Stock Synthesis 2
(SS2)

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.

For more information on the SS2 model, see the In-Depth Introduction to SS2.

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.

Back to Top 

Download Stock Synthesis 2 Now

Additional downloads are available:

• Simple SS2 Example Files

• Additional SS2 Example Files

• SS2 Technical Documentation

Back to Top 

Screen shot of of the length composition input data grid:

Screen shot of recruitment model options:

Screen shot of an example output plot:

Back to Top 

SS2 Version 2.00n (December 2007)

Includes calculation engine version 2.00n (November 2007)

• Primarily a calculation engine update

Back to Top 

Older Version Changes