The world’s largest recorded freshwater fish has been discovered in the Mekong River in Cambodia, say scientists.
The giant stingray measured almost 4 metres from snout to tail and weighed slightly under 300 kg, according to a statement on Monday by Wonders of the Mekong, a joint Cambodian-US research project.
The previous record for a freshwater fish was a 293 kg Mekong giant catfish, discovered in Thailand in 2005, the group said.
Freshwater fish are defined as those that spend their entire lives in freshwater, as opposed to giant marine species such as bluefin tuna and marlin, or fish that migrate between fresh and saltwater like the huge beluga sturgeon.
A team of scientists were called to examine the fish before it was released back into the river.
Are big fish endangered?
The stingray's catch was not just about setting a new record, Wonders of the Mekong leader Zeb Hogan said in an online interview with the University of Nevada.
“The fact that the fish can still get this big is a hopeful sign for the Mekong River,” he said, noting that the waterway faces many environmental challenges.
The Mekong River runs through China, Myanmar, Laos, Thailand, Cambodia and Vietnam. It is home to several species of giant freshwater fish but environmental pressures are rising.
In particular, scientists fear a major programme of dam building in recent years may be seriously disrupting spawning grounds.
“Big fish globally are endangered. They’re high-value species. They take a long time to mature. So if they’re fished before they mature, they don’t have a chance to reproduce,” Hogan said.
“A lot of these big fish are migratory, so they need large areas to survive. They’re impacted by things like habitat fragmentation from dams, obviously impacted by overfishing. So about 70 per cent of giant freshwater fish globally are threatened with extinction, and all of the Mekong species.”
What is known about giant stingrays?
The team that rushed to the site inserted a tagging device near the tail of the mighty fish before releasing it.
The device will now send tracking information for the next year, providing unprecedented data on giant stingray behaviour in Cambodia.
“The giant stingray is a very poorly understood fish. Its name, even its scientific name, has changed several times in the last 20 years,” Hogan said.
“It’s found throughout Southeast Asia, but we have almost no information about it. We don’t know about its life history. We don’t know about its ecology, about its migration patterns.”
Researchers say it’s the fourth giant stingray reported in the same area in the past two months, all of them females. They think this may be a spawning hotspot for the species.
Local residents nicknamed the stingray "Boramy,” or “full moon,” because of its round shape and because the moon was on the horizon when it was freed on 14 June.
In addition to the honour of having caught the record-breaker, the fisherman who discovered the stingray was awarded $600 (€569) for his troubles.