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NGPC summarizes Lewis and Clark Lake research: flows, entrainment and paddlefish permit trends
Summary
Phil Shabalala, fisheries biologist with NGPC's Norfolk office, summarized Lewis and Clark Lake research showing recent improved catch rates, a strong sensitivity of the fishery to river flow, and measured entrainment and movement of adult walleye and sauger.
Phil Shabalala, fisheries biologist with the Nebraska Game and Parks Commission's Norfolk office, summarized a recent Lewis and Clark Lake research project and explained how river flows and entrainment affect the reservoir's fishery.
Shabalala described multi-year sampling showing improved combined walleye and sauger catch rates in recent years and emphasized the system's sensitivity to flow. He said mean flows above roughly "25,000 CFS" correspond with lower walleye catch rates in Lewis and Clark; the lake's relatively rapid exchange rate means inflowing water replaces reservoir volume much faster than at other mainstem reservoirs, making the fishery more flow-dependent.
Research details
- Larval entrainment and adult movement: A University of Nebraska–Lincoln researcher, Will Radagon, assessed larval entrainment through Fort Randall and Gavins Point dams and tracked adults with surgically implanted acoustic transmitters. The study detected movement across zones and documented both "homebody" fish and long-distance movers; some individuals migrated between Fort Randall tailwaters and Lewis and Clark Lake.
- Entrainment losses: Shabalala said the study's entrainment estimate for adults in the sampled tagged fish was small but measurable, about "2 to 3 percent" in the sample; he cautioned that higher-flow years would likely increase entrainment losses.
- Telemetry findings: Tagged fish showed a mix of movement patterns: some sauger tended to be localized while other sauger and many walleye moved longer distances; both males and females contributed to the moving fraction. Shabalala noted that adult entrainment and summertime mortality were among the highest sources of loss observed.
Paddlefish permits and seasons
Shabalala also summarized paddlefish permit allocation and success differences between archery and snagging seasons. He said the archery season issues: the commission distributes about "275" archery permits; increased interest has made the interval between successful draws for individual applicants longer (staff estimated an applicant could expect several years between draws if application pressure remains high). By contrast, the snagging season (October) issues about "1,600" permits and uses a protected slot (35–45 inches measured from front of eye to fork of tail) that must be released.
Quotes from the presentation
- On flows and fish production: "It's like that 25,000 CFS is kind of a breaking point, if you will," Shabalala said, summarizing the relationship between flow and walleye catch rates.
- On entrainment in the study: "In a higher flow year, we'd probably we expect that to be a little bit higher," he said when discussing entrainment percentages.
Ending: Shabalala directed listeners to the NGPC website for the full report and said the telemetry and entrainment results will inform continued monitoring; he warned that flow management outside NGPC's control remains a key driver of reservoir production.
