Nebraskaland

52 Nebraskaland • August-September 2024 John Lorenzen, a student at South Dakota State University, was a technician on that survey. Later, for his master's thesis, he tested several fi sh ladder designs on perched culverts in the lab and on streams in eastern South Dakota and the Black Hills. What he found was a Denil-type ladder, with a series of fl at-topped baffl es that allow fi sh to ascend a short rise and then rest, was the most eff ective. In lab studies, all 14 species stocked in tanks were able to move up the ladder, and in the fi eld, 23 species did so. Wessel had followed his work with interest, and in 2020, with funding from the Game and Parks cool-water stream program, had a machine shop in Hartington build a ladder based on Lorenzen's design, and then installed it on a culvert on a branch of Bone Creek south of Ainsworth, simply as a proof of concept. "Until people can put eyes on it, it doesn't seem like it's a real option for them," Wessel said. In 2021, Wessel and fi sheries biologists identifi ed three stream and road crossings where the ladders could be installed on culverts with varying levels of drop: Bone Creek west of Ainsworth and Willow and Oak creeks north of Newport. That year, they used electrofi shing equipment to survey fi sh populations 150 meters above and below the culverts and then installed the fi sh ladders with traps at the top to see if any fi sh ascended them during a one-week period. Heavy rains caused the fi sh trap on Oak Creek to fail. Just two fi sh, including the western blacknose dace, were found in the trap on Willow Creek, but that site, with a 3-foot drop, would have been the most diffi cult for small fi sh to navigate. On Bone Creek, where the ladder was installed on a 1-foot drop, they found 93 fi sh. Most of those were white suckers and creek chubs, which have more jumping ability than other small minnows. "Did they jump up the 12-inch drop or did they go up the ladder? I don't know," said Joe Spooner, a fi sheries biologist. "Regardless, we still caught fi sh utilizing them. So that answered the question: Will they actually provide the opportunity? Yes." Realizing the site on Oak Creek could be problematic, another site was chosen on Sand Draw, a stream northwest of Ainsworth, with a similar 2-foot drop. Biologists sampled the streams in the spring, summer and fall in 2022 without fi sh ladders attached, and again in the spring of 2023 before attaching the ladders. Fish received a yellow mark on their side if they were captured above the culvert and red mark if caught below. Without fi sh ladders, 13 creek chubs and white suckers marked below the culverts were found above them. Before the ladders were removed in the fall of 2023, sampling found three marked fi sh that had moved upstream: Biologists Cassidy Wessel, Joe Spooner and Hunter Swanson sort, measure and record the number of fish sampled below a culvert fitted with a fish ladder on Bone Creek west of Ainsworth.

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