A fisherman on the Mekong river in Cambodia last week hooked the biggest freshwater fish ever recorded, scientists said — a 300-kilogram stingray.
The giant stingray that measured about 13 feet in length was caught by a fisherman, Moul Thun, 42, with a hook and line near a remote island on the Mekong River in the Stung Treng area.
A fisherman on the Mekong river in Cambodia has hooked the biggest freshwater fish ever recorded, scientists say.
— AFP News Agency (@AFP) June 22, 2022
The fisherman contacted researchers the next morning and a team of scientists from the Wonders of Mekong research project helped tag, measure, and weigh the giant stingray before it was released back into the river.
Researchers maintained that it was healthy when released and expect it to survive.
The tag on the fish emits an audio signal which will enable researchers to track its movements to learn more about the behavior of the particular species.
By the time the researchers were contacted, they were already in northern Cambodia to install underwater receivers as part of the Wonders of Mekong project to track migratory river fish.
The Stung Treng area of the Mekong River consists of a healthy stretch with lots of deep pools up to 90 meters deep.
Zeb Hogan, a fish biologist at the University of Nevada, said, “we started focusing on this area as a stretch of river that’s particularly important for biodiversity and fisheries, and as the last refuge for these big species.”
Relatively little is known about the giant stingray
The Wonders of the Mekong research project group has been in contact with local fishermen for several months. Fishermen have been asked to get in touch if they land a significant catch.
On hooking this giant fish, Zeb Hogan, said, “the catch highlights how little we know about a lot of these giant freshwater fish…you have a fish that now holds the record for the world’s largest freshwater fish, and we know little about it.”
Hogan also stressed that “little is known about the giant freshwater stingray. The creature has a mouth about ‘the size of a banana’ with no teeth but with ‘gripping pads’ used to crush prey.”
“They’re on the bottom finding shrimps, mollusks, and small fish [which] can [be] suck[ed]…up with this banana-shaped mouth [to] crush them,” Hogan said.
Fishermen have reported three catches of female stingrays in the area during the past two months, Hogan said.
Scientists suspect the site could be an important seasonal gathering site for giant freshwater stingrays and might serve as a whelping ground for the young.
Researchers plan to tag and track a few hundred large fish in the Mekong River to better understand fish migrations and local habitat in the upper Cambodian Mekong area.
“This is the record for the largest fish that has spent its entire life in freshwater,” Hogan said of the recently caught ray.
The group has helped with two other large giant freshwater stingray releases in recent months. The fisherman who caught the record ray was paid market price for his catch.
Hogan said the prices are reasonable because the fish is not a fish that is highly prized for consumption.
The need to protect freshwater fish habitats
Worldwide, “most of these species of big fish are in trouble, [and] their populations are declining. The Chinese paddlefish was declared extinct in 2020,” Hogan said. “We need to do more to protect these freshwater habitats.”
“There’s potential for hydropower development right where these stingrays inhabit,” Hogan said, and “We want to understand the importance of this area before there’s any development, potentially in an unsustainable way.”
The upper Mekong area is also a habitat for Mekong giant catfish and other species of large freshwater fish.
The Cambodian government has expressed interest in developing a conservation plan for the giant freshwater stingrays.
The former world record-holding fish was a 646-pound Mekong giant catfish which was also caught in the Mekong River in 2005 in Thailand.
There are, additionally, other, larger recorded catches of fish that spend time in both fresh and saltwater, such as the beluga sturgeon.