Fish Advisory for San Francisco’s Lake Merced (North Lake) Offers Safe Eating Advice for Channel Catfish, Black Bass Species, and Rainbow Trout

Sam Delson
(916) 324-0955 (O)
(916) 764-0955 (C)

SACRAMENTO – A new state fish advisory issued today provides safe eating advice for three species of fish from San Francisco’s Lake Merced (North Lake).

Lake Merced is located in the southwest corner of San Francisco and is comprised of two adjacent discrete waterbodies referred to as the north lake and the south lake. The California Environmental Protection Agency’s Office of Environmental Health Hazard Assessment (OEHHA) developed the recommendations based on the levels of mercury and polychlorinated biphenyls (PCBs) measured in fish collected from the north lake. The advisory does not apply to the south lake.

“Many fish have nutrients that may reduce the risk of heart disease and are an excellent source of protein,” said Dr. Lauren Zeise, director of OEHHA. “By following our guidelines, people can safely eat fish low in chemical contaminants, such as Rainbow Trout from Lake Merced, and enjoy the well-known health benefits of fish consumption.”

When consuming fish from the north lake of Lake Merced, women ages 18-45 and children ages 1-17 may safely eat seven total servings per week of Rainbow Trout. They should not eat black bass species or Channel Catfish. Men 18 years and older and women 46 years and older may safely eat seven total servings per week of Rainbow Trout or one total serving per week of black bass species. They should not eat Channel Catfish.

One serving is eight ounces prior to cooking. For fish fillets, eight ounces is roughly the size and thickness of your hand. Children should be given smaller servings.

Mercury is a naturally occurring metal that is released into the environment from mining and burning coal. Mercury accumulates in fish in the form of methylmercury, which can damage the brain and nervous system, especially in developing children and fetuses.

PCBs are industrial chemicals, and although they were banned in the 1970s, they persist in the environment for many years and are still found in the water from spills, leaks, and improper waste disposal. They accumulate in the skin, fat, and some internal organs of fish, and high levels of exposure have been shown to cause health problems, including cancer in animal studies.

Eating fish in amounts slightly greater than the advisory’s recommendations is not likely to cause health problems if it is done occasionally, such as eating fish caught during an annual vacation.

The health advisory and eating advice for Lake Merced – as well as eating guidelines for other fish species and California bodies of water – are available on OEHHA’s Fish Advisories webpage: Pictorial versions of the fish consumption advice are also available on that page in English and Spanish.

Because of the possibility that catfish in the south lake have similarly elevated PCB concentrations as in the north lake, OEHHA recommends against consuming catfish from either lake. For other species in the south lake as well as species not evaluated from the north lake, please follow OEHHA’s statewide advisory for lakes and reservoirs without site-specific advice.

The Lake Merced recommendations join more than 80 other OEHHA advisories that provide site-specific, health-based fish consumption advice for many of the places where people catch and eat fish in California, including lakes, rivers, bays, reservoirs, and the California coast.

OEHHA is the primary state entity for the assessment of risks posed by chemical contaminants in the environment. Its mission is to protect and enhance public health and the environment by scientific evaluation of risks posed by hazardous substances.