Effort Target Optimum Length
EtargetLopt.RdThis 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
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, vbK, vbLinf, wlb
Rendered Equations
See Online Documentation for correctly rendered equations
Author
HF Geromont
Examples
#> Effort #> 0.7915114
