A Kansas State University researcher says the prolonged North American drought is taking a toll on some species of fish and affecting their long-term viability.
Biology professor Keith Gido says a few species have disappeared, including the silver chub that was once found in a southern Kansas river.
He said a survey found 300 of the fish in the summer of 2011 but only three in 2012 - and none in a sampling this spring.
Gido says similar results have been found in ecosystems in Colorado and New Mexico as rivers become more fragmented and difficult for young fish to develop and survive.
Researchers say efforts are needed to conserve remaining waterways and reduce the number of non-native, predatory fish.