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The giant freshwater stingray is an elusive species that scientists don’t know much about. Moul Thun hooked into it by accident on June 13 2022, the largest freshwater fish ever caught.
As part of the Wonders of the Mekong research team, Dr. Zeb Hogan studies this and many other freshwater megafauna species that inhabit the mighty Mekong River.
The team had been in communication with local fishermen in case such an incident occurred and got on location to weigh the fish when Thun hooked into the monster stingray.
Weighing in at 661 pounds and measuring 13 feet, the massive ray has been known to reach lengths of 16.5 feet and even heavier weights of 1,300 pounds.
Several anglers attempting to reel one of these monsters in were taken by surprise, with some capsizing their vessels due to the big fish’s pull.
While usually not a threat to humans, they sport a venomous barb on the tail which can puncture skin and even bone, injecting a toxin into any wound it causes.
Fortunately for researchers, this particular specimen had broken off its barbed tail.
Dr. Hogan and his team have managed to capture two giant stingrays weighing over 400 pounds this year, in addition to the world record holder for largest freshwater fish ever caught from 2005 – a 646 pound catfish out of Thailand’s Mekong River.
By safely tagging and releasing these sizable creatures, the researchers hope to unlock crucial data and make progress on understanding a species and habitat that has long been an enigma.
For almost two decades, Dr. Hogan has been studying the world’s largest freshwater fish in the Mekong, where deep troughs hold some of the largest species on earth.
Dr. Hogan said the Chinese paddlefish, one of the world’s largest freshwater fish, was declared extinct in 2020.
That was very sad news, and I felt like we were going to see more extinctions of these big fish rather than records being broken.
The giant freshwater stingray is on the IUCN Red List of Threatened Species as endangered, but it is not illegal to fish for it in Cambodia.
However, they aren’t regarded as great table fare, so fishermen don’t often target them.
As bottom-dwelling creatures that consume shrimp, mollusks, and small fish, they are often caught by nets or hooks in deep waters.
“Catching the world’s largest freshwater fish in the Mekong is remarkable,” Dr. Hogan said. “This is a heavily populated region, and the river faces numerous challenges.”
The construction of megadams is one of the most significant challenges. T
he massive structures obstruct the flow of fish in the river, despite the presence of aids like fish ladders.
Additionally, the giant dams promise to uproot small villages, bottleneck food supplies in the area, and increase the dramatic effects of floods and droughts.
A 1,400-megawatt hydropower dam is being built on the Mekong north of Stung Treng. “It will mean the loss of fisheries, biodiversity, livelihoods,” Dr. Hogan said.
Thun caught this particularly impressive specimen in a deep area of the Mekong, where pools can reach up to 90 meters deep.
Due to overfishing, pollution, and dam construction, it is unknown if the river can sustain freshwater megafauna of this caliber for as long as it does.
Several big fish are migratory, so they need large areas of land to survive, Dr. Hogan noted. “Many of these big fish are endangered.
They are high-value species. They take a long time to mature. If they are fished before they mature, they cannot reproduce.”
Sources Themeateater
