Estimating local settler–recruit relationship parameters for complex spatially explicit models

Spatially explicit models are needed to thoroughly evaluate the potential effectiveness of marine protected areas in particular locations. These models have traditionally parameterized a spatially non-varying settler–recruit relationship (SRR), which is often the large-scale, non-spatial stock–recruitment or egg–recruit relationship used for stock assessments. A recent study demonstrated that the initial slope of local SRRs should be adjusted so as to correctly estimate population persistence, and proposed an analytical methodology to carry out the adjustment. This methodology cannot be used to evaluate small-scale SRRs for more complex spatially explicit models, in particular when adults of the study population are mobile beyond simple home range movements. Here we propose a numerical methodology for estimating the parameters of local SRRs for complex spatially and seasonally explicit population models, from parameters of a large-scale, non-spatial SRR. The consideration of spatial and seasonal patterns of fishing mortality rates, reproduction and larval dispersal results in discrepancies between spatial monthly models and equivalent non-spatial annual models in terms of global spawning stock biomass. The adjustment of the initial slope of small-scale SRRs is necessary so as not to underestimate population persistence, and also reduces discrepancies between spatially and seasonally explicit models and their non-spatial annual counterparts.

► We develop a methodology for estimating local settler–recruit relationship parameters for complex spatially and seasonally explicit models.
► The adjustment of the initial slope of local settler–recruit relationships is necessary to correctly estimate population persistence.
► This adjustment also reduces discrepancies between spatially and seasonally explicit models and their non-spatial annual counterparts.