Medary.com

Yahoo News/AP:

DENVER - A 20-year government effort to restore the population of an endangered native trout in Colorado has made little progress because biologists have been stocking some of the waterways with the wrong fish, a new study says.

Advances in genetic testing helped biologist discover the error, which was called a potential black eye, but they said there is still hope for restoring the greenback cutthroat trout.

The three-year study, led by University of Colorado researchers and published online in Molecular Ecology on Aug. 28, said that five of the nine populations believed to be descendants of the endangered trout were actually the more common Colorado River cutthroat trout, which look similar.

Alternate headline:  Scientists can, occasionally, be wrong.  For a long time.

But hey, it's only trout.