The guidelines for safely eating fish caught in California waters are public health recommendations. These advisories are detailed consumption limits that vary by water body, fish species, and the consumer’s age or reproductive status, rather than simple “do not eat” lists. The goal is to balance the nutritional benefits of eating fish, such as omega-3 fatty acids, with the risks from environmental pollutants. These recommendations apply specifically to sport fish caught by anglers, not commercially sold seafood, which is regulated by different agencies.
Primary Contaminants Driving the Advisories
Fish consumption advisories across California waters are primarily driven by two toxic substances: mercury and Polychlorinated Biphenyls (PCBs). Mercury is a naturally occurring element, but its presence in waterways is increased by historical gold mining and atmospheric fallout from coal-burning power plants. Once in the water, it converts into methylmercury, a highly toxic form that bioaccumulates up the food chain. Older, larger predatory fish carry the highest concentrations.
Methylmercury is a neurotoxin that harms the brain and nervous system, particularly affecting developing fetuses and young children. Therefore, advice for women of childbearing age and children is the most restrictive for fish species high in mercury.
PCBs are human-made chemicals once used widely in industrial applications before being banned in the late 1970s. They persist in the environment because they break down slowly, accumulating in the fatty tissues of fish. Exposure to PCBs is associated with cancer risk and neurotoxicity.
In localized areas, such as Southern California coastal waters, advisories are also influenced by legacy pesticides like DDTs. Like PCBs, these substances are fat-soluble and concentrate in the skin, fat, and internal organs of fish. Consumption advice often includes preparation tips, such as removing the skin and fat before cooking, to reduce exposure to these contaminants.
Statewide and Coastal Consumption Guidelines
California issues general, statewide advisories for coastal areas and water bodies lacking localized studies. These broader guidelines help anglers make informed choices when fishing in the open ocean or general stretches of rivers.
Marine species frequently focus on mercury bioaccumulation in long-lived, larger ocean predators. For example, species like sharks and certain types of rockfish are consistently listed in the “Do Not Eat” or most restricted consumption categories for sensitive populations due to high mercury levels.
Advisories for specific coastal and bay environments, such as San Francisco Bay, often involve both mercury and PCBs. Bottom-dwelling species like White Croaker have historically shown elevated levels of PCBs and DDTs, leading to specific warnings. Bay advisories feature a gradient of advice, ranging from “Seven Servings Per Week” for cleaner species like Northern Anchovy, down to “Do Not Eat” for others.
The two primary consumer groups—sensitive populations (women aged 18 to 49 and children) and the general population (men and older women)—receive different advice. The sensitive group’s advice is always more conservative, allowing fewer or smaller servings per week. A serving is standardized as an eight-ounce portion of fish before cooking.
Specific Freshwater Advisories
Inland waters, including California’s lakes, reservoirs, and rivers, are covered by highly localized advisories. These warnings are necessary because contaminant levels can vary drastically, even between two species caught from the same body of water.
A major source of contamination in many freshwater systems is the legacy of the Gold Rush, which left extensive mercury deposits. This mercury is now present in reservoirs and rivers throughout the Sierra Nevada and Central Valley, impacting species like bass and catfish.
For example, advisories in a specific lake may recommend that sensitive populations “Do Not Eat” Black Bass or Bullhead species, while allowing several servings per week of Rainbow Trout. The predatory Black Bass accumulates more methylmercury, while smaller trout often contain lower contaminant levels.
The Sacramento-San Joaquin River Delta has specific warnings due to both mercury and PCBs. Advice for the Delta can be restrictive, with “Do Not Eat” warnings for species like Striped Bass or White Sturgeon for sensitive groups. These localized warnings reflect the history of industrial runoff and sediment contamination.
Advisories for freshwater species are often size-dependent, with smaller fish generally having lower contaminant levels than larger, older individuals. Anglers must consult the specific advisory for the exact lake or river where they are fishing.
How to Access the Most Current Official Advice
The California Office of Environmental Health Hazard Assessment (OEHHA) is the state agency responsible for developing and issuing all official fish consumption advisories. OEHHA maintains the most current database of safe eating guidelines for California’s sport fish.
The most effective way to determine advice for a specific location is to use OEHHA’s interactive Fish Advisory Map, which covers over 150 site-specific water bodies. By clicking on a lake, reservoir, river, or coastal area, anglers can immediately access detailed guidance for the fish species found there.
For water bodies without a specific advisory, OEHHA provides applicable statewide guidelines for lakes/reservoirs, rivers/streams, and coastal areas. OEHHA occasionally updates these advisories based on new scientific monitoring data or issues temporary warnings for biotoxins, such as those caused by harmful algal blooms.
The agency’s advice is presented in fact sheets that clearly separate the consumption limits for the two primary population groups. Following these guidelines helps anglers maximize the health benefits of their catch while minimizing contaminant exposure.