Translocating frogs to lakes where disease wiped out previous populations may be the key to recovery

November 19, 2018 by Shelly Leachman, University of California - Santa Barbara

In a box, within a canister, surrounded by snow, tucked tightly into a backpack strapped to one determined ecologist. Twenty at a time they travel, these unassuming, iconic frogs, departing places where they're thriving for sites from which their species has vanished. Their mission: population recovery.

In ecology-speak this is known as translocation—capturing, transporting, then releasing animals somewhere else, often to conserve the species. And when it comes to the Sierra Nevada yellow-legged frog, amphibian residents of Yosemite National Park left devastated by the chytrid fungus Batrachochytrium dendrobatidis (Bd), it appears to be working.

UC Santa Barbara ecologist Roland Knapp has been leading a team of field crews—in collaboration with the National Park Service, U.S. Geological Survey and U.S. Fish & Wildlife Service—to save these frogs by reintroducing them to lakes from which they have disappeared because of Bd. The results of these novel experiments might provide important insights into how amphibian populations worldwide that have been impacted Bd might be recovered.

"Sierra Nevada yellow-legged frogs were devastated by Bd following its spread across these mountains," said Knapp, a research scientist based at the UCSB-managed Sierra Nevada Aquatic Research Laboratory in Mammoth Lakes. "But a few populations survived and appear to be evolving some degree of resistance to this pathogen, allowing them to recover despite the ongoing presence of Bd. Using frogs from those recovering populations to reestablish populations that were previously eliminated by Bd—that hasn't been done much before. It's good news for frogs for sure."

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