Well, Smb only live about 7 years, males have a shorter life expectancy and spawn at 3 or 4 years depending on thier size. Males spawn no more than two times and ussaly one. So most males do not survive to be 6.
Fishbase.org is the place I go when I need specifics on any given fish. Here is their site for SMB
http://www.fishbase.org/Summary/SpeciesSummary.cfm?genusname=Micropterus&speciesname=dolomieu Notice they have a link to growth estimates and data. All thier graphs are in log scale and using complex formulas to estimate length, weight, and mortality. I didn't completly grasp it, but I'm working on it.
