# YPR: Yield Per Recruit analysis to get FMSY proxy F01 In DLMtool: Data-Limited Methods Toolkit

## Description

A simple yield per recruit approximation to FMSY (F01) which is the position of the ascending YPR curve for which dYPR/dF = 0.1(dYPR/d0)

## Usage

 ```1 2 3 4 5``` ```YPR(x, Data, reps = 100, plot = FALSE) YPR_CC(x, Data, reps = 100, plot = FALSE, Fmin = 0.005) YPR_ML(x, Data, reps = 100, plot = FALSE) ```

## 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? `Fmin` The minimum fishing mortality rate inferred from the catch-curve analysis

## Details

The TAC is calculated as:

\textrm{TAC} = F_{0.1} A

where F_{0.1} is the fishing mortality (F) where the slope of the yield-per-recruit (YPR) curve is 10% of the slope at the origin, and A is an estimate of current abundance.

The YPR curve is calculated using an equilibrium age-structured model with life-history and selectivity parameters sampled from the `Data` object.

The variants of the YPR MP differ in the method to estimate current abundance (see Functions section below). #'

## Value

An object of class `Rec` with the `TAC` slot populated with a numeric vector of length `reps`

## Functions

• `YPR`: Requires an external estimate of abundance.

• `YPR_CC`: A catch-curve analysis is used to determine recent Z which given M (Mort) gives F and thus abundance = Ct/(1-exp(-F))

• `YPR_ML`: A mean-length estimate of recent Z is used to infer current abundance.

## Required Data

See Data for information on the `Data` object

`YPR`: Abun, LFS, MaxAge, vbK, vbLinf, vbt0

`YPR_CC`: CAA, Cat, LFS, MaxAge, vbK, vbLinf, vbt0

`YPR_ML`: CAL, Cat, LFS, Lbar, Lc, MaxAge, Mort, vbK, vbLinf, vbt0

## Rendered Equations

See Online Documentation for correctly rendered equations

## Note

Based on the code of Meaghan Bryan

## Author(s)

Meaghan Bryan and Tom Carruthers

## References

Beverton and Holt. 1954.

## Examples

 ```1 2 3``` ```YPR(1, DLMtool::SimulatedData, plot=TRUE) YPR_CC(1, DLMtool::SimulatedData, plot=TRUE) YPR_ML(1, DLMtool::SimulatedData, plot=TRUE) ```

DLMtool documentation built on Dec. 6, 2019, 9:06 a.m.