The capture of this amazing fish was caught on camera and it’s going to air on a future episode of ABC’s “Ocean Mysteries with Jeff Corwin,” The Washington Post reports.
Then it was time to measure this huge freshwater stingray, and it didn’t disappoint. At eight feet across and 14 feet long, it’s estimated that this huge stingray may weigh between 600-800 pounds. Right now, the current record for the largest freshwater fish captured and recorded was another fish also caught in Thailand — a 693 pound catfish.
There is an air of mystery surrounding these huge fresh water stingrays, and very little is known about them. They are some of the oldest fish on the planet. All stingrays are in the class Chondrichthyes, and this includes all 850 species of sharks, rays, skates, and chimaeras, according to RayLady. While other members of this class have been swimming the oceans since the Paleozoic era, it’s thought that the flattened body plan of the stingray evolved during the Jurassic period, around 100 million years ago. Unlike other fish, stingrays lack a swim bladder and have powerful jaws evolved to make short work of molluscs like clams and mussels, and this is one reason why they are so successful today.
After measuring the huge stingray, Corwin’s friend Nantarika Chansue, a veterinarian in Bangkok as well as a university professor realized she’d also caught and tagged this very same creature in 2009.
“It’s the very first step to try and unravel the mysteries of this animal’s life cycle,” Zeb Hogan, who runs the Megafishes Project and is a professor at the University of Nevada, Reno, told The Washington Post. “every little bit we can learn about this fish can potentially help protect it.”
Hogan is a National Geographic fellow and also part of the 2009 expedition that caught the stingray. There’s lots of questions researchers have about this fish. How large can it grow, and how fast? How long does it live and does it make its way to the ocean at some point?
Capturing a previously tagged fish can help scientists to learn a good deal–DNA and blood samples can provide clues about the creature’s diet and exposure to pollution. Measurements can inform scientists about how quickly they grow.
Most interestingly, this particular fish was pregnant each time it was caught. This leads Hogan to believe the place where it was found is likely a nursery area, The Washington Post reports.
Giant freshwater stingrays are native to southeast Asia, and they are considered an endangered species. They have to deal with water pollution, river damming, which cuts off their access to other habitats, and they are also often over-fished when they are smaller, Hogan said.
The Mae Klong River is a populated here and there with homes and a local market and it’s highly traveled.
“This is an amazing river system, a culturally important river system, but it’s highly stressed,” Corwin told The Washington Post. “We’re sitting in the pen, examining this beautiful behemoth of a ray, and we’re being constantly washed over by plastic.”
To capture the stingray, the team used a snakehead fish as bait, line as thick as yarn, a plastic jug as a bobber, and a special hook that dissolves in a week. Then the fishermen hooked the critter.
That was the easy part.
Stingrays can use their flat bodies to act like suction cups when they burrow in the mud and Corwin said this stingray towed the boat full of eight people up the river.
“My passion is fishing, I love catching tuna,” Corwin told The Washington Post. “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.”
When the fish finally let go of the bottom, the men cradled it carefully and placed it in an underwater pen. They also covered up the stinging spine.
Once samples and measurements were collected, Corwin, Chansue and their team let the stingray go. It wasn’t possible to weigh the fish without causing harm, so it isn’t known if it would beat the previous record-holder. Interestingly, the expedition was part of a collaboration with a sport fishing company that lets people catch fish for scientists to examine and then release.
The giant freshwater stingray is thought to be mature at around 110 cm across and it gives birth to live young that are generally 30 cm across. While it is venomous, it only uses that scary-looking sting in self-defense as it snuffles along the bottom searching for invertebrates and small fish, Arkive reports.
This huge, flying carpet of a fish occurs in most large rivers in tropical Australia, as well as the Fly River basin, New Guinea, the Mahakam River basin, Borneo and in several rivers in Thailand.
Thai fishermen reported catching 25 of these fish in 1992, but the following year the figure plummeted to just three, obviously hinting to a rapid decline. The biggest threats to this magnificent fish are poor habitat management, and this even includes the destruction of the forest canopy and that leads to drought upstream and flooding downstream during monsoons. Dam building is another key threat which prevents migratory fish from breeding successfully and reduces available prey.
In Australia it’s thought that silt from uranium mines, which contains heavy metals and radio-isotopes, is the biggest threat to this species, although exactly how threatening is unknown. The stingray is also under threat from direct and incidental fishing, habitat loss, and range fragmentation which leads to inbreeding depression, Arkive notes.
There needs to be more research into this fish’s biology and its status, Arkive reports. The Australian government hopes to form a national recovery team, which will attempt to compile information on the distribution, abundance, and ecology of the giant freshwater stingray.
By taking these steps, perhaps scientists will be able to save this remarkable animal so that it may continue for many more generations to come.
