Juvenile muskellunge escapement and movement in an aging Wisconsin reservoir.

Abstract

Muskellunge (Esox masquinongy) fisheries are popular throughout the Midwest, including Wisconsin where stocking efforts to provide angling opportunities are common. Since 2006, over 20,000 Muskellunge have been stocked into Neshonoc Lake, an impoundment of the La Crosse River. Relatively few have been recaptured in the reservoir during standardized surveys and individuals are thought to escape downstream to the river. My objectives were to: (1) delineate the reservoir bathymetry using side scan sonar, (2) describe movement behaviors and spatial patterns of stocked Muskellunge in the reservoir, and (3) quantify escapement for one year after stocking. Thirty juvenile Muskellunge were implanted with acoustic tags (Innovasea, V9-1x) to monitor their movements using four stationary receivers and were regularly located using a directional hydrophone during three movement periods (i.e., post-stocking, fall, spring). More than 50% of the lake was < 1 m deep with a max of 4 m, a result of recent dredging efforts and there was little substrate variability or cover structure. Muskellunge were most often detected near shore, in relatively shallow water (1-2 m), and moved greater distances in fall than spring. No juveniles escaped during the lifespan of the tags, suggesting that escapement does not occur at this life stage.