DLMtool (version 5.4.5)

EtargetLopt: Effort Target Optimum Length

Description

This MP adjusts effort limit based on the ratio of recent mean length (over last yrsmth years) and a target length defined as $L_{\text{opt}}$. Effort MP: adjust effort up/down if mean length above/below Ltarget

Usage

EtargetLopt(x, Data, reps = 100, plot = FALSE, yrsmth = 3, buffer = 0.1)

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 with the TAE slot(s) populated

Required Data

See '>Data for information on the Data object

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

Rendered Equations

See Online Documentation for correctly rendered equations

Details

The TAE is calculated as: $${\text{TAE}}_y={\text{TAE}}_{y-1}((1-\text{buffer})(w+(1-w)r))$$ where $\text{buffer}$ is specified in argument buffer, $w$ is fixed at 0.5, and: $$r=\frac{L_{\text{recent}}}{L_{\text{opt}}}$$ where $L_{\text{recent}}$is mean length over last yrmsth years, and: $$L_{\text{opt}}=\frac{L_{\mathrm{\infty }}{W}_b}{\frac{M}{K}+W_b}$$ where $L_{\mathrm{\infty }}$ 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.#'

Examples

# NOT RUN {
EtargetLopt(1, DLMtool::SimulatedData, plot=TRUE)
# }