Itarget1 {DLMtool} R Documentation

## 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

### 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 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.

### Details

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

The TAC is calculated as: If I_\textrm{recent} ≥q I_0:

\textrm{TAC}= 0.5 \textrm{TAC}^* ≤ft[1+≤ft(\frac{I_\textrm{recent} - I_0}{I_\textrm{target} - I_0}\right)\right]

else:

\textrm{TAC}= 0.5 \textrm{TAC}^* ≤ft[\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.

### Value

An object of class Rec-class 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-class for information on the Data object

Itarget1: Cat, Ind, LHYear, Year

### Rendered Equations

See Online Documentation for correctly rendered equations

T. Carruthers

### 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

Other Index methods: GB_slope(), GB_target(), Gcontrol(), ICI(), Iratio(), Islope1(), Itarget1_MPA(), ItargetE1()
Itarget1(1, MSEtool::Atlantic_mackerel, plot=TRUE)