Eggs-per-recruit(EPR) analysis is conducted following Gabriel et al. (1989) except fecundity-at-age is substituted for weight-at-age. Reference points of F and EPR for percentage of maximum spawning potential are calculated.
epr(age = NULL, fecund = NULL, partial = NULL, pmat = pmat,
M = NULL, pF = NULL, pM = NULL, MSP = 40, plus = FALSE,
oldest = NULL, maxF = 2, incrF = 1e-04)
F and EPR values for the percentage MSP
Eggs-per-recruit values for each F increment
vector of cohort ages. If the last age is a plus group, do not add a "+" to the age.
vector of fecundity (number of eggs per individual) for each age. Length of vector must correspond to the length of the age vector.
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.
proportion of mature fish at each age. Length of this vector must match the length of the age vector.
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 match the length of the age vector.
the proportion of fishing mortality that occurs before spawning.
the proportion of natural mortality that occurs before spawning.
the percentage of maximum spawning potential (percent MSP reference point) for which F and EPR should be calculated.
a logical value indicating whether the last age is a plus-group. Default is FALSE.
if plus=TRUE, a numeric value indicating the oldest age in the plus group.
the maximum value of F range over which EPR will be calculated. EPR is calculated for F = 0 to maxF.
F increment for EPR calculation.
Gary A. Nelson, Massachusetts Division of Marine Fisheries gary.nelson@mass.gov
Eggs-per-recruit analysis is conducted following Gabriel et al. (1989). The F and EPR 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 fecund, partial, pmat, and M values for the plus age are applied to the expanded cohort ages.
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.
ypr sbpr
data(menhaden)
epr(age=menhaden$age,fecund=menhaden$fecundity,partial=menhaden$partial,
pmat=menhaden$pmat,M=menhaden$M,pF=0,pM=0,MSP=40,plus=TRUE,maxF=4,incrF=0.01,oldest=10)
Run the code above in your browser using DataLab