Scientists are concerned about the hellbender salamander's declining population.

According to Associated Press, hellbenders can be found in 16 different U.S. states. They live in rivers and streams identifiable by their plentiful rocks and fast currents. The salamanders, however, are becoming harder to find. For example, hellbenders used to be found in many rivers and streams in the southern half of Indiana. Now, they can only be found in the basin of the Blue River.

"These are animals that live up to 30 years in the wild, so if you have populations declining, that alerts us that there could be a problem with the water quality," Rod Williams, an associate herpetology professor at Purdue University who has been studying hellbenders in Indiana for almost 10 years, explained.

There are some areas that seem to have steady hellbender populations, but nearby residents report strange activity, such as the salamanders being poisonous or eating baby trouts instead of their usual crayfish diet. In addition, anglers reportedly "kill them on sight" occasionally, AP reports.

The U.S. Fish and Wildlife Service is currently assessing the eastern hellbender, one of the two subspecies of the hellbender, in order to determine if it should be put on the federal endangered species list.

"There's nothing else like them in North America," Jeromy Applegate, the federal biologist in charge of the assessment, said

Meanwhile, the Ozark hellbender, the other hellbender subspecies, has been on the endangered species list since 2011 after suffering a 75 percent population cut. The salamander lives in Arkansas and Missouri with an estimated 1,200 left in the wild.

The Missouri Department of Conservation has collaborated with the St. Louis Zoo to hatch and raise 3,000 Ozark hellbenders.

"It buys us time to figure out and address the threats," Trisha Crabill, a U.S. Fish and Wildlife Service biologist, said.

Hellbenders are North America's largest salamander and reach up to over two feet in length. The amphibians are especially important because they breathe through their skin, making things like pollution and silt stand out and thus creating a profile for the river or stream in which it lives.

"If nothing else, if people don't appreciate the animal for itself, that it has value to the world, then it can serve as a messenger," Crabill said. "It can tell us what's going on in the river."
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