Updated 2023-11-07 16:38:56
Lake Michigan -> 6.0 Other Fish Species -> Species Evenness
Reporting Interval
2016 - 2021
Area
Southern Lake Michigan; Green Bay
Meeting Target?
Meets
Indicator Trend
No trend
Confidence?
Medium
6.1.2 Stable or increasing species evenness in the nearshore fish community
Species evenness scores above 0.7 indicate high evenness among species and those below 0.3 indicate increased dominance by one or a few species. Observed scores in southern Lake Michigan and Green Bay showed moderate evenness scores (Figure 1).
Figure 1. Species evenness at reference sites in Lake Michigan's main basin and Green Bay from 2016 - 2021.
Methodology
Annual sampling for the Green Bay FWCO Aquatic Invasive Species program covers multiple harbors of interest for early detection and monitoring of invasive fishes in Lake Michigan. Data from night electrofishing, graded-mesh gill net surveys, and fyke net sampling across multiple sites were used to document the community and detect rare and novel species, both native and non-native. From this dataset, species richness, Shannon diversity index and species evenness were calculated to describe the fish community in southern Lake Michigan and Green Bay. All species captured were included in these indices. The FCO specifically mentions native species for this metric, however many of the non-native species included contribute to the biological integrity of the fish community and are integral components of the modern Lake Michigan fish community (Eshenroder et al. 1995, Madenjian 2019).
Other Resources
- Eshenroder, R. L., M. E. Holey, T. K. Gorenflo, and R. D. Clark, Jr. 1995. Fish-community objectives for Lake Michigan. Great Lakes Fish. Comm. Spec. Pub. 95-3.
- Madenjian, C.P., [ED]. 2019. The state of Lake Michigan in 2016. Great Lakes Fish. Comm. Spec. Pub. 19-1.
Contributing Author(s)
- Cari-Ann Hayer - USFWS
- Nathan Barton - USFWS