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.
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age |
vector of cohort ages. If the last age is a plus group, do not add a "+" to the age. |
fecund |
vector of fecundity (number of eggs per individual) 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 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 SBPR will be calculated. SBPR is calculated for F = 0 to maxF. |
incrF |
F increment for SBPR calculation. |
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.
Reference_Points |
F and EPR values for the percentage MSP |
EPR_vs_F |
Eggs-per-recruit values for each F increment |
Gary A. Nelson, Massachusetts Division of Marine Fisheries gary.nelson@state.ma.us
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
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