Fish Index of Biotic Integrity (FIBI)

The FIBI is a stream assessment tool that evaluates the biological integrity at a site based on the characteristics of the fish that are found there. The MBSS computes the FIBI as the average of individual metric scores, based on comparisons to reference sites within each geographic region. An IBI score of 3 represents the threshold of reference condition; values less than 3 (Poor or Very Poor) represent sites that are degraded. Values greater than or equal to 3 (Fair or Good) indicate that most attributes of the community are within the range of those at reference sites and therefore not degraded.
Details on the development and application of MBSS IBIs are in this document.

1 - 2Strong deviation from reference conditions, with most aspects of biological integrity not resembling the qualities of these minimally impacted streams, indicating severe degradation.
2 - 3Significant deviation from reference conditions, with many aspects of biological integrity not resembling the qualities of these minimally impacted streams, indicating some degradation
3 - 4Comparable to reference conditions, but some aspects of biological integrity may not resemble the qualities of these minimally impacted streams. Fall within the lower portion of the range of reference sites (10th to 50th percentile).
4 - 5Comparable to reference streams considered to be minimally impacted. Fall within the upper 50% of reference site conditions.

For more comprehensive and detailed information, download the Guide to using MBSS Data (536 KB).