EtargetLopt: Effort Target Optimum Length

In DLMtool/DLMtool: Data-Limited Methods Toolkit

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_{\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

Details

The TAE is calculated as:

\textrm{TAE}_y = \textrm{TAE}_{y-1} ≤ft((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_∞ W_b}{\frac{M}{K} + W_b }

where L_∞ 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.#'

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

Author(s)

HF Geromont

Examples

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

DLMtool/DLMtool documentation built on June 20, 2021, 5:20 p.m.