Giant Fish Thought to Be Extinct Has Been Rediscovered

A huge fish in the Mekong River once thought to be extinct has been spotted three times in recent years. "The giant salmon carp is like a symbol of the Mekong region," says Chheana Chhut, a researcher at the Inland Fisheries Research and Development Institute in Phnom Penh, Cambodia. The predatory fish can grow up to 4 feet in length, and has a conspicuous knob at the tip of its lower jaw. A striking patch of yellow surrounds its large eyes. With only three sightings between 2000 and 2005 and none for 15 years after the 2005 sightings, it was suspected to be extinct, researchers wrote in a study published in the journal Biological Conservation.

Since 2017, biologists tracking migratory fish species in Cambodia have developed relationships with local fishing communities, asking them to alert any unusual sightings. That's how the three giant salmon carp found in the Mekong River and a tributary in Cambodia between 2020 and 2023 came to the attention of researchers, the AP reports.

• "I was really surprised and excited to see the real fish for the first time," says Bunyeth Chan, a study co-author and researcher at Svay Rieng University in Cambodia. Researchers say the sightings give them new hope for the fate of the species. One nickname for the species is "ghost fish."

• "This rediscovery is very exciting, positive news," says Zeb Hogan, a fish biologist at the University of Nevada, Reno, who was part of the team.
• But the plight of the fish also spotlights the perils facing all migratory species in the Mekong, which faces industrial pollution and overfishing. More than 700 dams are built along the river and its tributaries and there are very few functional "fish passages" to help species navigate obstructions, says Brian Eyler, director of the Southeast Asia Program at the Stimson Center in Washington.
• The giant salmon carp, however, has an "emblematic" status and its conservation "could have an umbrella effect contributing more broadly to the conservation of the globally significant freshwater biodiversity in the Mekong Basin ecosystem," researchers wrote.

(More Mekong stories.)