Killer Frogs in Golden Gate Park

The African Claw "Killer" Frog
The African Claw “Killer” Frog

Once upon a time there was a tranquil lily pond in Golden Gate Park. It was just off JFK Drive, near the California Academy of Sciences, and was a pleasant home to ducks and fish, turtles, and frogs. Then someone, or something destroyed that equilibrium. The lily pond became a dumping ground for an invasive amphibian, the African clawed frog.

The frogs flourished in the lily pond as they ate the other native species and plants. Unfortunately, they had no natural predators of their own.  In 2003 the Park Department estimated the frog population at 10,000.  By then, California Fish and Game and the San Francisco Recreation and Parks Department knew they had a problem.

Officials worried that the frogs might escape the lily pond and get into other water sources in the city, leading to numbers impossible to control.  Some scientists called for immediately draining the pond but officials dragged their feet and tried other methods.  In 2004 California Fish and Game and some Stanford researchers began a process of collecting frogs with nets and baited traps. By 2007 they had captured about 2,500 frogs with many more to go.

In 2012 California Fish and Game filled the pond with chlorine, covered it with tarps and waited for the remaining frogs and tadpoles to die.  Today the pond is finally drained and spread with lime, another effort to fight the frogs.  Adding further urgency to the mission: a recent study by Stanford researchers has identified this frog as the source of a deadly fungus that has decimated the amphibian population around the world.

How did the frogs get there in the first place? From the 1930’s to 1950’s UCSF and other medical facilities bred these frogs to be used for human pregnancy tests. Later technologies made the frog test obsolete and rumor has it that researchers dumped their unneeded frogs in the nearby pond.

Today chain link fence surrounds the lily pond. But a hopeful sign announces the projected opening of a restored lily pond in Fall, 2014.