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Rio Grande Water Quality Studies/Silvery Minnow

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The Rio Grande Silvery Minnow

The Rio Grande silvery minnow (Hybognathus amarus), a federally endangered species, is found in the mainstream of the Middle Rio Grande. The decline of the minnow has been attributed in part to water-quality degradation within the Rio Grande. In an effort to better understand the decline of the minnow, the New Mexico Ecological Services Field Office in conjunction with the New Mexico Fishery Resources Office, and Water Resources Office, designed a field-based study to obtain the requisite scientific information with regard to water quality conditions in silvery minnow habitat along the middle Rio Grande valley. Assessments have been conducted approximately every other week during July and August at sampling sites populated with Rio Grande silvery minnows and at sites where they no longer occur. This study represents essential data necessary to plan for reintroduction of fish in areas that are wet during normal water operations as well as understanding contributing factors in their decline. The assessment includes: development of a fish monitoring plan, a sampling and analysis plan; and a quality-assurance project plan; fish monitoring; fish health evaluations; whole stream productivity, review and analysis of historical data; collection and analysis of water, suspended-sediment, bed-material, and fish-tissue samples; toxicity testing; and interpretation of the resulting data. This multi-program and integrated approach will result in a tighter partnership and understanding between scientists, policy makers, and regulators as to the biological effects associated with various water quality conditions as compared with traditional water only analyses. Water quality conditions can then be considered when making management decisions on silvery minnow habitat, reintroduction, ecosystem management. The New Mexico Ecological Services Field Office has also continued to work closely with the US Geological Survey, Biological Resources Division, to conduct the necessary Rio Grande silvery minnow toxicity studies. The purpose of this research is to evaluate the effects of long-term exposures to effluents and receiving waters in the middle Rio Grande.

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This webpage was last modified on: December 21, 2005

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