date:Aug 14, 2012
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 US Geological Survey, 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 nine per cent of the Earth's freshwater fish diversity. At least 57 North American species and subspecies, and three