# Gcontrol: G-control MP In DLMtool: Data-Limited Methods Toolkit

## Description

A harvest control rule proposed by Carl Walters that uses trajectory in inferred surplus production to make upward/downward adjustments to TAC recommendations

## Usage

 1 2 3 4 5 6 7 8 9 Gcontrol( x, Data, reps = 100, plot = FALSE, yrsmth = 10, gg = 2, glim = c(0.5, 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? yrsmth The number of years over which to smooth catch and biomass data gg A gain parameter glim A constraint limiting the maximum level of change in quota recommendations

## Details

The TAC is calculated as:

\textrm{TAC} = \textrm{SP} ≤ft(1-gG\right)

where \textrm{SP} is the predicted surplus production for the next year, g is a gain parameter, and G is the slope of surplus production as a function of biomass over the last yrsmth years.

The change in TAC is bounded by the glim argument, which by default does not allow the TAC to decrease by more than half or increase more than twice the last annual catch.

## Value

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

## Required Data

See Data for information on the Data object

Gcontrol: Abun, Cat, Ind, Year

## Rendered Equations

See Online Documentation for correctly rendered equations

## Author(s)

C. Walters and T. Carruthers

## References

Carruthers et al. 2015. Performance evaluation of simple management procedures. ICES J. Mar Sci. 73, 464-482.

Other Index methods: GB_slope(), GB_target(), ICI(), Iratio(), Islope1(), Itarget1_MPA(), Itarget1(), ItargetE1()
 1 Gcontrol(1, Data=DLMtool::Atlantic_mackerel, plot=TRUE)