Scientists are planning to kill thousands of bullfrogs next month as the federal government drains a major lake near Nogales to get rid of mercury contamination.
As Peña Blanca Lake empties, authorities plan to go after not only the bullfrogs living there, but bullfrogs living up to five miles away.
The reason: Bullfrogs are a major competitor to native lowland frogs and Chiricahua leopard frogs. The native populations have been dwindling, in part because non-native bullfrogs not only eat leopard frog tadpoles but carry a fungal disease that can be deadly to leopard frogs.
But exact plans for the removal are uncertain and finances are up in the air.
Several biologists have submitted a request for a $40,000 state grant to pay trained professionals to do the work of removing 2,000 to 5,000 bullfrogs.
People are also reading…
The draining of Peña Blanca Lake is scheduled to start Oct. 6. It should take 30 to 40 days.
The lake will be closed to the public for some time afterward while authorities also dredge and remove hundreds of thousands of tons of mercury-tainted sediment from the lakebed. The mercury came from an old upstream gold mill.
The request for the bullfrog removal grant is still pending. But the Arizona Game and Fish Department plans to go ahead with the removal, with or without that money, in an effort involving volunteers, federal agencies, an environmental group and University of Arizona scientists.
"I think our ability to eliminate bullfrogs is probably the most important conservation step we could take to recover leopard frogs in that area," said Tom Jones, Game and Fish's amphibians-and-reptiles program manager. "Bullfrogs are the scourge of amphibian conservation."
He said if the grant doesn't come through, the state will find money elsewhere.
But if the grant request fails, Phil Rosen, a UA research scientist who helped prepare it, said he would tend to oppose a removal relying heavily on volunteers because the job is tricky and difficult.
He and several other biologists used close to $50,000 in grant money a few years ago in a bullfrog-removal project that lasted three years. It helped recover populations of the threatened Chiricahua leopard frog at Buenos Aires National Wildlife Refuge south of Tucson, he said.
"We should do it right and do it once, and if we have to do it again because we've done our best and failed, fine. If we do it half-baked, and kill 5,000 to 10,000 bullfrogs and it didn't work, it's just irresponsible," Rosen said.
