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Use of Fish as Environmental Indicators
Fish have been used for many years to indicate whether waters are clean or polluted, doing better or getting worse. Knowing just whether fish live in the waters is not enough - we need to know what kinds of fish are there, how many, and their health. Fish are excellent indicators of watershed health because they:
- live in the water all of their life
- differ in their tolerance to amount and types of pollution
- are easy to collect with the right equipment
- live for several years
- are easy to identify in the field
Here are more specific attributes of fish that make them desirable components of biological assessments and monitoring programs.
The figure above shows the use of fish in bioassessments (2001 base year). Fish were used in 41 state and tribal programs. From "Summary of Biological Assessment Programs and Biocriteria Development for States, Tribes, Territories, and Interstate Commissions: Streams and Wadeable Rivers (EPA-822-R-02-048)"
Accurate assessment of environmental health
- Fish populations and individuals generally remain in the same area during summer seasons
- Communities are persistent and recover rapidly from natural disturbances
- Comparable results can be expected from an unperturbed site at various times
- Fish have large ranges and are less affected by natural microhabitat differences than smaller organisms. This makes fish extremely useful for assessing regional and macrohabitat differences
- Most fish species have long life spans (2-10+ years) and can reflect both, long-term and current water resource quality
- Fish continually inhabit the receiving water and integrate the chemical, physical, and biological histories of the waters
- Fish represent a broad spectrum of community tolerances from very sensitive to highly tolerant and respond to chemical, physical, and biological degradation in characteristic response patterns
Visibililty
- Fish are highly visible and valuable components of the aquatic community to the public
- Aquatic life uses and regulatory language are generally characterized in terms of fish (i.e., fishable and swimmable goal of the Clean Water Act)
From "Summary of Biological Assessment Programs and Biocriteria Development for States, Tribes, Territories, and Interstate Commissions: Streams and Wadeable Rivers (EPA-822-R-02-048)"
Ease of Use and Interpretation
- The sampling frequency for trend assessment is less than for short-lived organisms
- Taxonomy of fishes is well established, enabling professional biologists the ability to reduce laboratory time by identifying many specimens in the field
- Distribution, life histories, and tolerances to environmental stresses of many species of North American fish are documented in the literature
(text from Simon and Lyons, Table 1, Application of the Index of Biotic Integrity to Evaluate Water Resource Integrity in Freshwater Ecosystems, Chapter 16, in Davis and Simon. 1995. Biological Assessment and Criteria - Tools for Water Resource Planning and Decision Making.)
Links
- Freshwater Fish Identification
- Office of Water’s Biological Assemblages and Protocols for Fish page
- Fish Health in the
Chesapeake Bay
- National Oceanic and Atmospheric Administration Fascinating
Facts about Fish
- Fishing
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