Goodbye River Monsters: Scientists Declare Two of the World’s Larger Freshwater Fish Extinct

Chinese paddlefish in museum
© Alneth / CC BY-SA 4.0

Written by Colby Maxwell

Updated: March 25, 2023

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Key Points:
  • Contrary to popular belief, rivers also contain creatures capable of rivaling those that live in oceans in terms of size.
  • The Yangtze sturgeon, considered a living fossil, is now available only on breeding farms.
  • The Chinese paddlefish, which was one of the largest freshwater fishes on the planet, is, however, extinct.

Many of Earth’s greatest creatures became extinct once humans came along and began using them as a “resource.” Unfortunately, it happens more than we realize. Current estimates place biodiversity loss at around 150 unique species a day, a truly shocking number. Sadly, that trend continues, and two recent examples show it a little too well. Let’s discover the two river monsters that scientists have officially declared extinct.

Two of the World’s Largest Freshwater Fish Have Officially Been Declared Extinct

Goodbye River Monsters: Scientists Declare Two of the World's Larger Freshwater Fish Extinct

Both the Yangtze sturgeon and the Chinese paddlefish were declared extinct in 2022.

©Alneth / CC BY-SA 4.0 – Original / License

A “river monster” isn’t really what it sounds like at first. The expression was popularized by the show that shares the name, but it simply means a massive freshwater fish that lives in a river. We generally consider the ocean the home of large fish, but lurking beneath the rapids of some rivers are creatures that rival some of the larger fish in the oceans.

Among those “river monsters” are the Yangtze sturgeon and the Chinese paddlefish. These fish deemed “the last giants of the Yangtze,” have been officially declared extinct by scientists. These amazing fish have lived in the Yangtze River for a very long time, with some estimates placing the Yangtze sturgeon as a 140 million-year-old tenant. The Yangtze sturgeon was generally considered a living fossil (like many other sturgeons) and had the typical bony and elongated appearance that most surgeons share. The Chinese paddlefish was known for its long silver body and long snout with which it sensed prey.

The Yangtze sturgeon still has hope, albeit slim. There are some captive ones that are held in tanks and breeding programs around the region. So far, however, any attempts at placing these farmed fish into the wild have failed.

The paddlefish, sadly, has no future. There are no captive specimens, and no tissue samples were ever taken of this fish. As such, it is now permanently extinct.

What Caused the Yangtze Sturgeon and Chinese Paddlefish to Go Extinct?

Goodbye River Monsters: Scientists Declare Two of the World's Larger Freshwater Fish Extinct

The Three Gorges Dam is the largest dam in the world.

©isabel kendzior/

The fish have been living in the river for longer than humans have been around, but their sharp decline can be traced to the construction of the river’s first dam back in the 1980s. Once the dam was constructed, both fish began their decline. The Yangtze sturgeon had a migratory path that spanned from the East China Sea to where it spawned, just above the dam. The structure blocked the pathway for the fish, slowing reproduction. The Chinese paddlefish was last seen around the Three Gorges Dam in 2003, showing just how detrimental the dams were to native wildlife.

Aside from the damming, the fish were also the victims of overfishing. Ancient Chinese emperors considered the paddlefish a delicacy, while the caviar of the sturgeon was extremely valuable. Overfishing, combined with pollution and damming, were the final nails in the coffin for the last of the Yangtze river monsters.

All About the Yangtze Sturgeon

Specimen of a Yangtze sturgeon

Specimen of the Yangtze sturgeon, aka Chinese or Dabry’s sturgeon, which has been declared to be extinct in the wild

©CC BY-SA 4.0 – Original / License

How Big Was the Yangtze Sturgeon?

The Yangtze sturgeon is considered one of the larger freshwater fish in the world. They can reach lengths of up to 8.2 feet and are known to weigh upwards of 40 lbs.

Where Did the Yangtze Sturgeon Live?

The Yangtze sturgeon had a historical range that encompassed the entire Yangtze River basin. They are known to spawn in the upper regions of the basin and travel down toward the East China Sea.

What Did the Yangtze Sturgeon Eat?

These sturgeon are known as “benthic” predators, meaning that they mostly eat along the bottom. They are known to eat crustaceans, mollusks, small fish, and insects.

All About the Chinese Paddlefish

Goodbye River Monsters: Scientists Declare Two of the World's Larger Freshwater Fish Extinct

The Chinese paddlefish was one of the largest freshwater fish in the world.

©Alneth / CC BY-SA 4.0 – Original / License

How Big Was the Chinese Paddlefish?

The Chinese paddlefish was quite a bit larger than the sturgeon. They have been recorded up to 23 feet long and was recognized as one of the largest freshwater fish in the world. The maximum weight recorded was around 660 lbs.

Where Did the Chinese Paddlefish Live?

The Chinese paddlefish was found exclusively in the Yangtze River basin and the estuaries around the East China Sea. It would generally stay in the river but would also venture into lakes around the area.

What Did the Chinese Paddlefish Eat?

The Chinese paddlefish mostly ate other fish, namely anchovies, gobies, catfish, and even flounder. They also occasionally ate crabs and shrimp.

Endangered Freshwater Fish

The World Wildlife Foundation has stated that thousands of freshwater species are headed for extinction at a rate twice that of endangered forests. The situation is so bad that nearly one-third of all freshwater fish are threatened.

Since 1970, there has been a 94% decrease in mega fish (weighing over 66 lbs.), so we may soon have monster fish in legends only. Migratory freshwater fish have seen a 76% decline since 1970. In just one year recently–2020–16 freshwater fish species were added to a list of 64 others on the list of extinct species recorded by the International Union for Conservation of Nature.

Part of the reason for this decline is the crisis being experienced by freshwater ecosystems: in the last 50 years, 35% of wetlands have disappeared, and most of the world’s major rivers are no longer free-flowing; that is, they have been dammed up or have dried out.

This situation is not only tragic for the fish, but also for the 200 million people worldwide who rely on them for protein and the 60 million people who have jobs in the fishing industry.

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About the Author

Colby is a writer at A-Z Animals primarily covering outdoors, unique animal stories, and science news. Colby has been writing about science news and animals for five years and holds a bachelor's degree from SEU. A resident of NYC, you can find him camping, exploring, and telling everyone about what birds he saw at his local birdfeeder.

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