North American freshwater fishes race to extinction

Aug 10, 2012

North American freshwater fishes are going extinct at an alarming rate compared with other species, according to an article in the September issue of BioScience. The rate of extinctions increased noticeably after 1950, although it has leveled off in the past decade. The number of extinct species has grown by 25 percent since 1989.

The article, by Noel M. Burkhead of the , examines North American freshwater fish extinctions from the end of the 19th Century to 2010, when there were 1213 species in the continent, or about 9 percent of the Earth's freshwater fish diversity. At least 57 North American species and , and 3 unique populations, have gone extinct since 1898, about 3.2 percent of the total. Freshwater species generally are known to suffer higher rates of extinction than .

Extinctions in fishes are mostly caused by loss of habitat and the introduction of nonindigenous species. In North America, there are more species in a typical drainage to the east of the Great Continental Divide than to the west, where a greater proportion of species have gone extinct or are found nowhere else.

Estimating the number of extinctions relies on scrutiny of historical records and careful estimation procedures, since the last populations of a species are often recognized as such only in hindsight—there is typically a lag of several years from the last observation of a species and its estimated year of extinction. Estimates are complicated by the fact that, on average, 6.7 new species are discovered each year, and occasionally a species thought to have gone extinct is "rediscovered." Nonetheless, Burkhead concludes that between 53 and 86 species of North American freshwater fishes are likely to have gone extinct by 2050, and that the rate of extinction is now at least 877 times the background extinction rate over geological time.

Explore further: Team defines new biodiversity metric

add to favorites email to friend print save as pdf

Related Stories

Bird species are saved from extinction

Aug 28, 2006

The first global audit of threatened species shows 16 species of birds nearly extinct in the mid-1990s have been saved, some increasing tenfold in number.

Recommended for you

Team defines new biodiversity metric

21 hours ago

To understand how the repeated climatic shifts over the last 120,000 years may have influenced today's patterns of genetic diversity, a team of researchers led by City College of New York biologist Dr. Ana ...

Changes in farming and climate hurting British moths

Aug 29, 2014

Britain's moths are feeling the pinch – threatened on one side by climate change and on the other by habitat loss and harmful farming methods. A new study gives the most comprehensive picture yet of trends ...

User comments : 0