Bay Nature magazineSpring 2012


Cargo Ships Keep Bringing Invasives to the Bay

June 7, 2012

Four new invasive species have recently taken up residence in San Francisco Bay, according to the state Department of Fish and Game’s 2011 Invasive Species Report []. With at least 300 exotic species already thriving here, the Bay and estuary make up the West Coast’s most invaded estuary, so adding four more exotic species might not seem to be a big deal. But a study by Fish and Game and the Smithsonian Environmental Research Center has confirmed what might be obvious: The estuary conveys invasive species into the rest of California. Their research shows that 61 percent of California’s 257 established nonnative aquatic species were first detected in San Francisco Bay.

Ballast water released from ships is a primary source of this living pollution, and a battle over how to best regulate it has been raging for over a decade. Since 1999, conservationists have pressured the U.S. Environmental Protection Agency (EPA) to address aquatic invasions under the Clean Water Act and to consider them as seriously as they do oil spills and toxic releases. Forced to act by litigation, the EPA has issued a revamped Vessel General Permit that will require ships to provide onboard water treatment. The rule will go into effect in December 2013.

Conservationists, far from satisfied, are concerned that on-ship treatment will be difficult or impossible to verify. Lawrence Kolb, a retired 30-year staffer at the San Francisco Bay Regional Water Control Board, says a facility on shore or on a barge would be more effective and less costly than installing treatment systems on thousands of ships, a point also noted by the EPA’s advisory board.

While a number of groups and agencies work to control invasive species, the best strategy is to keep them from escaping in the first place. “Once they’re on the West Coast, there’s little we can do to control them or to stop their spread from one bay to another,” says Andrew Cohen, director of Center for Research on Aquatic Bioinvasions.

About the Author

Writer Aleta George trained as a Jepson Prairie docent in 2009. In addition to writing Bay Nature's Ear to the Ground column, she has written for Smithsonian, High Country News, and the Los Angeles Times.