Hello Robert -
        I have used MIX software from Ichthus Data Systems in Canada to fit
fish length frequency data to Von Bertallanfy growth curves.  This
program is available for IBM's and clones (and I believe UNIX boxes) as
well as Macintosh (which I use).  I'm not sure if anyone has ever used
it for turtle data.  The authors (Peter McDonald is one that I remember
off hand) offer to help people use the program, for free.

        Since I am at home now, I don't have the complete reference and address
available.  I could get it to you on the 7th of Jan. when I return to
work if you still need it.

        Good luck,

--Craig Lilyestrom
   Marine Resources Division
                        P.R. DNER, San Juan, Puerto Rico