Almost two in five of North American freshwater fish species are in danger of extinction, according to a recent evaluation of the conservation status of the freshwater fishes of North America.
The study is the most detailed of its kind to be conducted in 20 years and is published in a recent issue of the journal Fisheries.
A U.S. Geological Survey-led team of scientists from the United States, Canada and Mexico examined the status of continental freshwater and diadromous (those that migrate between rivers and oceans) fish species from North America and concluded that 700 species are listed as vulnerable (230), threatened (190) or endangered (280), with another 61 presumed extinct or considered extirpated from natural habitats.
This represents about 39% of the described fish species of the North American continent (defined as Canada, the United States and Mexico in this study). The number of imperiled species represents a 92% increase over the last such survey by the American Fisheries Society conducted in 1989, which listed only 364 species.
The fishes identified as being most at risk are the salmon and trout of the Pacific Coast and western mountain regions; minnows, suckers and catfishes throughout the continent; darters in the southeastern United States; and pupfish, livebearers, and goodeids in Mexico and the southwestern United States. Areas where the fish fauna have been identified as being the most at risk include the southeastern United States, the mid-Pacific coast, the lower Rio Grande and basins in Mexico that do not drain to the sea.
According to Mark Myers, director of the USGS, "reshwater fish have continued to decline since the late 1970s, with the primary causes being habitat loss, dwindling range and introduction of non-native species. In addition, climate change may further affect these fish."
For more information, see the paper: Jelks, HL, SJ Walsh, NM Burkhead, S Contreras-Balderas, E Daz-Pardo, DA Hendrickson, J Lyons, NE Mandrak, F McCormick, JS Nelson, SP Platania, BA Porter, CB Renaud, JJ Schmitter-Soto, EB Taylor, and ML Warren, Jr. (2008) Conservation status of imperiled North American freshwater and diadromous fishes. Fisheries 33, pp. 372"407.