Chinese Paddlefish: How We Killed It

By Geoffrey Migiro on February 14 2020 in Environment

Gladius the Chinese paddlefish swims with open mouth.
Gladius the Chinese paddlefish swims with open mouth.
  • The Chinese paddlefish was one of the largest freshwater fishes on the planet.
  • The last living Chinese paddlefish was sighted in 2003
  • The hydroelectric dams constructed along the Yangzi River contributed to the extinction of the Chinese paddlefish

The Chinese paddlefish, also referred to as the Chinese-swordfish, was one of the world’s largest fishes that was declared extinct by Chinese fisheries experts in 2019. The Chinese paddlefish is an ancient fish that is believed to have thrived since the Lower-Jurassic era about 2million years ago. The Chinese paddlefishes were native to the Yellow and Yangzi River basins. It was an anadromous fish that spent a considerable percentage of its life in the sea and only went upriver to spawn during spring. It was the last member of the genus Psephurus and 1 of the 2 extant fish species belonging to the paddlefish family until 2019 when a report by the River-Yangtze-Fisheries-Research Institute suggested that it disappeared between 2005 and 2010. The IUCN has listed the Chinese swordfish as critically endangered since the 1990s. The Chinese paddlefishes have been functionally-extinct since 1993. The last living member of the paddlefish family is the American paddlefish. 

Description

The Chinese paddlefish had a maximum length of about 23 ft, and it weighed over 1,100 pounds. The head and back of this fish were grey while its underbelly was white, and its extremities (fins and rostrum) are pinkish. The Chinese paddlefish’s sides have a white ridge that stretches from the center of its body to its caudal fin. Its titular paddle is not flattened; it is wedge-shaped with a triangular profile while the titular paddle of the American paddlefish has a flattened rectangular profile. The Chinese paddlefish had small round eyes and small teeth. Its pointed and narrow paddle reached 33.3% of its body length. The body of this paddlefishes is quite smooth and mostly lacks scales except for the small ones found on its caudal fin and caudal peduncle. They attain sexual maturity by the time they are about 7 or 8 years old with a body length of about 6 ft and weighing about 55 pounds. Limited studies have been done on the Chinese paddlefish’s weight and size since it is critically endangered and lack of sighting in several years. Although the most acceptable maximum size if 10 ft in length and 660 pounds in weight. 

Distribution

The Chinese swordfish was indigenous to River Yangtze and its branch at the East-China Sea. However, it was also discovered in the Yellow River, which is connected to River Yangzi by the Grand-Canal, and its branch at the Yellow Sea. It spent a considerable percentage of its life in the lower parts of River Yangzi, including the brackish waters of its branch. During spring (mid-March to Late April), it migrated into the River Yangzi’s main branches to spawn. These paddlefishes inhabited huge rivers, but sometimes they migrated to huge lakes. Adult Chinese paddlefishes were found on the coastal waters of the Yellow and East-China Seas, and occasionally, the spring tide brought some of them into the lower parts of Yangjian and Qiantang rivers. Chinese paddlefishes were solitary creatures that lived in the lower-mid layer of the water-column. Unlike their American counterparts which feed of plankton foods, the Chinese paddlefishes consume small fishes like gobiids, cyprinids, anchovies, and bagrids; as well as crabs, shrimps, bothids, and bagrids. Scientists believe that these paddlefish locate its prey using the electroreceptors on its rostrum, just like the American paddlefish. However, the study conducted on this issue is due to be ratified.

Conservation Status Of The Chinese Paddlefish

The Chinese Swordfishes have been listed as first-level protected fish of China since 1983. The last living paddlefish was seen in 2003, although there is a report of a dead one that was sighted in 2007. The Chinese paddlefishes were reported extinct in 2019 by Qiwei Wei, the co-author of the Science-of-the-total-environment journal that was published in the same year. The IUCN will change the official status of the Chinese paddlefish in June 2020. Even though a population decline was noted from the thirteenth to the nineteenth centuries, the paddlefish was last sighted in the Yellow-River and its branches in the 1960s. The population decline was quite significant in its primary habitat in the Yangzi River, but the annual fishing of over 25 tons continued in the 1970s. The paddlefishes were still being caught in the river during the 1980s, although in small numbers (only 32 paddlefishes were caught in 1985). The young Chinese paddlefishes were allegedly sighted in 1995.   

There have been only 2 reported sightings of Chinese paddlefishes at the Yangtze basin since 2000. The first one was the 11 ft long female paddlefish weighing about 258 pounds that was caught in 2002. The second one was an 11.5 ft female paddlefish weighing about 353 pounds, which was captured on January 24, 2003, at Yibin, Sichuan by Liu Longhua. The first one died despite several attempts to save its life while the second one was radio-tagged and released into the sea. The tag stopped working 12 hours after it was released into the wild.

A research team from Chinese-Academy-of-Fisheries science searched for a paddlefish at the Yangzi basin from 2006 to 2008 but didn’t catch any fish. However, they recorded 2 probable specimens underwater using hydroacoustic signals. Even though there might be a small number of paddlefish in the seas, most researchers consider it to be extinct. A 2009 research confirmed that the paddlefish might be extinct after an extensive survey of Yangzi from 2017 to 2018 that didn’t report any live findings.     

How Did We Kill Them?

The Chinese and the American paddlefishes have survived for over 2 million years. They have lived through various unimaginable changes like the extinction of the plesiosaurs, which swam with it in the sea and the development of various cities and towns along the shores of its habitats. The only thing they couldn’t survive was the human being. No young Chinese paddlefish have been sighted in the region since 1995, and no adult has been spotted in the wild since 2003, resulting in many people fearing that they are extinct. Even if scientists find evidence of their existence in the future, they fear that the population is already too low to be able to reproduce successfully. Some of the factors that led to their extinction include:

Construction Of Dams

One of the main factors that contributed to their extinction was the construction of the Three-Gorges Dam and the Gezhouba Dam. Gezhouba Dam is situated in Yichang City in Hubei Province. The Gezhouba Dam is located a few miles from downtown-Yichang, just downstream of Huangbo River’s fall into the Yangzi River. Gezhouba Dam has a capacity of about 2,715 MW. The construction process, which began on December 30, 1970, ended in 1988. The dam was constructed at the place where 2 islands (Xiba and Gezhouba) split River Yangzi into 3 channels. Gezhouba Dam has a maximum height of about 154 ft, and it is 8,514 ft long. Gezhouba Dam was the first dam to be constructed in the region that affected the population of the Chinese paddlefishes. The dam was erected without a bypass or a fish ladder. Therefore, it blocked the fish from its only spawning region, which had been discovered by the late-1970s. The population of these paddlefishes continued dwindling after the dam was erected, but nobody knew that their population was reducing at a very fast rate.

Another dam that affected the Chinese paddlefish’s habitat is the 3 Gorges Dam, which has been the largest hydroelectric power station on the planet in terms of capacity since 2012. The dam managed to produce over 101.6 terawatt-hours in 2018. The 3 Gorge dam is 7,661 ft long, and its 607 ft above the sea level. The construction of the dam’s body was finished in 2006; however, the entire project was fully functional by 2012. The Chinese government considers the 3 Gorge dams to be a monumental project that will affect its citizens both economically and socially. However, the project has displaced over 1.3 million Chinese and flooded several cultural and archaeological sites.

These dams increased energy production in China and also lowered the potential for flooding downstream, which could have affected many people. However, they ended up polluting the paddlefish’s habitat and contributing to their extinction. The dams blocked their anadromous spawning migration life cycle of the Chinese paddlefishes resulting in a population decrease. The dams also caused population fragmentation, which affected their reproduction cycle, thus making it impossible for their population to grow.

Overfishing

The giant Chinese paddlefishes were once common in the Yangtze River. Their enormous size made them quite famous with the local fishermen who caught them for food. The Chinese paddlefish meat was quite popular with the ancient Chinese emperors. The young ones were easily caught using numerous traditional fishing methods; therefore, reducing their abilitys to sustain a viable population. Even though the paddlefishes have been harvested for centuries, they were not declared Critically Endangered until the hydroelectric dams were constructed on River Yangtze. The dams blocked their spawning migratory cycle was not affected, which made it impossible for the Chinese paddlefishes to reproduce and maintain their population. Therefore, the annual fishing of about 75 tons of Chinese paddlefishes accelerated the decline in population. With their number not increasing, it was easy for them to be wiped out through overfishing.   

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