Ozaukee County Planning and Parks Department (Department) staff, with the help of volunteers, conducts electrofishing fisheries monitoring on an annual basis, as site conditions and grant funding allow. These surveys typically occur in the late spring and summer and consist of electrofishing by boat mounted, backpack or tow-behind barge units. Tow-behind barges and boat mounted electrofishing units are used to conduct fish surveys on the Milwaukee River, while backpack electrofishing is used to conduct fish surveys on the smaller tributaries.
Electrofishing surveys collect information about existing fish communities and potential native indicator fish species. The Department also performs mark-recapture electrofishing surveys at all large-scale fish passage impediment removal or remediation projects, which is used to demonstrate fish passage following construction and restoration activities. Sampling sites include 100-meter long reaches up and downstream of each impediment (project reach). Block nets are installed and maintained at the upstream and downstream end of each site prior to construction activities to remove fish from the project reach during construction, and to complete pre-construction sampling and marking. Prior to construction activities, fish are captured upstream and downstream of the impediment and clipped on the upper or lower caudal fin, respectively. All fish are then released downstream of the downstream block net. Removal of fish from the immediate construction area decreases fish mortality and prevents fish from becoming trapped in the dewatered construction area. Following construction activities, the downstream block net is removed and after a period of 24 hours, each project reach is re-sampled to determine if marked fish have moved upstream of the former impediment to demonstrate successful fish passage. Data from all electrofishing surveys is maintained by the Department and routinely provided to the Wisconsin Department of Natural Resources for inclusion in the Surface Water Integrated Monitoring System (SWIMS) database.
Fish are tagged and clipped to help track seasonal spawning runs and other movement patterns throughout the Milwaukee River and tributary streams. 500 fish have been tagged or marked during fish surveys near the Mequon-Thiensville Fishway. Recaptures of tagged or marked fish are documented in future surveys, reported by local anglers or detected by the underwater camera and Passive Integrated Transponder (PIT) tag readers in the fishway exit. View more information on the camera and tag readers.
Browse through photos that display some typical fish monitoring activities and techniques, including tagging and clipping. The Fish Passage Program is always on the lookout for additional volunteers to assist with fish surveys in Ozaukee County contact the Fish Passage Program via email.