YANGTZE, CHINA — The Chinese paddlefish has been declared extinct.
But what was it and why has this happened?
The Chinese paddlefish was thought to be the world's largest freshwater fish with an average length of 10 feet.
Some reports recorded them reaching 23 feet and weighing half a ton.
The Chinese paddlefish had a long, silver-gray body and their name derived from their protruding snout that resembled a paddle.
The fish were prominent in many parts of the Yangtze, Asia's largest river flowing 3914 miles from the Tibetan Plateau to the East China Sea.
They used their special sword-like snout to sense electrical activity to find prey, such as crustaceans and fish, however, they haven't been spotted since 2003.
In the journal Science of The Total Environment, a team of researchers at the Chinese Academy of Fishery Sciences in Wuhan declared the paddlefish as extinct.
They believe overfishing in the 1970s, which harvested 25 tons of paddlefish per year on average was the root cause of the gradual decline in paddlefish.
However, the main contributor which led to extinction was the loss of habitat through the construction of the Gezhouba Dam, built on the main stem of the Yangtze.
The dam was constructed without a fish ladder or bypass, cutting off the paddlefish from their only spawning grounds upstream.
The team tried to locate the paddlefish at hundreds of locations along the Yangtze using nets, sonar and electro-fishing gear.
Researchers even monitored fish markets around the country but found nothing.
Based on the previous population size and the intervals between sightings, the researchers used a mathematical model to determine the likelihood that the species is, in fact, extinct and most likely went extinct between 2005 and 2010.
The researchers believe that this is a hard lesson in conservation.
Sadly, efforts to save the paddlefish did not begin until the fish had already gone.