UC Berkeley post-doctoral fellow Vance T. Vredenburg showed that introduced trout have devastated native frog populations over the past 50 years in formerly fish-free high-Sierra lakes, but that removing the fish can allow the frogs to flourish once more.
Vredenburg's study was published this week in the online edition of the Proceedings of the National Academy of Sciences.
"The mountain yellow-legged frog used to be the most common inhabitant of the high Sierra, but frog populations have declined dramatically enough to put it on the endangered species list," said Vredenburg, who works at the campus's Museum of Vertebrate Zoology. "I'm not saying that other things didn't cause a decline as well, but this report shows that most of the problem came from fish."
Though anglers might resist efforts to remove trout from Sierra lakes, Vredenburg's preliminary data and the results of an earlier survey of Sierra frog populations were critical pieces of evidence that led the park service and Fish and Game to consider that approach, at least on a limited basis.
"People want their trout, but they don't realize what they're getting along with their trout - changed ecosystems, diseases and all sorts of things," noted David Wake, a UC Berkeley professor of integrative biology who organized the first international conference on amphibian decline in 1990.
In a 1915 survey of wildlife in the Sierra Nevada, UC Berkeley biologist and museum director Joseph Grinnell complained that mountain yellow-legged frogs (Rana muscosa) were so abundant that his survey team was stepping on them. Today there are probably few
Contact: Robert Sanders
University of California - Berkeley