Dual Zone VPA Model (VPA-2BOX) is a flexible
software tool for analyzing the abundance and mortality of exploited
animal populations that is based on the ADAPT framework developed by
Parrack (1986) and Gavaris (1988).
The primary difference between this package and other versions
of ADAPT is the capability of analyzing two different stocks
simultaneously, making possible routine quantitative analyses of the
effect of sex-specific growth or stock intermixing. In addition, a wide
variety of options are provided with respect to the types of data that
may be used and the way the parameters are estimated. The flexible
interface allows the user to configure and test reduced model
allows the user to specify
either single or dual zones with independent specification of catch and
surveys. The user may also introduce tagging data into the
dual zone configuration to account for mixing of the two populations.
Users may specify parameters to be linked and introduce
has been used in the NMFS Southeast Fisheries
Science Center as an assessment tool for a number of years.
The program was developed by Dr. Clay Porch at the NMFS,
Southeast Fisheries Science Center.
The incorporation of this model into the Toolbox adds a
comprehensive graphical interface to this model thus opening it to a
potentially larger user audience. The new graphical interface allows
the user to manipulate and visualize the large amount of input data,
specify model structure, control the estimation methodology,
and review model results.