# Effort Target Optimum Length

`EtargetLopt.Rd`

This MP adjusts effort limit based on the ratio of recent mean length (over
last `yrsmth`

years) and a target length defined as \(L_{\textrm{opt}}\).
Effort MP: adjust effort up/down if mean length above/below Ltarget

## 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
Number of years to calculate average length

- buffer
Parameter controlling the fraction of calculated effor - acts as a precautionary buffer

## Value

An object of class `Rec-class`

with the TAE slot(s) populated

## Details

The TAE is calculated as:
$$\textrm{TAE}_y = \textrm{TAE}_{y-1} \left((1-\textrm{buffer}) (w + (1-w)r) \right)$$
where \(\textrm{buffer}\) is specified in argument `buffer`

, \(w\) is fixed at 0.5, and:
$$r = \frac{L_{\textrm{recent}}}{L_{\textrm{opt}}}$$
where \(L_{\textrm{recent}}\)is mean
length over last `yrmsth`

years, and:
$$L_{\textrm{opt}} = \frac{L_\infty W_b}{\frac{M}{K} + W_b }$$
where \(L_\infty\) is von Bertalanffy asymptotic length, \(W_b\) is
exponent of the length-weight relationship, \(M\) is natural mortality, and
\(K\) is von Bertalanffy growth coefficient.#'

## Required Data

See `Data-class`

for information on the `Data`

object

`EtargetLopt`

: ML, MPeff, Mort, Year, vbK, vbLinf, wlb

## Rendered Equations

See Online Documentation for correctly rendered equations

## Examples

```
EtargetLopt(1, MSEtool::SimulatedData, plot=TRUE)
#> Effort
#> 0.8003528
```