I have a question and would value your thoughts to how best address this.  What do you think would be the best way to demonstrate the positive impact of a bycatch reduction device on local populations (of sharks).  Have CPUE and length data.  BRD significantly reduces CPUE for some species but wonder if there is a way to show the benefit (if any) to the population in a numerical sence. 

I have some ideas and would value any of your opinions.
Thankyou
K. LeFeaux