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AUTHORS: Nathan Johnston, Dale Shank, Chris Kemp, and Jeffrey Miner, Aquatic Ecology & Fisheries Lab, Bowling Green State University
ABSTRACT: The Maumee River in Lake Erie is an important spawning ground for Walleye Sander vitreus with the first upstream spawning habitat occurring approximate 20 km from Lake Erie. Larvae hatching from the spawning grounds must traverse this habitat that includes about 10 km of dredged shipping channel (8-10 m deep). Trying to quantify abundance and mortality of these larvae as they move downstream includes understanding of temporal pattern of dispersal. Most often, quantifying this distribution and population abundance involves weekly sampling and then interpolation of densities and flow conditions. However, the periodicity of the dispersal is not well known. We sampled daily just downstream of the spawning grounds for three years to determine the daily variability of this distribution. We found that 37-69% of larval walleye dispersed from spawning grounds in just three days each spring. Often abundance was as much as 10 times lower the day before or after peak abundance. For accurate abundance estimates of larval Walleye dispersing from spawning grounds and to project mortality as larvae pass downstream, much more intense sampling is required to accurately estimate life history dynamics.
