("Ocean Mysteries with Jeff Corwin"/Litton Entertainment)

The catch took about five hours, and the fishermen had to rotate in shifts to give respites from the back-breaking work. Using a classic rod-and-reel set-up and aboard a simple, long boat, the scientists and fishermen managed to capture the giant freshwater stingray in Thailand’s Mae Klong River last week.

Then, they measured it: At 14 feet long and 8 feet wide and weighing an estimated 600 to 800 pounds, the creature could be the largest freshwater fish ever captured and recorded. The current record is held by a 693 pound-catfish caught in Thailand in 2005.

The capture was caught on camera and will air on a future episode of ABC's "Ocean Mysteries with Jeff Corwin."

Corwin was standing on a 5-acre calcium formation in the middle of Thai waters, looking for bass, when The Post reached him by phone. The conservationist and television show host has been in the country for about a month, filming segments with the help of local fishermen and scientists.

"The science is what makes this epic to me," Corwin said. "It's a personal and professional check off my bucket-list."

Scientists know very little about giant freshwater stingrays, which are some of the oldest fish on the planet. This was especially important for Nantarika Chansue, a veterinarian in Bangkok and university professor, who took Corwin out on the expedition. After measuring the animal, she discovered that she had actually caught and tagged this very same fish in 2009.

"It's the very first step to try and unravel the mysteries of this animal's life cycle," said Zeb Hogan, who runs the Megafishes Project and is a professor at the University of Nevada, Reno. "Every little bit we can learn about this fish can potentially help protect it."

Hogan, a National Geographic fellow, had been a part of the 2009 expedition that caught the stingray. Researchers don't know much about the giant freshwater stingray, Hogan said, including how large they can grow and at what rate, how long they tend to live and its ecology. For instance, does it make its way to the ocean at some point in its life cycle?

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Scientists can learn a great deal by catching a previously tagged fish. DNA and blood samples help fill in clues about diet and pollution exposure, and measurements can tell us more about how quickly they grow.

Given that this particular fish was pregnant both times it was caught, Hogan believes where it was found is likely a nursery area.

TV host Jeff Corwin and veterinarian Nantarika Chansue examine a giant freshwater stringray caught in Thailand's Mae Klong River. The fish, which weighs an estimated 600 to 800 pounds, was later released. (Ocean Mysteries with Jeff Corwin/Litton Entertainment)

Giant freshwater stingrays live in southeast Asia. Considered an endangered species, the fish have had to endure water pollution, river damming cutting off access to other habitats, and over-fishing when they are smaller, Hogan said.

People live along the Mae Klong River where the stingray was caught; it's highly traveled, and parts of the river are urban. A market floats nearby.

"This is an amazing river system, a culturally important river system, but it's highly stressed," Corwin said. "We're sitting in the pen, examining this beautiful behemoth of a ray, and we're being constantly washed over by plastic."

The team actually caught a few other rays that day, but the fish got away or weren't nearly as large. Using snakehead fish as bait, a plastic jug as a bobber, line as thick as yarn and a special hook that disintegrates in a week, the fisherman hooked the stingray and tied the line. Then came the hard part.

Stingrays burrow under the mud on the river's bottom, and their flat, dinner-table like body functions like a suction cup. Corwin said the boat of eight people was essentially pulled up river by the fish.

"My passion is fishing, I love catching tuna," Corwin said. "I thought I had the chutzpah, and I tell you what, I was looking at my cameraman, and I said, '... I'm going to bloody puke in two seconds.' And then one of these Thai fisherman, he's all muscle, takes over, and he's tugging as much as I am."


("Ocean Mysteries with Jeff Corwin"/Litton Entertainment)

Once the fish let go from the bottom, the men scooped it up, cradled it and placed it in a underwater, mesh pen. They covered the fish's stinging spine.

After collecting samples and measurements, Corwin, Chansue and the team let the stingray go. They weren't able to weigh the fish without harming it, so we may never truly know if it beat the previous record-holder. The expedition was a collaboration with a sport fishing company, which lets people catch these kinds of fish for scientists to examine, and then release.

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In 2009, the stingray measured about 6.5 feet wide and 15 feet long. Six years later, it had grown to almost 8 feet wide, although it was about a foot shorter. Hogan said it's not unusual for stingrays to lose parts of their very long tail, which may have happened in this case.

About 30 species of freshwater fish can grow to be over 6 feet long and weigh more than 200 pounds, and they appear on six continents, Hogan said. "Some of them we know about, but many of them remain a mystery," he said.

By contrast, large, ocean-dwelling fish have been well-studied and documented. Freshwater fish, by contrast, are more localized creatures that don't necessarily draw in worldwide efforts and experts.

"Ocean fish, by their nature, are very global," Hogan said. "People work together all over the world to learn about ocean fish, but people don't work together in the same way to learn about freshwater fish."

The fortuitous catch in Thailand could help scientists figure out why these ancient creatures still swim in Earth's fresh waters, and how to make sure they still can in the future.


A different giant freshwater stingray that Hogan has caught. (Courtesy of Zeb Hogan, University of Nevada, Reno)