I have ask many Native Americans the same question and here are some of their answers. We fish for the same reasons you sportfish. It is an obsession, a way of life. It is something we enjoy doing. We are simply acting upon and protecting our court ordered treaty rights. We are practicing our local and tradional customs. It is a way to protect our heritage. For religious and ceremonial purposes etc.
I am not condoning these answers but remember that there are good and bad tribal fishers just like there are good and bad sportfishers.