# Yield-Per-Recruit Analysis

### Description

Yield-per-recruit (YPR) analysis is conducted following the modified Thompson-Bell algorithm. Reference points Fmax and F0.1 are calculated.

### Usage

1 2 |

### Arguments

`age` |
the vector of cohort ages, e.g. c(1,2,3,4,5). If the last age is a plus group, do not add a "+" to the age. |

`wgt` |
the vector of catch weights for each age, e.g. c(0.2,0.4,0.7,1.0,1.2). Length of vector must correspond to the length of the age vector. |

`partial` |
the partial recruitment vector applied to fishing mortality (F) to obtain partial F-at-age. Length of the partial recruitment vector must correspond to the length of the age vector. |

`M` |
vector containing a single natural mortality (M) rate if M is assumed constant over all ages, or a vector of Ms, one for each age. If the latter, the vector length must correspond to the length of the age vector. |

`plus` |
a logical value indicating whether the last age is a plus-group. Default is FALSE. |

`oldest` |
if plus=TRUE, a numeric value indicating the oldest age in the plus group. |

`maxF` |
the maximum value of F range over which YPR will be calculated. YPR is calculated for F = 0 to maxF. |

`incrF` |
F increment for YPR calculation. |

`graph` |
logical indicating whether YPR versus F should be plotted. Default=TRUE. |

### Details

Yield-per-recruit analysis is conducted following the modified Thompson-Bell algorithm. Reference points
Fmax and F0.1 are calculated. If the last age is a plus-group, the cohort is expanded to the
`oldest`

age and the `wgt`

, `partial`

, and `M`

values for the plus age are applied to the expanded cohort ages.

### Value

`Reference_Points` |
F and yield-per-recruit values for Fmax and F0.1 |

`F_vs_YPR ` |
Yield-per-recruit values for each F increment |

### Author(s)

Gary A. Nelson, Massachusetts Division of Marine Fisheries gary.nelson@state.ma.us

### References

Gabriel, W. L., M. P. Sissenwine, and W. J. Overholtz. 1989. Analysis of spawning stock biomass per recruit: an example for Georges Bank haddock. North American Journal of Fisheries Management 9: 383-391.

### See Also

`sbpr`

### Examples

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