Match yields to observations

The function adjusts the abundances of the species in the model so that their yearly yields under the given fishing mortalities match with observations.

Usage

matchYields(params, species = NULL)

Arguments

params

A MizerParams object

species

The species to be affected. Optional. By default all observed yields will be matched. A vector of species names, or a numeric vector with the species indices, or a logical vector indicating for each species whether it is to be affected (TRUE) or not.

Value

A MizerParams object

Details

The function works by multiplying for each species the abundance density at all sizes by the same factor. This will of course not give a steady state solution, even if the initial abundance densities were at steady state. So after using this function you may want to use steady() to run the model to steady state, after which of course the yields will no longer match exactly. You could then iterate this process. This is described in the blog post at https://bit.ly/2YqXESV.

Before you can use this function you will need to have added a yield_observed column to your model which gives the observed yields in grams per year. For species for which you have no observed biomass, you should set the value in the yield_observed column to 0 or NA.

Examples

params <- NS_params
species_params(params)$yield_observed <- 
    c(0.8, 61, 12, 35, 1.6, 20, 10, 7.6, 135, 60, 30, 78)
gear_params(params)$catchability <-
    c(1.3, 0.065, 0.31, 0.18, 0.98, 0.24, 0.37, 0.46, 0.18, 0.30, 0.27, 0.39)
params <- calibrateYield(params)
params <- matchYields(params)
#> The following species are not being fished in your model and their abundances will not be changed: Sprat, Sandeel, N.pout.
plotYieldObservedVsModel(params)
#> The following species are not being fished in your model and will not be included in the plot: Sprat, Sandeel, N.pout.