High Levels Of Mercury Found In Fish In Remote National Parks

Unhealthily high levels of mercury have been found in fish in national parks in Alaska and the West, proving that even the most remote lakes and streams in the U.S. aren’t immune to mercury pollution.

Researchers from the U.S. Geological Survey and National Park Service released a report Thursday that found 5 percent of the freshwater fish sampled in 21 western national parks had levels of mercury that were high enough to trigger toxic responses from the fish themselves, potentially endangering their health and lives. In addition, 35 percent of the fish sampled had enough mercury in them to impact the health of some predatory birds, and 68 percent of fish had mercury levels above the recommended amount for “unlimited consumption” by humans.

The researchers said in their report that the levels of mercury in some national parks were alarming because they occurred in small fish — organisms that should have the least amount of mercury in their systems, because the higher fish are on the food chain, the more mercury they’re expected to have.

Zion, Capital Reef, Wrangell-St. Elias, and Lake Clark National Parks all contained sites in which most fish exceeded benchmarks for the protection of human and wildlife health,” the report reads. “This finding is particularly concerning in Zion and Capitol Reef National Parks because the fish from these parks were speckled dace, a small, invertebrate-feeding species, yet their Hg [mercury] concentrations were as high or higher than those in the largest, long-lived predatory species, such as lake trout.”

The report illustrates the widespread effect human activity has on even the most far-flung regions of the planet. Mercury is produced through the combustion of coal and other fossil fuels, as well as by cement and metals manufacturing and mining operations. Half of the U.S.’s mercury air pollution is produced by power plants and other industrial sources, and if the mercury originates far from remote areas like national parks, it can be carried through wind currents and fall to the ground through rain, snow or dust particles.

“This is a wake-up call,” Colleen Flanagan Pritz, co-author of the report and NPS ecologist said in a release. “We need to see fewer contaminants in park ecosystems, especially contaminants like mercury where concentrations in fish challenge the very mission of the national parks to leave wild life unimpaired for future generations.”

Already in the U.S., more than 16 million lake acres and one million river miles are under fish consumption advisories because of their high levels of mercury, according to USGS data, and 81 percent of all EPA-issued fish consumption advisories are due to mercury contamination.

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