# G-control MP

`Gcontrol.Rd`

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

## Usage

```
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

## Value

An object of class `Rec-class`

with the `TAC`

slot populated with a numeric vector of length `reps`

## Details

The TAC is calculated as:
$$\textrm{TAC} = \textrm{SP} \left(1-gG\right)$$
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.

## Rendered Equations

See Online Documentation for correctly rendered equations

## References

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

## Examples

```
Gcontrol(1, Data=MSEtool::Atlantic_mackerel, plot=TRUE)
#> Error in if (all(round(TAC/mean(TAC, na.rm = TRUE), 1) == 1)) { points(max(years), mean(TAC, na.rm = TRUE), pch = 16, cex = 2, col = "blue") text(max(years), mean(TAC, na.rm = TRUE), "TAC", pos = 1, col = "blue")} else { boxplot(TAC, add = TRUE, at = max(years), col = "blue", width = 1, outline = TRUE, axes = FALSE) text(max(years), quantile(TAC, 0.95, na.rm = TRUE), "TAC", pos = 3, col = "blue")}: missing value where TRUE/FALSE needed
```