LtargetE1 {DLMtool} R Documentation

## Length Target TAE MP

### Description

A management procedure that incrementally adjusts the TAE to reach a target mean length in catches.

### Usage

LtargetE1(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xL = 1.05)

LtargetE4(x, Data, reps = 100, plot = FALSE, yrsmth = 5, xL = 1.15)


### 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 mean length xL Parameter controlling the magnitude of the target mean length of catches relative to average length in catches.

### Details

Four target length MPs proposed by Geromont and Butterworth 2014. Tested by Carruthers et al. 2015.

The TAE is calculated as:

If L_\textrm{recent} ≥q L_0:

\textrm{TAE} = 0.5 \textrm{TAE}^* ≤ft[1+≤ft(\frac{L_\textrm{recent}-L_0}{L_\textrm{target}-L_0}\right)\right]

else:

\textrm{TAE} = 0.5 \textrm{TAE}^* ≤ft[\frac{L_\textrm{recent}}{L_0}^2\right]

where \textrm{TAE}^* is the effort in the previous year, L_\textrm{recent} is mean length in last yrmsth years, L_0 is (except for L95target) 0.9 average catch in the last 2 x yrsmth historical (pre-projection years) (L_\textrm{ave}), and L_\textrm{target} is (except for L95target) xL L_\textrm{ave}.

### Value

An object of class Rec-class with the TAE slot(s) populated

### Functions

• LtargetE1: The least biologically precautionary TAE-based MP.

• LtargetE4: The xL argument is increased to 1.15.

### Required Data

See Data-class for information on the Data object

LtargetE1: LHYear, ML, MPeff, 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. doi:10.1093/icesjms/fst232

Other Length target MPs: Lratio_BHI(), Ltarget1()
LtargetE1(1, Data=MSEtool::SimulatedData, plot=TRUE)