Nebraskaland

16 Nebraskaland • July 2021 IN THE FIELD By Eric Fowler STUDY TRACKING WALLEYE AND SAUGER Fishing hasn't been the same in Lewis and Clark Lake since historic flooding in 2011. Fisheries biologists hope studies of the movement of walleye and sauger now underway in the reservoir and Missouri River between Fort Randall and Gavins Point dams will help them better understand why. Researchers with South Dakota Game, Fish & Parks, the Nebraska Game and Parks Commission and the University of Nebraska-Lincoln School of Natural Resources implanted radio transmitters in 40 walleye and 40 sauger in the reach this spring and will track their movement past 16 receivers for the next few years. Biologists used nets, electrofishing and hook and line to catch a sampling of fish from different reaches of the river, reservoir and the delta at its upper end. Will Radigan, who is doing the field work as part of his graduate studies at SNR, said receivers spaced every 5 miles on alternating banks of the river and on both sides of the reservoir should pick up any fish that swims within a half mile. The first check of the data recorders in mid-May, about six weeks into the project, showed 60 percent of each species had already done so. "The majority of both have moved less than 5 miles, with the exception of one sauger that moved 40 miles and one walleye that moved a little over 55 miles," Radigan said. The latter was tagged below Fort Randall Dam and passed a receiver near Gavins Point Dam 24 days later. "My guess is that walleye is probably through the dam right now," he said. One walleye did pass through Gavins, detected on receivers tracking pallid sturgeon in the river below. The movement of fish through the dam, something biologists call entrainment, is part of the challenge of managing the fishery in the reservoir, which is more like a wide spot in the river. In a related study, Radigan is measuring the number of larval fish passing through the dam. The 2011 flood flushed many fish through the system, including emerald shiners, a primary forage base for the lake, and white bass. Jeff Schuckman, regional fisheries manager with Game and Parks, said those species haven't recovered, nor have walleye, despite stocking 87 million fry and 14 million fingerlings since 2014. The walleye catch rates in their fall gill net surveys on the reservoir remain well below pre-2011 levels, and angler success also has declined. Schuckman hopes the studies will help provide answers. "We're going to find out where the fish are moving to and from, and where they're living, and maybe get a chance to figure out what's attracting them to certain areas and then take a more in-depth look," he said. Each fish in the study also received a metal jaw tag stamped with a three-digit number, and anglers catching these fish are asked to call the conservation agency in their state to report the tag number. Radigan said in early June that one tagged sauger was harvested and two walleyes caught and released. Radio transmitters have been implanted in 40 sauger (pictured) and 40 walleye to study their movement in the Missouri River and Lewis and Clark Lake in northern Nebraska. The tagged fish are sporting jaw tags. ERIC FOWLER, NEBRASKALAND

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