The Chinese paddlefish — one of the world’s largest freshwater fish — has officially been declared extinct after surviving some 150 million years.

The giant species, which measured as long as 23 feet and weighed as much as 1,100 pounds, has been killed off by overfishing and dam construction, according to research published in the Science of the Total Environment’s March issue.

“It’s very sad,” Zeb Hogan, a fish biologist at the University of Nevada, Reno, told National Geographic. “It’s the definitive loss of a very unique and extraordinary animal, with no hope of recovery.”

In the 1970s, 25 tons of paddlefish, which sported a long, spear-like nose and populated the Yangtze River and sometimes the East China Sea, were being harvested annually, according to Science of the Total Environment. But the construction of the Gezhouba Dam sped up their demise. The structure blocked access to upstream, where paddlefish would spawn, and downstream, where feeding grounds were. Research concluded that paddlefish became functionally extinct by 1993, meaning they were no long reproducing, and likely became extinct sometime between 2005 and 2010. The last paddlefish was seen in 2003 when researchers attached a tracking tag to one that was accidentally captured near Yibin in south-central China, Nat Geo said. The signal, however, was lost after the fish’s release. The Chinese paddlefish’s only remaining relative is the American paddlefish, found in the Mississippi River. Both are related to the sturgeon family, which is also threatened by extinction. Researchers said 140 other types of fish historically reported in the Yangtze River were not found, meaning most of them are endangered. Hogan warned that the extinction of the paddlefish could spell trouble for species of its kind.