A Wisconsin DNR Fisheries Research crew will be on Elkhart Lake next week using vertical gill nets to sample for cisco as part of a statewide status survey. Cisco are a species of whitefish that live in the deep cold areas of about 175 Wisconsin lakes, including Elkhart Lake.
They are interested in Cisco because they play a key role in consuming zoo plankton, which are an important food for many small fish and which in turn can influence algae dynamics in lakes. Cisco are also a preferred prey for large walleye, musky, northern pike, and lake trout. They are delicious smoked and have small sport fisheries of their own in some lakes. Cisco require cold, well-oxygenated water, and are sensitive to poor water quality, so their presence indicates relatively good environmental conditions.
But we don’t know much about Cisco in most waters, including Elkhart Lake, which has never before been adequately surveyed for this species. In part this is because Cisco inhabit mid-water areas in the middle of deep lakes and are hard to collect with most of our standard sampling gear.
Vertical gill nets, which are rectangular panels of fine-mesh nets that extend from the surface to the bottom out in the middle of the lake, are specially designed to catch Cisco and work quite well for them while not catching many other fish. What people will see out on the lake will be a gang of floating rollers to which the vertical gill nets are attached. Each gang is about 60-ft long and consists of five 12-ft long X 1-ft diameter orange foam rollers. The rollers are anchored to the bottom and well-marked with flags and lights.