Since 1898 North America has lost at least 39 species of freshwater fish, according to a new study in Bioscience, and an additional 18 subspecies. Moreover, the loss of freshwater fish on the continent seems to be increasing, as the rate jumped by 25 percent since 1989, though even this data may be low.

“Estimates of freshwater fish extinctions during the twentieth century are conservative, because it can take 20-50 years to confirm extinction,” explains lead author, Noel Burkhead, a research fish biologist for the U.S. Geological Survey (USGS), in a press release.



Depiction of an Ash Meadows killifish (Empetrichthys merriami) which went extinct in the 1950s. Image by: David Starr Jordan.

Burkhead calculated that the rate of freshwater fish extinction on the continent is at least 877 times faster than in the fossil record, where a freshwater fish vanished every 3 million years or so on average. Currently, 1,213 freshwater fish are found in Northern America.

Over the last century fish have been pushed to extinction by dams, pollution, invasive species, channelization of rivers, and other impacts. But as bad as fish have it, freshwater snails and mussels are going extinct at even quicker rates.

Worldwide, freshwater species are more imperiled than other groups. A scientist in 2009 calculated that freshwater species were currently four to six more likely to go extinct than their marine and land relatives. For decades, scientists have warned that the Earth may soon, or already, be facing a mass extinction due to human impacts.

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