More for hunting than fishing but I use to have an 8 1/2" X 11" sheet of paper laminated with Name, Address, Phone Numbers, License Plate and Car Make that I would give people who gave me permission. I would tell them that I wanted them to know who was on their land. It went over really well. Always leave the place as you found it or better. If I found some junk while out, I would pick it up. There are enough irresponsible people out there that if you act responsible it goes a long way.
Rick