Vegetative substrates used by larval northern pike in Rainy and Kabetogama Lakes, Minnesota

Our objective was to identify characteristics of aquatic vegetative communities used as larval northern pike nursery habitat in Rainy and Kabetogama lakes, glacial shield reservoirs in northern Minnesota. Quatrefoil light traps fished at night were used to sample larval northern pike in 11 potential nursery areas. Larval northern pike were most commonly sampled among floatingleaf burreed Sparganium fluctuans, common burreed Sparganium eurycarpum, sedges Carex spp., hybrid cattail Typhapcpglauca and wild rice Zizania palustris. A negative binomial model of lighttrap catches using the presence/absence data for 2012 from all 11 bays included water elevation and the presence of cattail as significant variables. Ultimately, the species of vegetation may not be as important as the physical quality or form of the vegetation in supplying feeding and hiding cover. The aquatic plant species and structural forms encountered by larval northern pike suggest they use nearly any vegetated cover available in early spring. Waterlevel regulations that change availability of aquatic vegetation are likely to influence recruitment of northern pike to larger sizes.