by Ken Leinbach
A motor boat… at least that’s what it sounds like… under the Locust Street Bridge? How did it get there? Is it legal? Who’s in it? These were the questions going through my mind as I led a small group in Riverside Park. I ran ahead to a view point and sure enough, there was a bass boat trolling along the Gordon Park bank. Two people were standing in the bow with a third controlling the motor. What the heck were they doing? The front of the boat had what looked like a large basketball hoop attached to a long pole extending eight feet over the bow. The “basket” was comprised of -inch steel cables dangling in the water. The crew in front was feverishly scooping up what appeared to be dead fish and dumping them in a large metal tank (perhaps an old cattle watering trough) situated in the middle of the boat. I finally figured it out. This was that fish shocking sampling method that I had heard about. Upon return to the Ecology Center, there was a cell phone message from our good friend Will Wawrzyn, Fisheries Biologist from the DNR. “Ken, I saw you on the river… if you get a group together, come on down and we’ll sort through our sample catch in Riverside Park.” What a treat! Our staff and volunteers, joined by a couple new interns and a passing dog walker, headed down to the river for a spontaneous lesson. It turns out that the “basket ball hoop” in front was in fact an electric anode. The metal boat bottom acted as the cathode. When charged with a generator the boat makes an underwater electric wedge. Any fish swimming within the wedge gets stunned and floats to the surface. Amazingly, almost all the fish survive the ordeal unharmed. This is how the DNR determines the health of the river. We watched as every fish was weighed, measured, scrutinized for disease or defect, and in some cases tagged. Eventually the fish were re-released to the waters. We were awed and amazed by the quantity, beauty, and variety of fish in our River! Walleye to drool over (11 in all), 20 rock bass, a log perch and 75(!) small mouth bass. One, a 20-inch greater red horse, is a threatened species for the Milwaukee River… a beautiful fish I had never seen before. In all, counting the less desirable (non native) carp and chum, there were 19 species and well over 250 fish in total — this representing a very small sampling of fish swimming in our sediment filled waters. Will told me later that before the North Avenue dam was removed they’d be lucky to get a fish and that only a few species (like the carp, bull head, and white sucker) could survive. Today he estimates approximately 30 species are swimming in our local waters with over 45 species in the entire river. These fish are there every day and night, neighbors of ours, though largely invisible. While there is skepticism about the health of the river, the good news is that there is abundant life beneath the surface. Every Wednesday morning at 9:30 Ken Leinbach, Executive Director of the Urban Ecology Center, leads a nature walk through Riverside Park and down the Milwaukee River. Join him for a first hand experience with the river.