Fish Species in the Chicago Area Waterway System
The MWRD aquatic ecology team tracks the density and diversity of fish populations in the area waterways. We use boat-mounted and backpack electrofishers, and seines to collect fish at sampling locations throughout the region. The fish are weighed, measured, identified and returned to the river.
Since monitoring began in the early 1970s, we have seen dramatic improvements in species diversity, from just ten species in 1974 to 77 today. The overall fish population and size of individual fish have also increased as water quality has improved. Our studies with partners at the Shedd Aquarium have also shown that native species have increased while the number of invasive species has declined.
Fish Species Collected by the MWRD in the Chicago Area Waterway System since 1974
In 2022 we collected this largemouth bass weighing over four pounds - the largest individual of this species we have collected since sampling began in 1974.