The US National Oceanic and Atmospheric Administration is considering a proposal to expand the boundaries of two federal MPAs along the coast of northern California – Cordell Bank National Marine Sanctuary and the Gulf of the Farallones National Marine Sanctuary. Designated in the 1980s, the sanctuaries currently cover roughly 1800 square miles (4700 km2) of ocean. The expansion area, proposed by the Administration of President Barack Obama last December, would cover an additional 2500 square miles (6500 km2) – more than doubling the sanctuaries’ size.

Although the expansion, as proposed, would not impact current fishing activity, it would apply a permanent ban on offshore oil drilling in the expansion area. The proposal is under public review, with comments welcome through 1 March 2013.

When MPA boundaries are changed to help ensure the sustainability of particular ecosystem services, it is a form of ecosystem-based management. In the case of this proposed expansion, ecosystem-based arguments provide the basis for it. “The expansion area includes the entire upwelling zone that feeds the existing sanctuaries,” says Lance Morgan, Chair of the Cordell Bank National Marine Sanctuary Advisory Council. “So the addition provides for continuity of this critical environmental process that is the basis for the rich productivity and concentration of marine life at Cordell Bank and the Farallon Islands – from rockfish and sea urchins to seabirds and marine mammals.”

Richard Charter, Vice-Chair of the Gulf of the Farallones National Marine Sanctuary Advisory Council, considers the upwelling zone to be among the most productive in the world. “There is ecosystem science that confirms higher concentrations of certain large marine predators at various locations within the proposed expansion area – a probable indication of the presence of prolific prey species, reinforcing the need to protect the rich biota in the region,” he says. A ban on offshore drilling in the area is needed, he says, because any offshore drilling accident would threaten the ecosystem and its services. “A significant oil spill would be virtually impossible to clean up in the often hostile sea-states and extreme weather conditions that can exist in this area. And nearby sensitive estuaries are configured in ways prohibitive of booming and other site-specific response measures in the event of an oil spill.”

Previous attempts to expand the sanctuary boundaries stalled due to political concerns about blocking future offshore oil and gas development. (Richard Charter describes the development of the current proposal here.) To learn more about or comment on the current proposal, go to