Chinese paddlefish facts for kids
Quick facts for kids Chinese paddlefish |
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| Preserved specimens at Museum of Hydrobiological Sciences, Institute of Hydrobiology, Wuhan, China | |
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The Chinese paddlefish (Psephurus gladius), also known as the Chinese swordfish, was a huge fish that once lived in the Yangtze River and Yellow River in China. It was one of the biggest freshwater fish in the world. Some records say it could grow over three metres (ten feet) long, and possibly even up to 7 m (23 ft)!
This amazing fish was the only species in its group, Psephurus. It was also one of only two types of paddlefish still alive until recently. The other is the American paddlefish. The Chinese paddlefish was an anadromous species. This means it lived part of its adult life in the sea. Then, it would swim up rivers to lay its eggs.
Sadly, the Chinese paddlefish was officially declared extinct in 2022. Scientists believe it likely disappeared around 2005, or no later than 2010. However, it had become functionally extinct (meaning too few to survive) by 1993. The main reasons for its extinction were the building of large dams, like the Gezhouba Dam and Three Gorges Dam. These dams blocked the fish's path to its spawning grounds. They also split up fish groups. Too much fishing also played a big part in its disappearance. People had been fishing for Chinese paddlefish for hundreds of years. By the 1970s, about 25 tons were caught each year.
Since the 1990s, the International Union for Conservation of Nature (IUCN) listed the species as critically endangered. The last time a live Chinese paddlefish was seen was in 2003. In 2019, scientists confirmed the species was extinct. The IUCN formally updated its status to "extinct" in July 2022.
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What Did the Chinese Paddlefish Look Like?
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The Chinese paddlefish had a white belly. Its back and head were grey. Its dorsal (top) and anal fins (bottom) were set far back on its body. It had a long, narrow, paddle-like snout called a rostrum. This snout could be a quarter to a third of its total body length. Its eyes were small and round. The tail fin was heterocercal. This means its spine went into the upper part of the tail.
The Chinese paddlefish had small, sharp, inward-curling teeth. As the fish grew, its teeth became smaller compared to its jaw. In adult fish, the teeth were fully joined to the bone. Unlike the American paddlefish, its upper jaw was not firmly attached to its skull. This allowed it to move its jaw to catch prey. Like other paddlefish, its skeleton was mostly cartilage. Its body had no scales, except for small ones near its tail.
Young paddlefish weighed about 1 to 1.5 kilograms (2 to 3 lb) by their first winter. By one year old, they were about 1 m (3 ft) long and weighed about 3.3 kg (7 lb 4 oz). After this, they grew much faster. They could weigh about 12.5 kg (28 lb) when they were around 1.5 m (5 ft) long. They became adults and could reproduce when they weighed about 25 kg (55 lb).
The maximum length of the Chinese paddlefish is often said to be 7 m (23 ft). One report from 1931 mentioned fishermen catching a Chinese paddlefish that was 7 metres (23 ft) long and weighed 907 kilograms (2,000 lb). However, scientists have not officially measured any over three metres (ten feet). Female fish likely grew larger than males once they became adults. Scientists estimated their lifespan to be 29–38 years.
Where Did the Chinese Paddlefish Live?
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The Chinese paddlefish lived in the Yangtze (Chang Jiang) River basin. This includes its estuary (where the river meets the sea) in the East China Sea. In the past, it was also found in the Yellow River basin and its estuary in the Yellow Sea. The Yellow River is connected to the Yangtze by the Grand Canal.
These fish mainly lived in large rivers. But sometimes they would go into big lakes. Because they were anadromous, adult fish were found in the coastal waters of the East China Sea and Yellow Sea. Sometimes, high tides would bring them into the lower parts of other rivers.
The species spent part of its life in the lower Yangtze River. This included the brackish water of its estuary (a mix of fresh and salt water). But they would migrate upriver and into major smaller rivers to gather for spawning. This happened in spring, from mid-March to early April. One spawning area was on the Jinsha River. It was about 500 m (1,600 ft) long and up to 10 m (33 ft) deep. The water flowed fast there.
A study showed that all spawning Chinese paddlefish were at least 8 years old. Females probably became adults later than males. They also likely did not lay eggs every year. They might have spawned every other year, or less often. Female fish could carry over 100,000 eggs. Each egg was about 2.7 mm (0.11 in) across. Young fish stayed in the upper parts of the Yangtze basin. Older fish were found throughout the Yangtze River.
How Did the Chinese Paddlefish Live?
The Chinese paddlefish usually lived alone. It swam in the middle and lower parts of the water. These fish were known to be strong swimmers.
Unlike its relative, the American paddlefish, which eats tiny organisms by filtering water, the Chinese paddlefish was a piscivore. This means it mainly ate other fish. It would eat small to medium-sized fish like anchovies, carp-like fish, and gobies. It also ate catfish and flounders. Sometimes, it would eat shrimp and crab too.
Its jaws could stick out, allowing it to grab prey. The upper jaw could thrust downwards and forwards to catch food. Like other paddlefish, the Chinese paddlefish had special sensors on its head and snout. These sensors, called ampullae, could detect weak electric fields. This helped them find prey in the water.
Why Did the Chinese Paddlefish Disappear?
The last records of Chinese paddlefish in the Yellow River basin are from the 1960s. However, their numbers started dropping much earlier, between the 13th and 19th centuries. Even though their numbers were falling in the Yangtze basin, people still caught about 25 tons each year in the 1970s.
In 1983, the Chinese government made it illegal to fish for the species. This was because their numbers were so low. A few fish were still found in the 1980s. For example, 32 were caught in 1985. Young fish were seen as recently as 1995.
By the time people realized how much danger the fish was in, it was very rare. Adult fish were also hard to keep alive in captivity. Because of this, efforts to start a breeding program in zoos failed.
Since 2000, there have been only two confirmed sightings of the fish alive. Both were in the Yangtze basin. The first was a 3.3-metre (10 ft 10 in), 117-kilogram (258 lb) female caught in Nanjing in 2002. The second was a 3.52-metre (11 ft 7 in), 160 kg (350 lb) female. This one was accidentally caught in Yibin, Sichuan, on January 24, 2003. The first fish died even though people tried to save it. The second fish was tagged with a radio tracker and released. But the tag stopped working after only 12 hours.
From 2006 to 2008, a research team searched the Yangtze basin. They used special sound equipment but could not find any paddlefish. A big study published in 2019 confirmed the species was extinct. This was based on not finding any paddlefish in surveys between 2017 and 2018. The study estimated the species went extinct between 2005 and 2010. But it was functionally extinct by 1993.
The main reasons for its extinction were too much fishing and the building of dams. The paddlefish was heavily overfished at all stages of its life. Young fish were easily caught. This, combined with the fish taking a long time to grow up, made it hard for their numbers to recover.
The building of dams, especially the Gezhouba Dam (which started working in 1981) and the Three Gorges Dam, trapped and separated fish groups. These dams also stopped the fish from swimming upriver to lay their eggs. Because of these findings, scientists recommended that the IUCN officially declare the species "Extinct." The IUCN did so in July 2022.
See also
- Baiji, a type of river dolphin that also lived in the Yangtze. It became extinct around the same time and for similar reasons.
- List of endangered and protected species of China
