DLMtool (version 5.2)

Itarget1: Incremental Index Target MP

Description

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.

Usage

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 a data-limited methods data object

Data

A data-limited methods data object

reps

The number of stochastic samples of the MP recommendation(s)

plot

Logical. Show the plot?

yrsmth

Years over which to smooth recent estimates of surplus production

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

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

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.

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

# NOT RUN {
Itarget1(1, DLMtool::Atlantic_mackerel, plot=TRUE)
Itarget2(1, DLMtool::Atlantic_mackerel, plot=TRUE)
Itarget3(1, DLMtool::Atlantic_mackerel, plot=TRUE)
Itarget4(1, DLMtool::Atlantic_mackerel, plot=TRUE)
# }