Thank you for your question. Here is some information from the SS Team:
SS does internally calculate an ALK and is written to the output file, report.sso. Look for the keyword AGE_LENGTH_KEY. The age-length-key is calculated based on the mean and variance of length-at-age using parameters in the control file. Although the process of creating "age data" by converting lengths to ages using an ALK is commonly done in some places, we do not recommend this approach for assessment in general and not within SS. You say that you have an age-length key, so I assume that you have some age data in that key but not enough to expand to a complete age composition observation. SS has a feature that allows use of age data as conditional age-at-length. Basically each row, or range of rows, of your age-length key can be entered into SS to greatly improve SS' ability to estimate growth parameters and use the age data to help estimation of recruitment. This feature is described in the manual.
Rick and the SS Team
