hatchery smolts have a tencendy to chew on each others fins ( or so the rumor is) best bet if there is no adipose fin is to look for a mangaled dorsal. When in doubt let it go!! And for the time of year go expecting to release them all. if you get to bonk a for sure brat thats great but go expecting to enjoy the fishing not to fill your freeser! That should be true with any fishing trip at any time of year!