The Yangtze River has entered a ten-year fishing ban, but the Chinese sturgeon can no longer wait...

On July 21, 2022, the World Conservation Union (IUCN) released the latest red list of species. In the list, the white sturgeon was officially declared extinct , and all 26 existing sturgeon species in the world are facing the risk of extinction.

Many people were saddened by this tragic news. Many people had never even seen a white sturgeon. The first time they heard about it, they had already seen it forever. More than two years ago, Dr. Wei Qiwei, a famous sturgeon expert, chief scientist and researcher at the Yangtze River Fisheries Research Institute of the Chinese Academy of Fishery Sciences, predicted in an academic paper that the Yangtze River white sturgeon had become extinct as early as 2005-2010 .

White sturgeon specimen｜Little yellow chicken

The giant fish has a long snout like a sword

The white sturgeon (Psephurus gladius) is a large carnivorous fish that lives in the Yangtze River. It belongs to the genus Acipenser in the family Acipenser in the order Acipenseriformes. It is one of the only two surviving fish in this family and is also endemic to China .

Chinese stump commemorative stamps issued by China Post｜amazon.com

The North American sturgeon (Acipenser transmontanus) is sometimes called the "white sturgeon" because of its body color, which leads to confusion. In fact, there are great differences in the morphology of the two sturgeons:

The white sturgeon has a long head and an extremely elongated snout , with the head being more than half the length of the body. People living along the Yangtze River in the past observed this feature of the white sturgeon and called it elephant fish (Sichuan), swordfish (Hunan), etc. The Chinese sturgeon does not have these features.

In addition, the white sturgeon is fusiform and long, with a dark gray body surface and no scales. There is only a row of about 8 spiny hard scales on the upper lobe of the tail fin; while the Chinese sturgeon is covered with five rows of bony hard scales.

White sturgeon. Unfortunately, we can't even find a few clear photos of the white sturgeon｜Wikimedia

Acipenser truncatus｜Cliff / Wikimedia

The sword-like snout plays a vital role in the life of the white sturgeon. Due to the turbulent water flow and dim light at the bottom of the Yangtze River, the white sturgeon's eyes have become very small and its vision is very poor, but on its long snout and head, there are clusters of dense, plum-shaped skin receptors - pits and Lorentzian organs. The former is responsible for mechanical perception , such as changes in water flow and water pressure, while the latter is responsible for electrical perception , such as weak low voltage in the water.

In this way, the white sturgeon is like carrying a long scanner, which can easily sense various changes in the surrounding environment.

Where is the former king tuna now?

In ancient times, the large white sturgeon was once distributed in major rivers in China , and was also distributed in North China and the coastal areas. The " tuna " in the poem "There are tuna [wěi] and tuna [xún]" in the Book of Songs refers to the white sturgeon.

In the records of the Zhou emperor's spring sacrifices to the ancestral temple in the Book of Rites and the Book of Zhou Rites, there is a description of "the emperor began to ride a boat and offer tuna to the temple", which is similar to the time when the white sturgeon migrates in groups. The white sturgeon is classified according to its size:

".……The particularly large ones are called king tuna ."

There is a saying among fishermen in Sichuan: "A thousand catties of Lazi weighs as much as ten thousand catties of Xiang, and Huangpai is too big to be worthy of its name." "Lazi" refers to the Chinese sturgeon, which is also on the verge of extinction, "Huangpai" is also an endangered fish, and "Xiang" refers to the white sturgeon.

This proverb indirectly reflects the huge size of the white sturgeon - in fact, they may be the largest freshwater fish ever seen by humans .

The Chinese sturgeon is classified as "critically endangered" by the IUCN. Some businesses sell "Chinese sturgeon" for consumption, but they are actually hybrid sturgeons.｜Wikimedia

In the past, the white sturgeons that people caught were mostly about 1.5 to 3 meters long and weighed up to 150 kilograms. According to the records of ichthyologist Mr. Bingzhi in the 1950s, a giant white sturgeon was caught in Nanjing, which was 7.5 meters long and weighed 908 kilograms. The huge body allows the white sturgeon to directly swallow the adults of large freshwater fish such as the four major carps.

Adult white sturgeons have no natural enemies. They stand at the top of the food chain and gallop across the Yangtze River from top to bottom. They are the well-deserved king of fish in the Yangtze River .

White sturgeon specimen｜Little yellow chicken

As a large migratory fish , the Chinese sturgeons swim upstream along the Yangtze River around the Qingming Festival every year, swimming upstream to the Yibin section of the river and the Jiang'an section of Sichuan Province to spawn. After the young sturgeons hatch, they migrate downstream in groups. As they grow, they gradually disperse and enter the tributaries and lakes of the Yangtze River Basin, and even the brackish waters of the Yangtze River estuary to forage and fatten.

The Yangtze River and its banks are home to many unique species, and this is also their final home｜Andrew Hitchcock / Wikimedia

The number of eggs carried by white sturgeons is very large. A 35kg individual can carry up to 200,000 eggs. Therefore, in the 1970s, the total annual catch of white sturgeons was still stable at around 25 tons . Fishing pressure has not had a serious impact on its population.

However, due to the emergence of new things on the Yangtze River - dams , the ecological balance of the Yangtze River has gradually been broken.

Large dams have a disastrous impact on migratory fish. On the one hand, the dams across the river block the fish's spawning route, dividing the fish and spawning grounds into two unconnected areas above and below the dam, further dispersing the already small number of white sturgeon groups and greatly reducing the area of ​​the spawning grounds ; on the other hand, the dam's water storage function also affects the Yangtze River's hydrological conditions such as water temperature and water depth to a certain extent, which in turn inhibits the gonadal development of migratory fish and other signs related to spawning to a certain extent.

Sometimes people build "fish ladders" on dams to make it easier for migrating fish to pass through the dam｜Qurren / Wikimedia

Since the dam was built, a large number of Chinese sturgeons and Chinese white sturgeons have gathered on both sides of the dam trying to pass through, but what awaits them is the ruthless fishing nets of humans. According to fishery data, the catch of Chinese white sturgeons and Chinese white sturgeons has increased significantly in those years.

However, greed comes at a price. While the Chinese sturgeon is facing a breeding dilemma, the higher fishing intensity than ever before is undoubtedly making things worse. In addition, the frequent shipping on the Yangtze River, as well as a series of factors such as sand mining and sewage discharge along the coast, the Chinese sturgeon is also facing multiple problems such as food shortages, destruction of spawning grounds, population fragmentation, and lack of migration routes. It can be said that it is surrounded by despair and it is difficult to find a way out.

Therefore, since 1985, the population of Chinese sturgeon has experienced a cliff-like decline .

Over the past few decades, the white sturgeon is not the only fish that has disappeared from the Yangtze River. Once upon a time, shad was a very common fish species in the Yangtze River, Qiantang River, Pearl River and Minjiang River systems. They migrated together in late spring and early summer every year to form a fishing season. But now, it is difficult to find shad on the market.｜Hugh Llewelyn / flickr

By 1994, Dr. Wei Qiwei had rescued four trapped white sturgeons. In the end, only one was successfully rescued and released back into the Yangtze River.

The last time the white sturgeon appeared was around January 23, 2003. After the white sturgeon was released into the Yangtze River with an ultrasonic tracker installed, the speedboat tracking it ran aground and caused a malfunction, resulting in the loss of signal, and the white sturgeon eventually disappeared.

To this day, scientific researchers have not discovered any white sturgeon , nor have any individuals been artificially bred.

In 2022, the white sturgeon was officially declared extinct in the IUCN Red List.

A white sturgeon captured in 1993 | Hui Zhang, et al. / Science of The Total Environment (2020)

In addition to the white sturgeon, all 26 species of sturgeon in the IUCN's updated red list are facing the risk of extinction - in 2009, this proportion was only 85%. For centuries, sturgeons have been overfished due to the demand for eating sturgeon meat and making caviar; even though they are protected, poaching still affects more than half of the sturgeons. Now, in the IUCN Red List of Species, there are 17 species of sturgeons in critically endangered status, 3 species in endangered status, and 5 species in vulnerable status.

We have lost the white sturgeon, but we have not lost the Yangtze River

However, the white sturgeon is not the only one facing difficulties brought about by environmental changes.

The wild population of Chinese sturgeon, also a migratory fish, is also in danger . There has been no record of reproduction for several years, and it relies on the annual release of artificial populations to barely survive. The bighead carp, also a large predatory fish, has not been seen for more than ten years , and only a color photo of it when it was alive remains. The shad, which is the top of the three fresh fish in the Yangtze River and is hated by literati for its many thorns, has also not been seen for many years and is suspected to be extinct (some say functionally extinct). In addition, the baiji dolphin, which was photographed swimming with fishing boats many times in the last century, was declared functionally extinct as early as the beginning of this century...

Baiji, known as the "Goddess of the Yangtze River". In 2002, Qiqi, the last artificially raised Baiji, died in the Baiji Pavilion of the Institute of Hydrobiology, Chinese Academy of Sciences. | IUCN red list

The skull of the mullet｜Young Hero Little Yellow Chicken

The consequences of unbridled overdrafting of the environment are far more than these. According to surveys, even the reproduction numbers of the four most common carps in the Yangtze River have dropped by as much as 90% .

The Yangtze River has paid a heavy environmental price for the rapid and extensive economic development model over the past few decades. More and more people have resorted to illegal methods such as "electric shock, poison and explosion" and "destroying nets" to catch as many fish as possible, which has eventually formed a vicious cycle of "the more you catch, the less resources you have, the worse the ecology is, and the poorer the fishermen are." The Yangtze River's biological integrity index has reached the worst level of "no fish."

To this end, Cao Wenxuan, a famous ichthyologist and academician of the Institute of Hydrobiology, Chinese Academy of Sciences, suggested changing the current phased fishing moratorium to a comprehensive fishing moratorium of ten years , "rescue protection" of China's largest aquatic biological resource pool, and restoring the ecology of the Yangtze River.

Why is there a ten-year fishing ban?

1. Overfishing is one of the main reasons for the sharp decline in freshwater fish resources, and it not only reduces the "stock" of fishery resources, but also seriously damages the "increment". For example, in Dongting Lake, which is connected to the Yangtze River, 91% of the fish caught by illegal fishing methods such as "maze fishing" are juvenile fish weighing less than 50 grams, and fish weighing more than 100 grams only account for 2% of the total catch.

2. Large and rare aquatic animals such as the Yangtze River dolphin and the Chinese sturgeon all feed on fish. If there is no fish in the Yangtze River, the most direct harm will be to these species at the top of the food chain. If no measures are taken, they may all disappear in 15 years.

3. The Yangtze River is a natural germplasm resource bank for the “four major carps” and can provide high-quality broodstock for artificial propagation and breeding. Restoring the natural ecosystem of wild fish in the Yangtze River is related to the development and future of freshwater aquaculture.

4. The current fishing ban system has natural defects. The three- to four-month annual fishing ban system implemented since 2002 has played a certain role in protecting fishery resources. However, the offspring of Yangtze River fish that reproduce naturally often have no time to grow up and are caught ashore after the three-month ban is lifted. The growth chain of fish is interrupted, and the original intention of the current fishing ban system is difficult to achieve.

In addition, the current artificial reproduction and release activities are often more formal than substantive, and the released fry may be caught soon, greatly reducing the actual effect. Moreover, the reproduction and release of some social groups also poses the risk of affecting or changing the genetic structure of fish populations.

Will this decade affect the fish that ordinary people eat? And what should fishermen do?

1. The main economic fish species in the Yangtze River, such as the four major carps, generally reach sexual maturity at 3 to 5 years old. A 10-year fishing ban will allow 2 to 3 generations of reproduction, which will help to restore the number of aquatic biological resources in the Yangtze River exponentially.

2. According to statistics from the national fishery department, in 2011, my country's freshwater aquatic product output was 26.9516 million tons, while the catch in the Yangtze River Basin was only 1.29 million tons. If only the mainstream of the Yangtze River is counted, the current natural catch has dropped to about 100,000 tons, even less than 0.5% of the total output.

3. As fishing income decreases year by year, the fishing industry can no longer support the basic livelihood of fishermen along the river. It is a general trend for fishermen to seek other ways out and switch to other industries. The state also has relevant policies to support fishermen in terms of livelihood security, economic subsidies, skills training, etc. after they retire from fishing and switch to other industries.

Although everyone knows that the white sturgeon has long been extinct, out of personal emotion, although I believe that the white sturgeon has become extinct, I still hope that there are still a few surviving individuals lurking under certain waters that will come out and slap me in the face. After all, there are precedents of species being rediscovered after being declared extinct.

Will the 10-year fishing ban be as effective as planned? I don’t know. We need to wait and see with hope to find the answers to all these questions.

Author: Shaoxia Little Yellow Chicken

This article comes from the Species Calendar, welcome to forward

If you need to reprint, please contact [email protected]