sbpr: Spawning Stock Biomass-Per-Recruit Analysis

In fishmethods: Fishery Science Methods and Models

Spawning Stock Biomass-Per-Recruit Analysis

Description

Spawning stock biomass-per-recruit(SBPR) analysis is conducted following Gabriel et al. (1989). Reference points of F and SBPR for a percentage of maximum spawning potential are calculated.

Usage

 sbpr(age = NULL, ssbwgt = NULL, partial = NULL, pmat = pmat,
 M = NULL, pF = NULL, pM = NULL, MSP = 40, plus = FALSE,
 oldest = NULL, maxF = 2, incrF = 1e-04, graph = TRUE)

Arguments

age	vector of cohort ages. If the last age is a plus group, do not add a "+" to the age.
ssbwgt	vector of spawning stock weights for each age. Length of vector must correspond to the length of the age vector.
partial	partial recruitment vector applied to fishing mortality (F) to obtain partial F-at-age. Length of this vector must match length of the age vector.
pmat	proportion of mature fish at each age. Length of this vector must match 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 match the length of the age vector.
pF	the proportion of fishing mortality that occurs before spawning.
pM	the proportion of natural mortality that occurs before spawning.
MSP	the percentage of maximum spawning potential (percent MSP reference point) for which F and SBPR should be calculated.
plus	a logical indicating whether the last age is a plus-group. Default=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 SBPR will be calculated. SBPR is calculated for F = 0 to maxF.
incrF	F increment for SBPR calculation.
graph	a logical indicating whether SPR and Percent Max SPR versus F should be plotted. Default=TRUE.

Details

Spawning stock biomass-per-recruit analysis is conducted following Gabriel et al. (1989). The F and SBPR for the percentage maximum spawning potential reference point are calculated. If the last age is a plus-group, the cohort is expanded to the oldest age and the ssbwgt, partial, pmat, and M values for the plus age are applied to the expanded cohort ages.

Value

Reference_Points	F and SBPR values for the percentage MSP
SBPR_vs_F	Spawning stock biomass-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

ypr

Examples

data(haddock)
sbpr(age=haddock$age,ssbwgt=haddock$ssbwgt,partial=haddock$partial,
pmat=haddock$pmat,M=0.2,pF=0.2, pM=0.1667,MSP=30,plus=FALSE,maxF=2,
incrF=0.001)		

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