G-control MP

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

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 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.

Required Data

See Data for information on the Data object

Gcontrol: Abun, Cat, Ind, Year

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.

See also

Other Index methods: GB_slope(), GB_target(), ICI(), Iratio(), Islope1(), Itarget1_MPA(), Itarget1(), ItargetE1()

Examples

Gcontrol(1, Data=DLMtool::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