Safe For Eating

Unfortunately, the Bay and Delta are not entirely fishable. Contaminants, especially mercury and PCBs, that made their way from land to the Estuary decades ago, persist and cause concentrations in some fish to be above safe levels. The Safe to Eat assessment is based on concentrations in selected fish species that are commonly consumed and regularly monitored. Striped bass and black bass are the key species illustrating the severity of the problem for mercury, and shiner surfperch show the severity for PCBs. California halibut and jacksmelt show that some species have lower concentrations and are safer for consumption.

Mercury and PCB concentrations in Estuary fish present a health risk to fish consumers, especially children and fetuses, who can be exposed via their mother’s diet. Mercury can negatively impact brain development in unborn babies and children, potentially harming learning ability, language skills, attention, and memory. Mercury can also cause neurological impairments in adults. Men, women, and children are all at risk from PCBs, which can cause developmental problems and cancer.

Fish advisories issued by the California Office of Environmental Health Hazard Assessment (OEHHA), which recommend limited consumption of fish from the Bay, have been in place since the 1990s. The latest version of the Bay advisory advises people not to eat shiner surfperch due to high concentrations of PCBs. In addition, it recommends avoiding consumption of striped bass, white sturgeon, shark species, and several smaller species by the sensitive population (women aged 18-49 years and children aged 1-17 years) due to high levels of mercury and PCBs. Consumption advice for the Delta from OEHHA is driven primarily by high concentrations of mercury. The sensitive population is advised not to consume striped bass, black bass, catfish, Sacramento pikeminnow, or white sturgeon.

 

Progress toward the goal of a fully fishable Estuary has been slow. The Regional Monitoring Program for Water Quality in San Francisco Bay has been monitoring contaminants in Bay fish since 1997, following up on a pilot study conducted by the Bay Protection and Toxic Cleanup Program in 1994. Over this timespan, mercury and PCBs have shown only modest signs of long-term decline. Evidence for declines has been stronger for other contaminants of concern, such as PBDEs and dioxins.

The San Francisco Bay Regional Water Quality Control Board has established Total Maximum Daily Loads (TMDLs)–pollution limits and cleanup plans–for mercury and PCBs, and the Central Valley Regional Water Quality Control Board has a TMDL for methylmercury. Concentrations in fish are the key benchmarks in these TMDLs. The TMDLs have been in place for approximately 15 years and have prompted actions to reduce mercury and PCB inputs to the Estuary. Progress is slow, though, because the mercury and PCB contamination was spread widely across the land surface of the Estuary watershed, reductions of inputs have been limited, and the contamination has been mixed into the sediment and trapped in the Estuary.