ypr: Yield-Per-Recruit Analysis

In fishmethods: Fishery Science Methods and Models

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

ypr(age = NULL, wgt = NULL, partial = NULL, M = NULL,
 plus = FALSE, oldest = NULL, maxF = 2, incrF = 0.001, graph = TRUE)

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 [e-mail]

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

data(haddock)
ypr(age=haddock$age,wgt=haddock$ssbwgt,partial=haddock$partial,M=0.4,
plus=TRUE,oldest=100,maxF=2,incrF=0.01)

fishmethods documentation built on April 27, 2023, 9:10 a.m.