By Patrick J. Kiger
In San Francisco, officials for the Presidio Trust are planning to dump a fish-killing chemical into the Presidio’s historic Mountain Lake, in a last-ditch effort to get rid of big, voracious alien carp, bass and sturgeon who’ve taken over the waters and are wiping out the native species.
The officials in change of the historic former military base turned natural preserve have been driven to this extreme after several years of less toxic measures — netting, trapping, electric stunning and hand-capturing — have failed, according to the San Francisco Chronicle. The chemical they’re using, Rotenone, is plant based and supposedly degrades in three days.
But while poisoning fish sounds like an ecological no-no, officials say the move is necessary to further their plan of turning the 4-acre, 10-to-12-foot deep lake into a protected habitat for the animal and plant species that existed there centuries ago, when the Ohlone Indians and early European settlers were the only ones around.
Since then, though, San Franciscans have helped destroy the lake’s ecosystem, in part by dumping their unwanted pet goldfish and turtles into it. Those cute little fish, some may be surprised to find, are really domesticated carp, and in the wild they can grow to huge size.
According to a March 2014 article on the Bay Nature website, San Francisco State biology graduate student Jonathan Young has spent months with a fishing net, waging an ultimately unsuccessful war against the invasive carp. He told the website that since a single carp can lay up to 2 million eggs in a season, catching them all is an overwhelming task. He’s also caught a five-foot-long sturgeon that actually was bigger than his inflatable raft. The creatures caught by Young ultimately ended up living their lives in ponds in Napa and Sonoma, but now, apparently, such non-lethal measures aren’t enough.