Modeling the Influence of Parr Predation by Walleyes and Brown Trout on the Long-Term Population Dynamics of Chinook Salmon in Lake Michigan: A Stage Matrix Approach

Abstract

Abstract Predation events during ontogeny may have long-term consequences for fish population abundance and variability. We used a stage-based matrix model to evaluate Walleye Sander vitreus and Brown Trout Salmo trutta predation on Chinook Salmon Oncorhynchus tshawytscha parr of the Muskegon River stock and the relative influence of parr predation on the long-term population dynamics and recruitment of Chinook Salmon in Lake Michigan. The model predicted the number of Chinook Salmon individuals in each stage (fry, smolts, and lake age 0 [recruits] through lake age 4) and forecasted population trajectories based on demographic data (e.g., survival, growth, and fecundity). The relative influence of parr predation was compared with influences of environmental stochasticity in the egg stage and Alewife Alosa pseudoharengus abundance (prey for lake-stage salmon) on Chinook Salmon fecundity, recruitment, and population growth. To simulate environmental stochasticity and the influence of Alewife abundance, we v...