Yield per Recruit (YPR) is a major revision of earlier
implementations of the basic Thompson-Bell model for estimating the
lifetime yield and biomass from a cohort subjected to varying levels of
The present version estimates life-history parameters such as mean age,
generation time, and expected number of spawnings.In addition the user can investigate the
resulting age composition of catch and abundance under different levels of
The latest version of YPR allows the user to incorporate uncertainty in
weights at age, natural mortality, maturity, and fishery selectivity.
The user can optionally enter the coefficients of either a Beverton-Holt
Ricker stock recruitment relationship and perform a Sissenwine-Shepherd
analysis for equilibrium estimates of maximum sustainable yield (MSY)
points (FMSY and BMSY).
The user can also conduct sensitivity analyses for any model parameter.
visualization methods are emphasized to allow exploration of the
consequences of changes in fishing mortality.
Gabriel, W.L., M. P. Sissenwine, and W.
J. Overholtz. 1989. Analysis of spawning stock biomass per recruit: An
example of Georges Bank haddock. North American Journal of Fisheries
Management 9:383-391, 1989.
Thompson, W.F. and F.H Bell. 1934.
Biological statistics of the Pacific halibut fishery. (2) Effects of
changes in intensity upon total yield and yield per unit of gear.
International Fisheries Commission Report, No. 8, 1934.
Added ability to include uncertainty to
vectors which have traditionally been assumed constant: weights at age,
mortality, maturity, and fishery selectivity. Sensitivity analysis
allow wider range of conditions to be explored.
2.7.1 (May 2007)
a bug where selecting Create
a New Case from the File
menu caused the GUI to crash.