1. IBI’s: How It’s Done

2. Components of IBI Development

3. (1) Regional Fish Fauna
The physico-chemical environment determines community structure and composition
A fish’s habitat requirements and tolerances speaks toward the local environmental conditions
Distribution and life history very prominent in literature

4. (1) Evaluation of Metric Suitability
Scoring range
Broad range desirable
Variability
Signal / Noise test
Responsiveness
Sensitivity to physical and chemical variables
Redundancy
Attempt to reduce among metrics
(Hughes et al. 1998)

5. (1) Reference Condition
Least impacted sites within the area of study
May be stratified by watershed, ecoregion, etc.
Typically use a quantile approach where the highest or lowest* 5-10% set the baseline conditions
*Highest or lowest depends whether the metric is positive or negative scoring

7. (2) Sampling Approaches / Design
Probabilistic
Targeted
Hybrid Approaches

8. Site Selection
Representative reach with at least 1 riffle-pool sequence
Reach length based on mean stream width with a maximum and minimum length

9. Sampling the Fish Community
Backpack electrofishing with a seine net

10. Identification and Tabulation
Fish are generally not weighed and measured but identified to species
Fish often examined for DELT anomalies (deformities, eroded fins, lesions, and tumors)

12. IBI Metrics
Individuals provide little information but proportions of the community are very telling
Scaling allows for comparisons across a variety of sizes of waterbodies

13. Calculation of IBI score
Raw metrics are divided by scores from reference sites
Scored metrics are summed and total is corrected for a 100 point scale

14. Assignment and Interpretation
Total score is assigned to some predetermined integrity class
Example: = Good
= Fair
< = Poor
Interpretation is based on assignment and goals and objectives of assessment