By Dr. Becker
When many people think of stingrays, they think of the ocean-dwelling varieties. There’s also a giant freshwater stingray that lives in the river systems in Southeast Asia and northern Australia, and is thought to be one of the oldest fish on the planet.
Giant stingrays can grow up to 16.5 feet long and weigh more than 1,300 pounds. Their appearance, gray or brown in color, wide and flat in the body with a long “ray” for a tail, has changed little in millions of years.1
Yet, despite its ancient history, giant stingrays have only been known to science for about two decades, and they’re shrouded in mystery. No one knows for sure where they prefer to live, how many are in the environment, or if they ever travel to the ocean.
Researchers in Thailand are one step closer to learning more about these majestic creatures as they captured a giant stingray that may very well be the largest freshwater fish ever recorded.
Giant Freshwater Stingray in Thailand May Be Largest Freshwater Fish Caught
Researchers in Thailand working with the Megafishes Project collaborate with a sport fishing company to catch giant stingrays, examine them, and then release them back into the wild. Even the hook used is designed to disintegrate within a week.
The capture, which took five hours and was caught on camera to air on ABC's "Ocean Mysteries with Jeff Corwin,” brought in a giant stingray that measured 14 feet long and 8 feet wide from Thailand’s Mae Klong River. It was estimated to weigh 600 to 800 pounds, but could not be weighed exactly as doing so may have hurt the animal.
For comparison, a 693-pound catfish, also caught in Thailand, currently holds the record for largest freshwater fish caught. After examining the stingray, the researchers realized it has been previously caught and tagged in 2009. Pregnant both times, it’s believed the area serves as a nursery for stingrays.
Since the last tagging, the ray had grown in width about 1.5 feet and lost about a foot in length; it’s common for stingrays to lose parts of their tail. The research efforts are geared toward learning more about these creatures, including ways to better protect them.
Giant freshwater stingrays are an endangered species. Primary threats include water pollution, over-fishing and river damming, which cuts off their access to habitat. National Geographic explained:2
“Stingray numbers appear to have dropped dramatically in recent years as their riverine habitats have degraded, and it appears they no longer inhabit some parts of their historical range.”
Jeff Corwin also told The Washington Post:3
"This is an amazing river system, a culturally important river system, but it's highly stressed… We're sitting in the pen, examining this beautiful behemoth of a ray, and we're being constantly washed over by plastic."
The Power of a Giant Stingray
During the stingray capture described above, the ray was able to pull the boat (with eight team members inside) up river. It was nearly the size of a car, after all, and able to burrow into the river’s muddy bottom like a strong suction cup. According to National Geographic:4
“Large stingrays have been known to pull boats upstream and even underwater.”
Although not typically aggressive toward humans, stingrays have a barb located at the base of the tail (not at the tip, as is commonly believed). A stingray barb can penetrate bone and also releases toxins into the wound, which can be fatal.
Sixty-nine species of rays are even “electric” with an ability to electrically shock and stun prey and predators using a specialized organ. Such rays can be deadly to humans; if a diver is stunned he may become unconscious and drown.5
Unbeknownst to many, stingrays belong to the elasmobranchs group, which are fish with skeletons made out of cartilage, not bone, and gill slits (five or more) on the side of their heads. What other fish does this describe? Sharks! Stingrays are actually closely related to sharks.
George Burgess, an ichthyologist at the Florida Museum of Natural History, in Gainesville, joked to National Geographic:6
"Imagine a shark body. Then imagine a steamroller going over the top of it. That's how you make a ray."