Rexburg isn't exactly warm water territory, and I never chase those species so I'm not gonna be much help.
You mentioned the salmon in Ririe. The kokes there haven't produced good reports this year. It's not the best ice producer but it sounds like we got a reasonable sheet there before all the snow came. A place for extra caution, especially if you plan to explore much.
Have you been to Island Park Reservoir? Big trout there when you can get them interested. Ashton Res is also a trouty place. Not sure what else is in there.
Hey folks, Joe is a good dude and a good friend. Please get him any info you might have, via PM if necessary.