Estimating Uncertainty in the Stock-Recruitment Relationship for St. Marys River Sea Lampreys

Abstract

For successful control of the St. Marys River sea lamprey ( Petromyzon marinus) population, one critical uncertainty that needs to be characterized is uncertainty in the stock-recruitment relationship. A statistically-based, age-structured population model was developed to estimate the parameters of a Ricker stock-recruitment relationship for St. Marys River sea lampreys and the associated uncertainty in these parameters. This analysis indicated considerable stock-independent variability in recruitment across a range of stock sizes, potentially limiting the effectiveness of control options that reduce the spawning population in comparison to those that reduce the larval population. Point estimates of the stock-recruitment parameters suggest moderate compensation, but the uncertainty in these point estimates is large, spanning a range from negligible to high compensation. By characterizing these uncertainties and incorporating the results into a decision analytic framework, it is then possible to evaluate the effects of compensation and stock-recruitment uncertainty on management options available for St. Marys River sea lamprey control.