For 17 years, Zeb Hogan, a biologist, has been searching for the world’s largest freshwater fish. On June 13, his team found it — a giant freshwater stingray or Urogymnus polylepis.
The ray, which was rescued from the murky waters of Cambodia’s Mekong River, was 10 feet (3 meters) long before returning to the river. And at 661 pounds, it was 15 pounds heavier than a giant Mekong catfish caught in Thailand in 2005. dr. Hogan said he previously determined that freshwater fish was the largest ever caught.
Although this species of giant stingray has an extremely dangerous venomous barb that can grow to nearly 12 inches (30 cm) in length, they usually pose no threat to humans. More often they come on the market as a cheap protein source.
Fishermen in Cambodia warned Dr. Hogan and his team at Wonders of the Mekong Project, which works to protect the aquatic diversity of the Southeast Asian River and is sponsored by the United States Agency for International Development, captured a stingray larger than ever before . seen. Team members rushed to the small river island called Koh Preah and lined up three industrial scales. Using a sail, the stingray was lifted out of the water and lifted onto the scales to check its weight.
The discovery comes less than a month after another giant stingray — which weighs 400 pounds — was captured and released nearby. Two other huge rays were also caught this year.
“The fact that the world’s largest freshwater fish has been caught in the Mekong is remarkable,” said Dr. hogan. “This is a densely populated region and the river faces a lot of challenges, including a lot of fishing.”
In another first, Dr. Hogan was able to acoustically tag the stingray to track the animal for up to a year with an array of 36 underwater receivers also recently installed in part of the river.
“This is the first fish we’ve noticed since deploying the array,” said Dr. Hogan, also an associate professor of research at the University of Nevada, Reno. Over the next few months, they plan to tag hundreds of additional fish.
With so many giant stingrays caught in recent months and all of them female, Dr. Hogan that this part of the river and the deep pools it contains are a critical breeding ground for the species. The area is also home to freshwater dolphins, giant softshell turtles, giant catfish, and giant barbs, which belong to the carp family.
“So it’s a very unique place, and very underexposed,” he said. North American and European river systems are receiving much more scientific attention.
While breaking the world record was not scientifically important, said Dr. Hogan that the existence of this fish is an indicator of the health of its ecosystem. He also hoped the discovery would remind the local community how special this river is and how much it needs to be saved.
Due to a combination of factors, including dam construction, overfishing and climate change, large freshwater fish populations are generally declining. And many species of large fish are in danger of disappearing forever.
“In 2020, one of the contenders for the world’s largest freshwater fish, known as the Chinese paddlefish, was declared extinct,” said Dr. hogan. “That was very sad news, and I had a feeling that we would see more extinctions of these big fish than records being broken.”
Fortunately, the giant stingrays aren’t the only tales of giant fish of late. In 2021, a record-breaking 240-pound sturgeon was caught and released into the Detroit River. And in May, a nearly 300-pound alligator shrimp may have broken the Texas state’s record for freshwater fish, though the fisherman chose to release the animal rather than kill it and bring it in to be weighed.
“When you hear stories about record fishing, that’s a good sign,” said Dr. hogan.