Evaluation of potential factors affecting the success of Cisco re-introduction and re-establishment in Lake Huron

Recent food web changes led to an opportunity to reintroduce (fingerling stocking) Cisco in central Lake Huron. We examined 9 factors affecting the ability of stocked Cisco fingerlings to survive, and reproduce and for their progeny to survive and reproduce. These values (obtained from the literature) were applied to a stochastic Leslie Matrix model and projected forward 30 years. The mean terminal eigenvalue (λ) of the final 10 years was used to indicate if the resulting wild population would continue to increase or decrease and thresholds for each variable. Recovery success was sensitive to survival rates especially in early life stages. Numbers stocked and the rate of homing by hatchery fish only affected the rate of recovery. Adult survival, if adjusted up, helped compensate for many of the earlier life stages lower survival rates. Simulations indicated the likelihood of successful establishment of ongoing natural reproduction if periodicity of boom years of reproduction were at least once every 5 years on average, but higher adult survival rates can relax this requirement allowing for an expanding population at less frequent periodicities.