# Length Target TAE MP

`LtargetE1.Rd`

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.

## Value

An object of class `Rec-class`

with the TAE slot(s) populated

## Details

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

The TAE is calculated as:

If \(L_\textrm{recent} \geq L_0\): $$\textrm{TAE} = 0.5 \textrm{TAE}^* \left[1+\left(\frac{L_\textrm{recent}-L_0}{L_\textrm{target}-L_0}\right)\right] $$

else: $$\textrm{TAE} = 0.5 \textrm{TAE}^* \left[\frac{L_\textrm{recent}}{L_0}^2\right] $$

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`

\(L_\textrm{ave}\).

## Functions

`LtargetE1`

: The least biologically precautionary TAE-based MP.`LtargetE4`

: The`xL`

argument is increased to 1.15.

## 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 Length target MPs:
`Lratio_BHI()`

,
`Ltarget1()`

## Examples

```
LtargetE1(1, Data=MSEtool::SimulatedData, plot=TRUE)
#> Effort
#> 0.85
LtargetE4(1, Data=MSEtool::SimulatedData, plot=TRUE)
#> Effort
#> 0.85
```