SPmod: Surplus production based catch-limit modifier

In DLMtool: Data-Limited Methods Toolkit

Surplus production based catch-limit modifier

Description

An MP that makes incremental adjustments to TAC recommendations based on the apparent trend in surplus production. Based on the theory of Mark Maunder (IATTC)

Usage

SPmod(x, Data, reps = 100, plot = FALSE, alp = c(0.8, 1.2), bet = c(0.8, 1.2))

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?
alp	Condition for modifying the TAC (bounds on change in abundance)
bet	Limits for how much the TAC can change among years

Details

Note that this isn't exactly what Mark has previously suggested and is stochastic in this implementation.

The TAC is calculated as:

\textrm{TAC}_y = ≤ft\{\begin{array}{ll} C_{y-1} \textrm{bet}_1 & \textrm{if } r < α_1 \\ C_{y-1} & \textrm{if } α_1 < r < α_2 \\ \textrm{bet}_2 (b_2 - b_1 + C_{y-2} ) & \textrm{if } r > α_2 \\ \end{array}\right.

where \textrm{bet}_1 and \textrm{bet}_2 are elements in bet, r is the ratio of the index in the most recent two years, C_{y-1} is catch in the previous year, b_1 and b_2 are ratio of index in y-2 and y-1 over the estimate of catchability ≤ft(\frac{I}{A}\right), and α_1, α_2, and α_3 are specified in argument alp.

Value

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

A numeric vector of TAC recommendations

Required Data

See Data-class for information on the Data object

SPmod: Cat, Ind

Rendered Equations

See Online Documentation for correctly rendered equations

Author(s)

T. Carruthers

References

http://www.iattc.org/Meetings/Meetings2014/MAYSAC/PDFs/SAC-05-10b-Management-Strategy-Evaluation.pdf

See Also

Other Surplus production MPs: Fadapt(), Rcontrol(), SPMSY(), SPSRA(), SPslope()

Examples

SPmod(1, Data=MSEtool::Atlantic_mackerel, plot=TRUE)

DLMtool documentation built on June 20, 2022, 5:14 p.m.