Effort Target Optimum Length — EtargetLopt • DLMtool Functions

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

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-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

Author

HF Geromont

Examples

EtargetLopt(1, MSEtool::SimulatedData, plot=TRUE)

#>    Effort 
#> 0.8003528