San Francisco Bay is one of the nation's largest urban fisheries. Although bay seafood is no longer sold on the retail market, every year thousands of people, the majority of whom are people of color, fish the bay and serve their catch to family and friends. Many are unaware that bay fish are contaminated with a variety of toxic chemicals, including PCBs, dioxin, mercury, chlordane, DDT, and dieldrin. And little progress has been made to clean up the problem and educate the public.
NRDC researchers, relying on data published by the San Francisco Estuary Institute, a research organization, focused on levels of toxic contaminants in fish from San Francisco Bay. They also looked at health advisories, issued by the California Environmental Protection Agency, warning against eating bay fish.
Only limited testing has been done (that is, not all chemicals of concern were tested, nor were all species, and regular monitoring is not carried out), and no clear trends of either increasing or decreasing fish contamination have emerged. Nonetheless, the results are striking. Bay fish are contaminated with toxic chemicals of great concern for public health and for the health of wildlife that eat fish -- harbor seals, for example. Toxic chemicals found in bay fish include PCBs, mercury, chlordane, and such pesticides as DDT and dieldrin.
In 1997, 50 percent of fish sampled in San Francisco Bay exceeded screening values for PCBs and mercury. (A screening value is the tolerable level of a particular contaminant, as determined by the state.) White croaker and shiner surf perch showed high concentrations of PCBs and pesticides, while striped bass and leopard sharks were found to have high levels of mercury. In the same year, 15 percent to 37 percent of samples exceeded the screening values for DDT and chlordane. Fish in Oakland Harbor had significantly higher contamination concentrations than the fish in other areas of the bay. In a number of cases, the level of contamination was well above state and federal health standards.
The California Environmental Protection Agency issues fish-consumption advisories throughout the state. Since 1994, they have had in place advisories covering a range of bay species, including striped bass, shark, shiner surf perch, and white croaker. Currently, only four bay fish -- salmon, anchovies, smelt, and herring -- are not subject to any health warnings regarding consumption.