We assessed the length structure of walleyeStizostedion vitreumpopulations over time in five high-elevation (> 1340 m above mean sea level) reservoirs in Wyoming using relative stock density (RSD). Four populations showed moderate to large fluctuations in RSD values across years, while one population was relatively stable. Fluctuations in RSD values were associated with variability in annual recruitment. Incremental RSD values allowed identification and tracking of weak year classes through time. Because of inconsistent annual recruitment, the utility of RSD for assessing the rates of recruitment, growth, and mortality of walleye populations in large reservoirs is limited.