A very common question that we get from our students, parents, and teachers is, “Is it safe to eat fish from the Bay?”
This is an excellent question, and an important one for your health. Certain fish can contain contaminants that may affect human and animal health. These contaminants include mercury, PCBs (often used in coolants), and various pesticides, including DDT. How did these things get into the fish?
Contaminants end up in the water through a few different ways. Once upon a time mercury was dumped into the water intentionally! The mercury helped with the mining process during the Gold Rush. Other contaminants and industrial waste also ended up in the water until stricter laws were established to keep our water clean. Contaminants continue to get into the water from industrial sources and runoff from farms, but also from daily human activities.
Many household items and especially cleaning products contain harmful chemicals. Batteries, old thermometers, and fluorescent lightbulbs, are examples of regular household items that contain hazardous waste. These, and most cleaning supplies, need to be disposed of properly at a household hazardous waste stations in order to keep them from getting in the water. If they end up in the dump or in the storm drain, water will wash them down to our rivers and bays.
Through a process called bioaccumulation, living things absorb contaminants (and nutrients) from their environment and food. Organisms toward the base of the food chain may not have much mercury, for example, in their bodies. However, as smaller organisms (and the contaminants they have accumulated) are eaten by larger organisms, those organisms higher up on the food chain gain more and more contaminants. This process is called biomagnification. This is why certain types of animals will have different amounts of contaminants in their bodies than others—and why the recommendation for what to eat varies depending on the fish.
Stewards can help to keep us all healthy by recycling and disposing of household hazardous waste properly!
Check out these tables for recommendations for fish commonly caught in the Bay Area.