Biologist Zeb Hogan has been looking for the world’s largest freshwater fish for 17 years. On June 13, his team found him. It’s a giant freshwater stingray, or Urogymnus polylepis.
Taken from the murky waters of Cambodia’s Mekong River, the stingray measured 3.96 meters before being returned to the river. And, at 300 kilograms, it weighed nearly seven kilograms more than a giant Mekong catfish caught in Thailand in 2005. Hogan said he had previously determined that the freshwater fish was the largest ever caught.
This species of giant stingray has an extremely dangerous venomous barb that can reach almost 30 cm in length, but it does not usually pose a threat to humans. More often, it ends up on the market as a source of cheap protein.
Fishermen in Cambodia alerted Hogan and his team from the Wonders of the Mekong project, which works to protect the river’s aquatic diversity in Southeast Asia and is sponsored by USAID (United States Agency for International Development), that they had caught a stingray larger than that anyone has ever seen. Team members hurriedly moved to an islet in the river called Koh Preah and lined up three industrial scales. Using a tarp, they hoisted the stingray out of the water and placed it on the scales to weigh it.
The discovery came less than a month after another giant stingray, this one weighing 181 kilograms, was caught and released nearby. Two other huge rays were caught this year.
“The fact that the world’s largest freshwater fish is caught in the Mekong River is astonishing,” commented Hogan. “This is a densely populated region. The river faces numerous problems, including intensive fishing.”
“This is the first fish we’ve tagged with an identifier tag,” said Hogan, who is also a research associate professor at the University of Nevada at Reno. In the coming months they plan to implant tags in hundreds of other fish.
With so many giant stingrays captured in recent months, all of them female, Hogan thinks this stretch of river and the deep pools it contains are crucial breeding ground for the species. The region is also home to porpoises, giant soft-shelled turtles, giant catfish and giant Siamese carp.
“So it’s a very unique and understudied site,” Hogan said. North American and European watersheds receive much more scientific attention.
While breaking the world record is of no scientific importance, Hogan said the giant stingray’s existence is an indicator of the health of its ecosystem. He also hopes the discovery will make the local population aware of how special this river is and how important it is to save it.
Populations of large freshwater fish are generally in decline due to a number of factors, including dam construction, intensive fishing and climate change. And many species of large fish are in danger of disappearing forever.
“In 2020 one of the candidates to be considered the largest freshwater fish in the world, the Chinese paddlefish, was declared extinct,” said Hogan. “It was very sad news and it made me fear that we were going to see more extinctions of these large fish, and not see records being broken.”
Fortunately, giant stingrays aren’t the only giant fish that have been in the news recently. In 2021, a lake sturgeon weighing a record 109 kilograms was captured and released into the Detroit River. And in May, a nearly 300-pound alligator fish may have broken the Texas state record for this freshwater fish, though the fisherman chose to release the animal rather than kill it and bring it in to be harvested. heavy.
“When you’ve had stories about fish breaking records, it’s a good sign,” said Hogan.
Translation by Clara Allain
