Research Document 2012/075
Impact of stock-recruit and natural mortality process errors on MSY reference points
By N. Cadigan
The impact of stock-recruit and natural mortality process errors on MSY reference points (RPs) is investigated using simulations of stochastic projections. Process errors are the main source of variability in MSY projections. If the stochastic population projections achieve a stationary (i.e. steady-state) distribution then the mean of the stationary distribution may be used for RP’s for fisheries management, although the variance of the stationary distribution of population size should be accounted for in management decisions.
Two important characteristics of the process errors, namely their variance and auto-correlation, are varied to examine how these factors affect MSY RP’s. Results suggest that when the process error variance or auto-correlation is large then values for MSY RP’s may be lower. However, in this situation the stochastic projections may not lead to a stationary distribution depending on how the process errors are incorporated into the population dynamics model.
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