Updated 2023-11-07 16:29:31
Lake Michigan -> 6.0 Other Fish Species -> Species Richness
Reporting Interval
2016 - 2021
Area
Southern Lake Michigan; Green Bay
Meeting Target?
Does Not Meet
Indicator Trend
Downward trend
Confidence?
Medium
6.1.1 Stable species richness in the nearshore fish community, including cyprinids, gars, bowfin, brook trout and sculpins
Species diversity across Lake Michigan can best be described through comprehensive surveys including multiple gears, habitat types, and locations. Early detection and monitoring work for aquatic invasive species across multiple nearshore sites around Lake Michigan provides a relative measure of trends in diversity and overall biological integrity and health.
Species richness, the total number of species within a given area, ranged from 56 to 67 at southern Lake Michigan main basin sites and 40-49 within Green Bay. Higher fish species richness in the main basin was likely due a wider range of habitat types (warm to cold water sites) represented across these sites compared to Green Bay alone. Some species that exemplified this difference such as bloater, golden redhorse, lake chub, lake trout, longnose sucker, redear sunfish, sand shiner, and silver redhorse were present only at main basin sites. Whereas species that often inhabit warmer, shallower areas such as alewife, bluegill, common carp, emerald shiner, gizzard shad, largemouth bass, rock bass, round goby, smallmouth bass, walleye, and yellow perch were present in Green Bay and at the more littoral main basin sites.
Figure 1. Species richness at reference sites within 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, evenness, and Shannon diversity index 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