Authorities are warning that bass at several of the most popular fishing destinations in Arizona and California have accumulated excessive mercury levels.
In California, 180 reservoirs are contaminated with high mercury levels. The State Water Resources Control Board took fish samples from more than 300 of the state’s reservoirs to make that determination. The board is now urging the reservoirs’ owners to post voluntary warnings about eating the fish that are at the top of the food chain, such as bass. These fish tend to accumulate the most mercury, posing a particular risk to children and pregnant women.
Even though the warnings are intended to help protect human life, those who depend on the income brought by tourists and sportsmen to the bodies of water in question are reluctant to post voluntary warnings and draw attention to the matter.
Big Bear Lake, which is nestled in the San Bernardino Mountains, welcomes millions of visitors each year for recreational activities that include not only fishing but also sailing and jet skiing. Some anglers believe that the bass are being unfairly singled out in an effort to protect the endangered and native species they consume. On the other hand, one real estate agent in Big Bear points out that mercury advisories could adversely affect property values, saying that he would not be opposed to getting rid of the bass altogether to skirt the problem.
Other reservoirs that have been classified as “mercury impaired” include Irvine Lake, Lake Hodges, Silverwood Lake, El Capitan Reservoir, Lake Arrowhead, Crowley Lake, and the aptly named Bass Lake. It was Sherwood Lake in Ventura County, however, where the highest levels of methylmercury in Southern California were found. Bass there measured 0.65 milligrams of methylmercury per kilogram.
A statewide mercury control program is currently being developed by state water authorities in conjunction with nine different local water quality control boards, but mandatory health advisories are said to be at least two years away.
Mercury consumption dangerous for humans
Mercury is a strong neurotoxin that can cause serious health consequences in humans. It is absorbed by bacteria, which transforms it into its organic form, methylmercury. As it works its way up the food chain, it accumulates, which means eating bigger fish places people at a higher risk.
Seafood is the biggest single dietary source of mercury. A 2015 study published in Environmental Toxicology and Chemistry found that the levels of mercury in Pacific yellowfin tuna have risen 3.8 percent each year since 1998. Other studies have shown that the chemical fingerprint of the mercury found in yellowfin tuna and swordfish is tied to Asian coal-burning plants. The mercury emitted by these outdated factories is capable of traveling great distances, and prevailing winds are blamed for carrying it clear across the ocean.
Safe consumption guidelines set by authorities in Arizona
In Arizona, meanwhile, a warning has been issued for largemouth bass at Scott Reservoir near Pinetop-Lakeside. After discovering elevated mercury levels in tissue samples from fish in the reservoir, the Department of Environmental Quality announced that adults should eat fewer than 2.4 ounces of this fish each week, while children should not consume more than 2 ounces per month. The warning does not apply to recreational activities because the mercury levels in the fish are a lot more concentrated than they are in the water.
While you can’t test every fish you catch or are served in a restaurant for mercury, you can avoid eating some of the fish that are known to accumulate high amounts of it. In addition to bass, fish such as marlin, king mackerel, Bluefin tuna, swordfish, and bluefish are all known to have high levels of mercury. You can also eat foods that can help chelate heavy metals, such as onions, cilantro, spirulina and Brazil nuts. It’s also important to seek out and heed local warnings if you are consuming fish you caught yourself.