On Oct. 9, biologists electrofishing in Grand Canyon National Park caught a razorback sucker -- the first one seen in the park in 20 years. The endangered fish, known for its distinctive humpback, huge size (up to three feet long!) and long life (40-plus years!) was once common in the Colorado River and its tributaries.

But its population has plummeted since the construction of dams, which lowered water temperatures in the river, and increased predation by exotic species. Journalist Hillary Rosner covered the plight of the fish in her 2010 feature story, “One tough sucker.” (She also won a sweet science writing award for that story -- check it out!)

As Rosner reported, sucker populations are now nearly limited to reservoirs on the Lower Colorado, and its survival depends on re-stocking programs. That's why the discovery of the fish in the Grand Canyon was such a surprise.

Biologists believe the fish swam upstream 50 miles from Nevada’s Lake Mead, and are trying to figure out what the discovery means for the embattled species. “What’s different now, and how do we maintain it?” asked Martha Hahn, science director for Grand Canyon National Park.

Here's what a razorback sucker looks like. 

Pretty nifty to find one of these swimming around in the Colorado River, eh?

Stephanie Paige Ogburn is the online editor at High Country News.

Emily Guerin contributed research.

Image of Hoover Dam courtesy Shutterstock.

Image of sucker courtesy U.S. Fish and Wildlife Service.