The early females were there getting some food to help with the up coming spawn. The young males that you are catchibng are starting to move towards the spawning grounds. The larger males will move in and chase the smaller males out. The bigger the males the better the spawning nest area. Once I catch a few large males I'll return to the same spot in a couple of days and fresh males will move onto the spot. The water temps need to be in the lower 60's to the upper 60's for the actual spawn. But anytime the the fish are up close to the bank the spawn can't be to far behind.