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Surplus Production Model Settings from the Operating Model

Source: R/define_cmps.R
SPSettings.Rd

Derives the fixed parameters and informative priors of the surplus production model used by MSEtool::SurplusProduction() from the operating model, so that the assessment model in the MP matches the productivity and initial depletion of the base case OM.

Usage

SPSettings(Hist, MinCV = c(FMSY = 0.3, MSY = 0.4))

Arguments

Hist

A hist object (the base case OM).

MinCV

Named numeric vector. Minimum CV of the priors on FMSY and MSY. Default c(FMSY = 0.3, MSY = 0.4).

Value

A list with Priors (a list of c(median, CV) for FMSY and MSY, see MSEtool::FitSP()), Shape, Depletion, and OM (a data.frame of the per-simulation OM values).

Details

The surplus production model has a single biomass pool, so the OM quantities are calculated for the total biomass of both sexes:

  • MSY: equilibrium removals at MSY (MSYLandings + MSYDiscards).

  • FMSY: the harvest rate at MSY, MSY / BMSY, where BMSY is the total equilibrium biomass at MSY. This is the FMSY of the surplus production model, not the apical fishing mortality of the OM.

  • Shape: the Pella-Tomlinson shape parameter n with n^(1/(1-n)) = BMSY/B0, the median over simulations.

  • Depletion: total biomass relative to unfished at the start of the first historical year (B/B0), the median over simulations.

The priors are lognormal, with median equal to the median over simulations and CV equal to the CV of the OM values over simulations or MinCV, whichever is larger.