Incremental Index Target MP

A management procedure that incrementally adjusts the TAC (starting from reference level that is a fraction of mean recent catches) to reach a target CPUE / relative abundance index

Four index/CPUE target MPs proposed by Geromont and Butterworth 2014. Tested by Carruthers et al. 2015.

Itarget1(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, Imulti = 1.5)

Itarget2(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, Imulti = 2)

Itarget3(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0, Imulti = 2.5)

Itarget4(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xx = 0.3, Imulti = 2.5)

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 the average index is calculated.
xx

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

Parameter controlling how much larger target CPUE / index is compared with recent levels.

Value

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

Details

The TAC is calculated as: If \(I_\textrm{recent} \geq I_0\): $$\textrm{TAC}= 0.5 \textrm{TAC}^* \left[1+\left(\frac{I_\textrm{recent} - I_0}{I_\textrm{target} - I_0}\right)\right]$$

else: $$\textrm{TAC}= 0.5 \textrm{TAC}^* \left[\frac{I_\textrm{recent}}{I_0}^2\right]$$

where \(I_0\) is \(0.8 I_{\textrm{ave}}\) (the average index over the 2 x yrsmth years prior to the projection period), \(I_\textrm{recent}\) is the average index over the past yrsmth years, and \(I_\textrm{target}\) is Imulti times \(I_{\textrm{ave}}\), and \(\textrm{TAC}^*\) is: $$(1-x)C$$ where \(x\) is argument xx and C is the average catch over the last 5 years of the historical period.

Functions

  • Itarget1: The less precautionary TAC-based MP

  • Itarget2: Increasing biologically precautionary TAC-based MP

  • Itarget3: Increasing biologically precautionary TAC-based MP

  • Itarget4: The most biologically precautionary TAC-based MP

Required Data

See Data for information on the Data object

Itarget1: 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. 72, 251-261. doi:10.1093/icesjms/fst232

See also

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

Examples

Itarget1(1, DLMtool::Atlantic_mackerel, plot=TRUE)
#> TAC (median) 
#>     6.970583 
Itarget2(1, DLMtool::Atlantic_mackerel, plot=TRUE)
#> TAC (median) 
#>      7.07242 
Itarget3(1, DLMtool::Atlantic_mackerel, plot=TRUE)
#> TAC (median) 
#>     7.055202 
Itarget4(1, DLMtool::Atlantic_mackerel, plot=TRUE)
#> TAC (median) 
#>     4.978327