In previous versions of FSA, growthModelSim() was used to produce a scatterplot of length-age data with a von Bertalanffy model superimposed where the parameters of the model were linked to slider bars that allowed the model to be dynamically changed by the user.  This function has been removed from the most recent version of FSA, but the functionality is still available by using dynamicPlot=TRUE in vbStarts().  This change made it easier to create a useful range of values for the slider bars.

I have also completely re-written the code in vbStarts().  I believe that it is more robust (and it is definitely easier to follow, which will make troubleshooting easier).

You should update your FSA package (instructions here) to use this enhanced functionality.  The Growth chapter in the Introduction to Fisheries Analysis with R book has also been updated.

For those of you looking for the old growthModelSim(), it is now in the FSASim package.

Let me know if you have questions or find any bugs.