Set up parameters for a model with allometric encounter and mortality rates

This function sets up a model with allometric encounter and mortality rates for each species and no interaction between the species or with the resource. The initial abundances are set to the steady-state abundances with the total biomass for each species matched to observations. The metabolic respiration rate, the feeding level and the reproduction level are set to zero.

Usage

newAllometricParams(species_params, no_w = 200)

Arguments

species_params

A data frame with species parameters

no_w

The number of weight bins to use in the model

Value

A MizerParams object

Details

If the exponent n of the power-law encounter rate is not provided as a species parameter, it is set to 0.7. The exponent d of the power-law mortality rate is always imposed as n - 1, regardless of any supplied value.

If the species parameter alpha, which gives the proportion of the consumption that is assimilated, is not provided, it is set to 0.8, the default value used by Ecopath.

The coefficient of the power-law encounter rate for each species is chosen so that the species grows to maturity size by its maturity age. The coefficient of the power-law mortality rate is computed from the growth rate and is chosen so that the juvenile biomass density has a slope of -0.2.

The species uses matchGrowth() to adjust the encounter rate coefficient to produce the desired growth rate. It uses matchBiomasses() to match the biomass to the observations and steadySingleSpecies() to set the model to steady state.

Because the model does not make use of the resource spectrum, the resource dynamics is switched off.