Index Slope Tracking MP

A management procedure that incrementally adjusts the TAC to maintain a constant CPUE or relative abundance index.

Islope1(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.2)

Islope2(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.3)

Islope3(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.4, xx = 0.4)

Islope4(x, Data, reps = 100, plot = FALSE, yrsmth = 5, lambda = 0.2, xx = 0.4)

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

Years over which to calculate index
lambda

A gain parameter controlling the speed in update in TAC.
xx

Parameter controlling the fraction of mean catch to start using in first year

Value

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

Details

The TAC is calculated as: $$\textrm{TAC} = \textrm{TAC}^* \left(1+\lambda I \right)$$ where \(\textrm{TAC}^*\) is \(1-xx\) multiplied by the mean catch from the past yrsmth years for the first year and catch from the previous year in projection years, \(\lambda\) is a gain parameter, and \(I\) is the slope of log index over the past yrsmth years.

Functions

  • Islope1: The least biologically precautionary of the Islope methods

  • Islope2: More biologically precautionary. Reference TAC is 0.7 average catch

  • Islope3: More biologically precautionary. Reference TAC is 0.6 average catch

  • Islope4: The most biologically precautionary of the Islope methods. Reference TAC is 0.6 average catch and gain parameter is 0.2

Required Data

See Data for information on the Data object

Islope1: Cat, Ind, LHYear, 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.

Geromont, H.F., Butterworth, D.S. 2014. Generic management procedures for data-poor fisheries; forecasting with few data. ICES J. Mar. Sci. doi:10.1093/icesjms/fst232

See also

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

Examples

Islope1(1, DLMtool::SimulatedData, plot=TRUE)
#> TAC (median) 
#>     1117.679 
Islope2(1, DLMtool::SimulatedData, plot=TRUE)
#> TAC (median) 
#>     1120.563 
Islope3(1, DLMtool::SimulatedData, plot=TRUE)
#> TAC (median) 
#>     1126.593 
Islope4(1, DLMtool::SimulatedData, plot=TRUE)
#> TAC (median) 
#>     1117.031