A Massive, Mysterious ‘Ghost’ Fish, Feared Extinct for Nearly 20 Years, Has Been Rediscovered in Cambodia

In 2020, scientists were thrilled to hear rumors that fishermen in Cambodia had caught a giant salmon carp—a large, salmon-shaped fish with a hooked jaw and a yellow patch around its eyes. No one had documented this rare species since 2005, and experts feared it had gone extinct.

Unfortunately, the fish at the heart of the rumor was sold before scientists could get their hands on it. Three years later, however, Cambodian fishermen flagged two other unexpected catches made in the Mekong River, and researchers immediately purchased the large fish to examine them.

“Even though the fishermen … hadn’t seen the fish before, they knew that they had something remarkable, unusual,” Zeb Hogan, a biologist at the University of Nevada, Reno, and co-author of the study, tells CNN’s Jessie Yeung. “They knew that it was worth contacting us.”

This time, upon examining the fish, the scientists got to celebrate: They were indeed two specimens of the giant salmon carp, nicknamed the “Mekong ghost” because of its rarity—the fish had been elusive even before it was feared extinct. The positive identification also makes it more likely that the rumors from 2020 were true. The findings were recently published online in the journal Biological Conservation.

“I was really surprised and excited to see the real fish for the first time,” Bunyeth Chan, a researcher at Svay Rieng University in Cambodia and lead author of the study, tells the Associated Press’ Christina Larson.

The three recent identifications were made outside of the species’ expected geographic range, suggesting the fish’s distribution might be more extensive than previously believed, per Nevada Today’s Michelle Werdann.

Though the documentation of this mega fish—which can measure up to four feet long and weigh up to 66 pounds—is happy news, the giant salmon carp remains critically endangered. Since the species was formally identified in 1991, fewer than 30 specimens have been recognized.

“The rediscovery of the giant salmon carp is a reason for hope, not just for this species but for the entire Mekong ecosystem,” Chan tells Nevada Today. “The Mekong ecosystem is the most productive river on Earth, producing over two million tons of fish per year worth over $10 billion.”

The Mekong River is also the longest river in Southeast Asia—flowing through China, Myanmar, Laos, Thailand, Cambodia and Vietnam—and it’s home to more than 1,100 species of fish. Nearly one-fifth of those, however, are at risk of extinction, according to a report published this year by the World Wildlife Fund and partners. The Mekong ecosystem is threatened by human activity, including overfishing, climate change, sand mining and the construction of hydropower dams that severely impede migratory species and could impact the giant salmon carp.

More than 700 dams have been built throughout the Mekong River and its tributaries, Brian Eyler, director of the Southeast Asia Program at the Stimson Center who was not involved in the study, tells the Associated Press. The dams leave little room for the fish to migrate and have also been endangering traditional river livelihoods, Lilith Foster-Collins reports for Newsweek.

“This discovery is a call to action to protect the Mekong River and its amazing fisheries and biodiversity,” Hogan tells Nevada Today. “The survival of the giant salmon carp depends on the ability of governments, scientists and communities in the Mekong region to ramp up conservation efforts and work together.”

In the meantime, his team hopes to continue working with fishing communities along the river to gather more details about the mysterious giant salmon carp.

“Local fishers possess invaluable ecological knowledge and could be pivotal in identifying key habitats and establishing conservation zones,” Sébastien Brosse, a co-author of the study and a biology and biodiversity researcher at Paul Sabatier University in France, tells Nevada Today.

Margherita Bassi | READ MORE

Margherita Bassi is a freelance journalist and trilingual storyteller. Her work has appeared in publications including BBC Travel, Discover magazine, Live Science, Atlas Obscura and Hidden Compass.