Analysis of the spawning stock–recruitment relationship of vendace (Coregonus albula (L.)) with evaluation of alternative models, additional variables, biases and errors

Abstract –  Spawning biomass and recruitment data for vendace from a central Finnish lake were analysed by fitting various recruitment models and comparing the fits statistically. The compensatory models of Ricker, Cushing and Beverton & Holt fitted the data better than the H ₀ hypothesis of constant proportionality, but model and parameter uncertainties were high. Additional variables were included in an attempt to reduce uncertainties. Heavy wind forcing during the first month after hatching of larvae reduced the recruitment success. For the Ricker and the Cushing models, recruitment seemed to be also negatively associated with the density of the previous year-class. The r ² increased considerably with inclusion of these additional variables, but the precision of model parameters remained low. Monte Carlo simulation of a vendace stock was applied to evaluate the interference of biases from the measurement error (ME) and time series error (TSE) in the analysis. Especially in the case of the Cushing model, compensatory density dependence can be overestimated severely. Increasing the number of observations decreases the biases in some cases. In view of potential biases and uncertainties, a precautionary management policy is recommended.