IIRC, the ratio of LMB that were caught by anglers of pure 13 pound Florida LMB vs. a Northern/Florida mix was right at 50/50 in the TX Share a Lunker program.
What I wonder about is the actual numbers of the resident LMB caught. Are the mixed LMB more aggressive, and therefore skew the results of the fish caught, or are there really as many mixed as pure strain LMB growing to 13+ pounds?