Stock Synthesis
2 (SS2) provides a statistical framework for
calibration of a population dynamics model using a diversity of fishery
and survey data. SS2 is designed to accommodate both age and size
structure and with multiple stock sub-areas. Selectivity can be cast as
age specific only, size-specific in the observations only, or
size-specific with the ability to capture the major effect of
size-specific survivorship. The overall model contains subcomponents
which simulate the population dynamics of the stock and fisheries,
derive the expected values for the various observed data, and quantify
the magnitude of difference between observed and expected data.
Parameters are searched for which will maximize the goodness-of-fit. A
management layer is also included in the model allowing uncertainty in
estimated parameters to be propagated to the management quantities,
thus facilitating a description of the risk of various possible
management scenarios. The structure of SS2 allows for building of
simple to complex models depending upon the data available.
Stock Synthesis 2 is a conversion of the FORTRAN code for
Stock Synthesis to C++ code with AD Model Builder by Dr. Richard Methot
of the NMFS Northwest Fisheries Science Center and NMFS Office of
Science and
Technology.
In June 2006, SS2 (calculation engine version 1.23d) became
available from the NOAA Fisheries
Toolbox with a sophisticated graphical user interface. The graphical
interface was developed at the NMFS Northeast Fisheries Science Center.
