Index Target based on natural mortality rate

An index target MP where the TAC is modified according to current index levels (mean index over last number of years determined by natural mortality (M)) relative to a target level.

Usage

ITM(x, Data, reps = 100, plot = FALSE)

Arguments

x: A position in the data object
Data: A data object
reps: The number of stochastic samples of the MP recommendation(s)
plot: Logical. Show the plot?

Value

An object of class Rec-class with the TAC slot populated with a numeric vector of length reps

Details

The TAC is caluclated as: $$\textrm{TAC}_y = \textrm{TAC}_{y-1} \delta I$$ where $\delta I$ is the ratio of the mean index over $4\frac{1}{M}^{1/4}$ years to the reference index (Data@Iref).

The maximum fractional change in TAC is determined by $mc$, defined as $mc = \textrm{max}\left(\frac{5 + 25M}{100}, 0.2\right)$

Required Data

See Data-class for information on the Data object

ITM: Ind, Iref, MPrec, Mort

Rendered Equations

See Online Documentation for correctly rendered equations

Author

T. Carruthers

Examples

ITM(1, Data=MSEtool::SimulatedData, plot=TRUE)

#> TAC (median) 
#>     1950.633