Jimk, how big and where is your pond? I really wouldn't worry about the frogs at all. The crawfish here in Ms. usually feed on plants weeds etc. That's not to say that they won't eat bgill fry.
It is natural to have concerns about what you can't see going on in your pond. The bgill are there and they will reproduce many times in the course of a year.
Enjoy your pond and don't worry until you do see something wrong. Good luck.