Mimicking Nature: How water level management on a large reservoir affects walleye (Sander vitreus) spawning habitat (2015 MSc)

The Namakan Reservoir, located on the Minnesota-Ontario border, has been successively managed under two water-level management policies (‘rule curves’) in recent decades. To compare the effects of the rule curves on walleye spawning, I modeled wave energy, ice scour, and habitat availability at 44 spawning locations. Wave energy increased (18% for observed water levels, 6% for modeled water levels) and ice scour decreased 11% (both P < 0.01) over spawning habitat during the most recent rule curve. Observed water level data suggested available spawning habitat on Lake Kabetogama increased 95% (P < 0.01), but availability on Namakan and Sand Point Lakes was unaffected. However, when controlling for weather events, habitat availability increased significantly (Kabetogama = 179%, Namakan = 72%, Sand Point = 93%, P < 0.01) on all three lakes. These findings suggest that the most recent rule curve is likely to improve reproductive success for walleye in the reservoir.

Papenfuss JT, N Phelps, D Fulton, PA Venturelli (2015) Smartphones reveal angler behavior: a case-study of a popular mobile fishing application in Alberta, Canada. Fisheries 40:318-327

Papenfuss JT, TK Cross, PA Venturelli (2017) Comparing water-level policies in a boreal reservoir: how wave and ice energy can help maintain walleye spawning habitat. Lake and Reservoir Management 33:249-259