Giant stingray could be worlds biggest

As part of an exhibition to explore the freshwater fish of southeast Asia - scientists caught what could be the world’s biggest stingray.

The stingray caught by the Megafishes Project team, which is conducting an expedition to tag freshwater fishes in southeast Asia

The fish was tagged and released in central Thailand during the National Geographic expedition, which seeks to find and protect specimens of the world's largest freshwater fish.

Conservation biologist and the lead researcher on the expedition, Zeb Hogan of the University of Nevada Hogan said: "In terms of disk width, this is the second largest stingray I’ve seen, the largest was in Cambodia in 2003. This recent fish was very thick, so it may have weighed more."

"It's clear that this species of giant freshwater stingray has the potential to be the largest freshwater fish in the world," Hogan said. The current record holder for world’s largest freshwater fish is a 646lb Mekong giant catfish caught by fishermen in northern Thailand in 2005.

Hogan, along with his team of researchers and anglers on site at the time of capture, approximate the fish’s weight to be between 550 and 770lbs. An even slightly larger fish than the one tagged would almost certainly be a world record freshwater fish, said Hogan.

Freshwater giant stingrays are among the largest of the approximately 200 species of rays. They can be found in a handful of rivers in Southeast Asia and northern Australia.

After the first catch, the researchers encountered the stingray again, 4 km away from where they initially caught it. "Surprisingly, we caught the stingray again four weeks later," Hogan said. The find could mean that the ray population is smaller, or less migratory, than originally believed.

Biologists continue to track the big fish’s movements using an array of underwater listening devices designed to detect tagged fish. Hogan and his team have tagged 18 of this species of stingrays (Himantura chaophraya) as part of the recently established research project on the stingray in central Thailand for the University of Nevada, Reno, the Thai Department of Fisheries, the sport-fishing company Fishsiam and the National Geographic Society sponsored Megafishes Project.