies
White dolphins have their unique hunting strategies. They are opportunistic and will follow fishing boats to catch fish.
▲ White dolphins follow fishing nets, preying on fish that escape the net. Source: Yan Yang (Greater Bay Area, 2019)
For example, at the Pearl River estuary, we can see "double towing," where white dolphins follow behind the net to eat fish that escape.
You might worry that they could get caught in the fishing nets. They are not as foolish as people think; they are actually very, very smart, much smarter than Yangtze River dolphins. So we have rarely seen dolphins accidentally caught in nets.
White dolphins are not just opportunistic; they also have unique hunting strategies. Different populations, ages, sexes, and even individuals have their unique hunting methods.
Like the dolphin in the picture, it looks like it is dancing ballet in the sea.
This is a young dolphin. It is still practicing how to catch fish, having spent almost half an hour without catching any, but it will eventually catch one someday.
Many people do not know that white dolphins cooperate in hunting, including myself. In 2022, I went to Sanniang Bay in Qinzhou with a reporter from Southern Weekend, Daming. We witnessed dolphins hunting together.
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▲ Source: Zhao Ming (Qinzhou, 2022)
In that moment, I seemed to see the future of my work: only by protecting fishery resources can we witness such scenes.
How do white dolphins reproduce?
After discussing their diet, let’s talk about the lifelong matter—reproduction.
Dolphin reproductive behavior is similar to that of other dolphins, which is promiscuous. Sometimes a female dolphin will have many male dolphins around her, but ultimately she will choose the one that can help her produce the best offspring.
White dolphins also exhibit a very special behavior that many people may not have heard of, called infanticide, where male dolphins kill young dolphins.
Why does this happen? I wonder if you have heard of a popular science bestseller called "The Selfish Gene"? The infanticide behavior of white dolphins is similar to the descriptions in this book: whether male or female, they hope their genes can be inherited by more offspring.
So for male dolphins, what they need to do is find more partners. They will always flirt around just to pass on their genes to more offspring.
▲ Adult male dolphins harassing female dolphins, killing young dolphins.
But for female dolphins, they can only give birth to one calf approximately every four years. Who the father is does not matter; what matters is that during these four years, they must ensure the survival of their offspring. So dolphin mothers will do everything they can to protect their young dolphins.
In the wild, we often see male dolphins forming groups to seek, harass, or even kidnap female dolphins, especially those mothers with newly born calves. Female dolphins will form "female alliances" to resist sexual harassment, thereby better protecting their young dolphins.
▲ Two male dolphins harassing and surrounding a mother and calf, with the mother dolphin being bitten and injured. Source: Lin Wenzhi (Pearl River estuary, 2011)
When outnumbered, you can see a dolphin mother carrying a dead calf, with the calf reduced to just a skin, and the dolphin mother may carry it for several days, swimming in the sea, never leaving it behind.
▲ Dolphin mother carrying a dead calf. Source: Zhao Ming (Qinzhou, 2022)
How to identify individual white dolphins?
After discussing animal behavior, let’s talk about myself. Many people say I am a dolphin photographer. In fact, my true identity is a data collector using dorsal fin photo identification.
This is the scene of my work, located in Jiangmen, Greater Bay Area.
We take a speedboat to find white dolphins. We try to minimize the disturbance to the dolphins from the boat while respecting animal etiquette, slowly approaching them from the side and rear, and taking photos with our cameras.
In fact, we do not recognize white dolphins by their faces but by their dorsal fins. Dorsal fin identification is similar to human facial recognition; the left and right sides of the dorsal fin are akin to the left and right sides of a human face. This way, each dolphin can form its own identification card.
Thus, we need to collect a large amount of data at sea. We often say "girls change a lot," and white dolphins change quickly too. So we need to design appropriate sampling intervals to track these dolphins over the long term, especially the newly born or young individuals.
Photo identification can also help us collect information about the dolphins' sex, kinship, injuries, diseases, and even threats.
▲ Dorsal fin photo identification can help us collect information about dolphins
For example, if we capture a photo of its reproductive slit, we can determine its sex; if we capture it giving birth, we can understand its kinship; if we capture its good friends, we can learn about its social unit; and injuries, diseases, and human activity disturbances can also be observed in this way.
The white dolphins I know
My research mainly focuses on three small populations—Shantou, Xiamen-Kinmen waters, and Sanniang Bay. Each population has some individuals that leave a deep impression on me.
- Strong Dolphin, ID A0018
The first individual I want to share lives in Sanniang Bay, Qinzhou, Guangxi. We call it "Strong Dolphin," with the ID A0018.
▲ The individual with pink spots in the back is "Strong Dolphin"
As early as around 2004, Professor Qin Dagong from Peking University saw this dolphin. He later told me that he saw a dolphin entangled in a gill net, covered in wounds and bleeding.
In 2017, when I first went to Sanniang Bay for photo identification, I captured this individual. Later, I took an even better photo and sent it to Professor Qin. He told me, "Look, how resilient life is!"
What surprised me even more is that over the past 20 years, it has given birth to at least three offspring. The youngest individual is still alive.
▲ Strong Dolphin and her calf
If you look closely, you will see that this young dolphin's dorsal fin is also injured. And like its mother, its injury is likely caused by fishing activities.
In our database over the past decade, the young dolphins that Strong Dolphin has raised, including those in her female alliance, are almost all scarred.
▲ The scarred family of Strong Dolphin
- Uncle Liang, ID A0008
This photo is the most beautiful one I have taken of a white dolphin in Chaoshan, taken in August this year.
The main character is not the one in front but the one behind. It is called "Uncle Liang," with the ID A0008. You will find that, like Strong Dolphin, its dorsal fin is also deformed, likely due to fishing activities.
Why is it called Uncle Liang? Because the first captain I went to sea with in Shantou was called Uncle Liang. He told me that he had seen it 20 years ago when he first started fishing, and it looked just like this.
We generally name white dolphins after people around us. But later we found out that Uncle Liang is actually female.
In 2018, I photographed the only newborn white dolphin in the entire Eastern Guangdong region at Shantou Port. I was particularly excited and named it "Lucky Star," after my good friend Wu Fuxing.
▲ Uncle Liang and Lucky Star
Unfortunately, it died a week later. I held back for a month without telling my good friend.
In the wild, the survival rate of white dolphin calves is less than 20%. We often see young dolphins dying shortly after birth. Moreover, for small populations, the mortality rate is even higher.
Another reason for the high mortality rate of young dolphins in the wild is that in places like Shantou, the population numbers are very low and relatively isolated, leading to inbreeding; the most direct consequence is that their entire spine is deformed and no longer streamlined.
▲ Spinal deformities caused by population isolation and inbreeding
What’s even more heartbreaking is that due to land reclamation, port construction, aquaculture, and high-density fishing, there are currently only 12 white dolphins left in the entire Eastern Guangdong region.
▲ The Eastern Guangdong population will go extinct in one generation, with gray indicating deceased individuals.
- Broken Jaw, ID EA0021
The third small population is the Xiamen-Kinmen population, mainly distributed in the coastal waters around Xiamen, Kinmen, and Quanzhou. In 2010, Dr. Wu Fuxing encountered this individual and was astonished.
We did not name this individual because we could not find a real person who looks like it—it has no upper jaw.
In 2020, when I went to Weitou Bay in Quanzhou and saw it, I was very surprised. Because after 10 years, it was still alive and well.
Earlier this year, in Weitou Bay, Quanzhou, we saw it again and discovered it was accompanied by a young dolphin, foraging in the corners of land reclamation and high-density aquaculture. Life is truly resilient beyond imagination!
▲ The area around the base is almost entirely oyster farming, with white dolphins surviving in the gaps
What factors threaten the survival of the Chinese white dolphin?
After so many years of research, I often ask myself: what exactly threatens the survival of the Chinese white dolphin?
In fact, almost all populations face three main threats.
First, habitat degradation. For example, land reclamation, coastal construction, marine engineering, and nearshore aquaculture occupy the habitats of white dolphins; the discharge of land-based pollutants also directly leads to a decline in habitat quality.
Second, human activity disturbances. Overfishing, maritime traffic, unregulated dolphin-watching tourism, and the fishing activities mentioned earlier all interfere with the selection of animal habitats and affect their behavior.
Third, population isolation. Historically, the distribution of white dolphin populations along China's coast has been continuous from south to north. However, due to the development of agriculture, fisheries, and urbanization, habitats have become fragmented, affecting gene exchange between different populations and increasing the likelihood of inbreeding.
What are the consequences of these threats?
The most direct consequence is that—the largest population of white dolphins in the world, the Greater Bay Area/Pearl River estuary population, is declining at a rate of 2.5% per year; the Eastern Guangdong population has decreased by 30% over the past 10 years; and the Sanniang Bay population in Qinzhou has decreased by 35% in the past five years.
Internationally, it is believed that if the number of coastal cetaceans falls below 100, then all conservation measures will be unable to reverse their extinction trend.
Why is there such a large gap between public perception and reality?
I want to ask, are you aware of these crises? Do the general public know? We often see in the media that when dolphins appear, the ecological environment has improved. But has the ecological environment really improved? No, only the mobile phones have improved.
In fact, there is not a single white dolphin population in the world that is increasing. So we might ask: why is there such a gap between public perception and reality? Where is the discrepancy between media information and research data?
Over five years, through field photo identification and data collaboration, we discovered:
Much of the data reported by the media is this blue line—the cumulative number discovered, which indicates how many dolphins are born each year. Since dolphins don’t shrink back after being born, this number will always rise.
Between 2015 and 2019, we compiled all the data we could find and conducted photo identification, forming this green line—during the rising period, as time passed, the number of dolphins we identified increased, and the data rose.
When our research covered most dolphins and reached a plateau, the trend stabilized; during the fluctuation period, the number of dolphins you see each year can truly reflect its population fluctuations.
We used mathematical models, represented by this red line, to analyze the size of this population, calculating for the first time that the Sanniang Bay population decreased from 156 individuals in 2015 to 102 in 2019, a reduction of 35% over five years.
▲ Source: https://www.frontiersin.org/articles/10.3389/fmars.2022.782680/full
This data is nearly 300 individuals lower than the media-reported figure of around 400. So what caused this information gap?
We found that the reason is the lack of transparency and continuity in the data. Precisely because of this, the public's perception and the decision-making of management agencies have lagged behind. Ultimately, this may lead us to miss the window of opportunity, missing the best time for rescue.
What exactly have we protected?
Thus, it can be seen that the protection of white dolphins is not just a simple scientific research issue.
Sometimes I also ask myself, after more than a decade, it seems I haven’t accomplished much. I also wonder, as researchers, have we considered the efficiency of conservation? We have invested so much money, so many people, and spent so much time—what exactly have we protected?
We also need to consider another question: the interests of the community, fishermen, aquaculturists, dolphin-watching practitioners, and those living in remote areas—should they be taken into account?
And animal welfare. Are dolphins living well? Are they happy? Are they really smiling, or is their smile just a facade?
We may need to truly consider this: what kind of welfare have we achieved for animals? What have we done ourselves?
This is a white dolphin from my hometown, with the beautiful Nanao Bridge in the background, isn’t it lovely?
But if I tell you that there are only 12 Chinese white dolphins left in the entire Eastern Guangdong sea area; that within the next 20 years, the entire population will disappear, how would you feel?
I am from Chaoshan. The next generation of Chaoshan people, including my children, will not be able to see them. That is the only white dolphin population. The only one.
I wonder if you remember that just recently, on November 6, a Chinese white dolphin stranded at the Guangzhou Pearl River Bridge.
On November 13, a reporter from Southern Metropolis Daily told me that the dolphin had died, and it was in the public eye for a shorter time than Lucky Star was alive.
I believe for the vast majority of people, this is just news; for researchers, including myself, it is a record of stranding, a data sample; but for the entire Greater Bay Area population, it is an important member, a life.
So when I joined a public welfare organization and started incubating my public welfare projects, I thought: how can I make more people treat every Chinese white dolphin like they treat every person and every life around them?
Building a digital ID for every white dolphin
In 2021, we made our first attempt—to analyze all data from three small populations using AI technology. We can identify which white dolphin it is in about 11 seconds, just like facial recognition.
Of course, its accuracy is not yet 100%, as we only received 20,000 yuan for development costs, but at least it can identify over 90% of dolphins.
In 2022, we also received significant help from Tencent Charity. Other domestic foundations working on biodiversity, including Zhilan, also provided us with assistance.
We continue to collect data and consider how to make the data come alive, allowing more people to use it. Thus, we utilized internet technology to create a digital application, which has a mini-program and a webpage called iDolphin.
▲ iDolphin
We have achieved individual identification of 2,696 Chinese white dolphins over 14 years across five populations. You can see all the data for each dolphin.
We also implemented some technical measures to protect copyrights and ensure data security. Within the framework of data collaboration, we aim to make this data better serve different groups.
We hope to establish white dolphin identification cards, combining internet charity with data transparency, using a crowdsourced conservation approach, where those with money contribute money, those with strength contribute strength, and those with heart, love, and technology can all participate. We hope everyone can join in their own way.
You can become a "fan" of white dolphins, forming a "dolphin friend circle." You can name a dolphin or adopt one. You can even become our volunteer and go out to sea with us, as long as you have the time.
▲ In 2012, Zheng Ruiqiang rescued a lost dolphin in a waterway in Foshan
We hope to use this approach to encourage more people to treat a dolphin like a life, to know it, to understand it, to respect it, and to protect the largest population of white dolphins in the world around us.
After 14 years of research on white dolphins, I have only understood one very simple truth: the courage of a society does not lie in how much we are willing to pay for success, but in whether you are still willing to do this when you realize there is a possibility of failure.
The protection of white dolphins requires the courage of our entire society, and we need to be willing to face the cold truth behind the data.
In the end, these small populations may still leave us, but only if we are willing to confront this truth can we take more ambitious conservation actions. Only then can humanity better face the global biodiversity crisis.
That concludes my speech. Thank you all for listening. May white dolphins thrive, and may we have abundance year after year.