Fish populations in Lake Mendota, Lake Monona, Lake Waubesa and Lake Kegonsa were sampled to identify species within various nearshore habitats and to assess potential factors that may affect species distributions. Lake Mendota and Lake Monona were sampled at 20 sites each in 2017 using wadable DC electroshocking gear and targeting smaller-bodied fish. Lake Kegonsa was sampled at 18 sites in 2019 and Lake Waubesa at 18 sites in 2020 using the same electroshocking gear. The surveys were also useful for reviewing the status of environmentally sensitive and uncommon species that were previously found in the lakes. With the exception of the tadpole madtom (Noturus gyrinus), the status of seven other small littoral zone species that had disappeared from the Yahara Chain of Lakes remain unchanged. None were found. The tadpole madtom was recently discovered at one site in Cherokee Marsh and at two sites in Lake Kegonsa. Other small nongame fish species, including the Iowa darter (Etheostoma exile), displayed a clear preference for cobble-gravel shoals. However, this habitat type is now uncommon in the lakes as most shorelines are armored with riprap and to a lesser extent seawall. Our data suggests that in addition to widely accepted environmental factors such as eutrophication, invasive Eurasian watermilfoil, and numerous piers, these small nongame fish species are also susceptible to sustained high water levels combined with shoreline armoring. The pattern is similar for all four lakes. Most littoral zones that are lined with boulder riprap and are primarily inhabited by green sunfish (Lepomis cyanellus), yellow bullhead (Ameiurus natalis), juvenile smallmouth bass (Micropterus dolomieu), bluegill (Lepomis macrochirus) and juvenile largemouth bass (Micropterus salmoides).

Image used for the 2020 Story Map. Project associated with image is Surveys of Lake Waubesa Nearshore Fish Populations.

Grant SPL39719 awarded