Northern Pike Young-of-the-Year Habitat Characteristics in Water-Level Regulated Border Waters of Minnesota and Ontario

Rule curves have been implemented by the U.S.-Canada International Joint Commission (IJC) to regulate water levels in Minnesota-Ontario border waters.  The 2000 rule curves in Rainy Lake and Namakan Reservoir border waters should expand the range of elevations covered by aquatic vegetation available as northern pike nursery habitat as a result of an earlier spring rise.  The objective of this study was to identify temperature, depth, and aquatic macrophyte species characteristics associated with highly productive northern pike young-of-the-year (YOY) habitat resulting from expanded areas of aquatic vegetation.  Trap-net samples for YOY northern pike were collected at 155 locations in 2012 and 159 locations in 2013 in Rainy Lake and Namakan Reservoir.  Aquatic macrophyte surveys were conducted at each trap-net location that included presence, percent cover, and stem density data.  Our study fit negative binomial poisson, zero-inflated poisson, and zero-inflated negative binomial models using the FMM procedure for finite mixture models to determine significant variables related to YOY northern pike count.  Best fit models with the lowest AIC criteria identified temperature, count of submergent plant species, presence of Utricularia macrorhiza, presence of Vallisneria americana, and presence of Elodea canadensis as significant variables positively related to northern pike YOY count.