Environmental Contaminants and their effects on fish in the Colorado River Basin

Fish in the nation's rivers are exposed to many classes of environmental contaminants. Some of these contaminants accumulate in fish tissues and are passed on to consumers, such as other fish, wildlife, and humans. These compounds, and many others which do not accumulate in tissues, may weaken the fish's ability to maintain healthy and viable populations. By measuring the effects that contaminants have on fish, as well as contaminant concentrations in tissue, we can evaluate the quality of the habitat relative to contamination. In the summer and fall of 2003, the U.S. Geological Survey evaluated the effects that contaminants have on organisms by measuring several physiological and biochemical functions in resident fish species in the Colorado River Basin. Assessing contaminants effects in the Colorad River Basin is important for the protection of species dependent on the unique ecosystem and the people utilizing its resources. Sources of contaminants in the Colorado River Basin i