Science

A Giant Stingray May Be the World’s Largest Freshwater Fish

For 17 years, Zeb Hogan, a biologist, has been trying to find the world’s largest freshwater fish. On June 13, his crew discovered it – an enormous freshwater stingray, or Urogymnus polylepis.

The ray, hauled out of the murky waters of the Mekong River in Cambodia, measured 13 ft in size earlier than it was returned to the river. And at 661 kilos, it was 15 kilos heavier than a Mekong large catfish caught in Thailand in 2005. Dr. Hogan mentioned he had beforehand established that freshwater fish as the largest ever caught.

While this species of large stingray has an especially harmful venomous barb that may attain practically a foot in size, they don’t seem to be often a risk to people. More typically, they wind up in the market as a supply of low-cost protein.

Dr. Fishers in Cambodia first alerted Dr. Hogan and his crew at Wonders of the Mekong Project, which works to guard the Southeast Asian river’s aquatic range and is sponsored by the US Agency for International Development, that that they had caught a stingray bigger than anybody had ever seen. Team members rushed to the small river island, referred to as Koh Preah, and lined up three industrial scales. Using a tarp, they hoisted the stingray out of the water and onto the scales to confirm its weight.

The discovery comes lower than a month after one other large stingray – that one weighing 400 kilos – was caught and launched close by. Two different monumental rays have additionally been caught this yr.

“The incontrovertible fact that the world’s largest freshwater fish was caught in the Mekong is exceptional,” Dr. Hogan mentioned. “This is a closely populated area, and the river faces a ton of challenges, together with a lot of fishing.”

In one other first, Dr. Hogan’s crew was capable of match the stingray with an acoustic tag to trace the animal for as much as one yr with an array of 36 underwater receivers that have been additionally just lately put in in a stretch of the river.

“This is the first fish that we have tagged since having the array deployed,” mentioned Dr. Hogan, who can be a analysis affiliate professor at the University of Nevada, Reno. In the months forward, they plan to tag a whole bunch of extra fishes.

With so many huge stingrays caught in current months and all of them feminine, Dr. Hogan believes this stretch of the river and the deep swimming pools it comprises are a essential breeding floor for the species. The space can be house to freshwater dolphins, large soft-shell turtles, large catfish and large barb, which is in the carp household.

“So it is a very distinctive place, and really understudied,” he mentioned. North American and European river techniques obtain much more scientific consideration.

While breaking the world document was not scientifically necessary, Dr. Hogan mentioned that the existence of this fish is an indicator for the well being of its ecosystem. He additionally hoped the discovery reminds the area people how particular this river is, and the way a lot it is in want of saving.

Because of a mixture of things, together with dam development, overfishing and local weather change, massive freshwater fish populations are usually in decline. And many species of massive fish are at risk of disappearing without end.

“In 2020, certainly one of the contenders for the world’s largest freshwater fish, often called the Chinese paddlefish, was declared extinct,” Dr. Hogan mentioned. “That was very unhappy information, and it had me feeling like we have been going to see extra extinctions of those massive fish, slightly than information being damaged.”

Fortunately, the large stingrays are usually not the solely large fish tales of late. In 2021, a record-setting 240-pound lake sturgeon was caught and launched in the Detroit River. And in May, an almost 300-pound alligator gar might have damaged the Texas state document for the freshwater fish, although the angler selected to launch the animal slightly than kill it and convey it in to be weighed.

“When you hear tales about document fish, that is signal,” Dr. Hogan mentioned.

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