Native Aquatic Species

Illinois River Chinook
Illinois River, Chinook salmon. Photo by C. Frissell, PRC


PRC works to protect and restore rivers, their watersheds, and the native species that depend on them.  Native aquatic species face serious threats to their viability. Freshwater species are undergoing widespread and accelerated population declines and extinctions.

Freshwater ecosystems have suffered the most calamitous declines of all the earth's major ecosystems.

Rivers, streams, wetlands, and lakes have lost a greater proportion of their species and habitat than any other ecosystem on land or in the oceans.


And of all the earth's major ecosystems, they have suffered the most calamitous declines. Causes of decline include multiple threats from freshwater and land-based sources, including logging, road building, mining, dams, diversions, and grazing.

Although freshwater ecosystems occupy less than one percent of the Earth's surface, they  support an estimated 12 percent of all animal species.  Freshwater ecosystems in their natural state are densely packed with life.  Per unit area or volume, freshwater ecosystems are richer in species than the more expansive terrestrial and marine ecosystems.  Several major groups of organisms depend upon freshwater ecosystems: vertebrates (e.g. fish, amphibians, reptiles, birds, and mammals), invertebrates (e.g. protozoans, myxozoans, rotifers, worms, mollusks, insects, and crustaceans), plants, algae, fungi, bacteria, and other microbes.  Forty percent of known fish species live in fresh water, and freshwater fishes comprise more than half of all vertebrate species on Earth.

Scientists have documented a 50 percent decline in populations of freshwater species over the past 30 years.  Of the 10,000 known species of freshwater fish, 20 percent are threatened, endangered or have become extinct in recent decades.  At least ninety-one freshwater fish species are known to have gone extinct in the last century.  In North America, 40 percent of freshwater species are extinct or at risk of extinction.  In the 20th century, at least 123 North American species of freshwater fish, mollusks, crayfish, and amphibians became extinct.  Based on recent extinctions, an estimated 3.7 percent of freshwater animal species will be lost in North American each decade.  Click here to download American Fisheries Society's most recent list of endangered, threatened, vulnerable, and extinct freshwater and diadromous fishes in North America. (scroll to page 372)

Most of PRC's efforts are geared toward stopping native aquatic species declines, among other things.  Click on the links below to read more about some of our specific programs.

Advocating for Fish Stocking Reform

Protecting Wild Salmon and Steelhead

Save the Coho

Trout Recovery

Amphibian Conservation Initiative

Related Publications 

Download our publication Freshwater Ecosystems in Crisis: A Synopsis in Decline                         


Access all of our publications specifically relating to native aquatic species.




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