Fish consumption is the major route of mercury exposure in the United States, but there are many health benefits of eating fish that is low in mercury, PCBs, and other contaminants. Fish is high in protein and low in fat, and is an important source of omega-3 fatty acids, which support heart health and brain functions. But until now, there has been little known about mercury levels in Humboldt Bay fish and shellfish.
In 2016, Baykeeper was awarded a grant from the California Environmental Protection Agency to sample local fish and shellfish. Working with fisheries consultant Ross Taylor, the Wiyot Tribe, and dozens of local anglers, we spent nearly two years catching Humboldt Bay fish to sample.
Our results include both good news and bad news. In short, the best way to avoid mercury exposure while eating lots of healthy local fish is to eat small, short-lived species that eat lower on the food chain, since mercury accumulates in older predatory fish. Salmon, oysters, and clams are very low in mercury. Dungeness crab and locally caught albacore are relatively safe in moderation, but California halibut, lingcod under 10 pounds, and Pacific halibut under 40 pounds should be eaten less frequently. Sharks and some species of rockfish are long-lived predators that should be avoided entirely due to high mercury levels. Black rockfish, also known as black snapper, is a shorter-lived species that can be safely eaten more frequently.
Our results are especially important for people who eat more fish than the average Americans: including tribal members; sport and subsistence anglers; commercial fishermen; and anyone who tends to freeze, smoke, or pressure cook and can fish to eat and feed their families year round, since they often consume many meals from one large animal.
There are no known local sources of mercury in the Humboldt Bay area. Mercury was used in historic gold mining in the Klamath, Trinity, and Russian Rivers, but is not known to have been used near Humboldt Bay or in the adjacent Eel and Mad River watersheds.
The primary source of mercury in the U.S. is pollution from coal-burning power plants around the world. Mercury is emitted into the atmosphere wherever coal is burned and deposited across western North America. A recent study found that coastal fog deposits mercury at higher levels than rainwater in Central California.
To download the printable guidelines and the full report, visit www.humboldtbaykeeper.org.
On the Water Humboldt Bay Cleanups
On April 22, an enthusiastic crew of 20 Baykeeper volunteers, 16 Coast Seafood employees, and three Humboldt Bay Aquatic Center guides paddled over to Indian Island and, in just a few hours, removed more than 3,000 pounds of trash! Thanks to everyone who spent part of their weekend keeping trash out of Humboldt Bay! We’ll do it again on Coastal Cleanup Day September 15—all gear provided and no paddling experience necessary (and it’s free!). Join us!