Factors Affecting Recruitment of Age‐0 Muskellunge in Escanaba Lake, Wisconsin, 1987–2006

Abstract

AbstractWe modeled variation in recruitment (R) of age‐0 muskellunge Esox masquinongy to identify factors influencing their abundance in Escanaba Lake, Wisconsin. Muskellunge R declined over the study period and ranged from 0.00 to 1.85 age‐0 fish/km of shoreline (mean = 0.42 age‐0 fish/km of shoreline). A Ricker stock–recruitment model determined that the following factors explained 88% of the variation in annual R of age‐0 muskellunge between 1987 and 2006: abundance and age structure of the adult muskellunge population, abundance of bluntnose minnow Pimephales notatus, abundance of age‐3 and older (age‐3+) walleyes Sander vitreus, abundance of age‐0 white suckers Catostomus commersonii, and coefficient of variation (CV) of May water temperatures. Abundance of adult muskellunge (≥76.2 cm total length) accounted for only 1% of the variation in R and showed no significant relationship with R. Abundance of bluntnose minnow improved the model fit to 40% of the variation in R and indicated that higher R was achieved with greater numbers of bluntnose minnow. The average age of adult muskellunge further improved the model fit to 59% of the variation in R, suggesting that R increased when more young adults were present in the population. The abundance of age‐3+ walleyes enhanced the model fit to 69% of the variation in R and indicated that greater R occurred with high numbers of walleyes. The abundance of age‐0 white suckers improved the model to explain 77% of the variation in R and indicated that more recruits occurred when numbers of age‐0 white suckers were low. Finally, the CV of May water temperatures further improved the model to explain 88% of the variation in R and signified that lower variability in May water temperatures was beneficial to recruitment success. We interpret the model results to mean that muskellunge R in Escanaba Lake is regulated by the reproductive potential of the adult muskellunge population, forage availability, variation in May water temperatures, and other community dynamics.