So Van and I walked into this scenario today. Carp everywhere, and 99 percent of them spawning. I think yesterday's sun bumped the temps up and every carp in the area flooded the fields and had a good old time getting down. We heron stalked through their midsts, and stuck some decent fish...including Van's first, second, and third ever carp on the fly. The obligatory Statue of Liberty pose.
Three things played heavily into your success with these fish. First, we needed a heavy fly to punch through the blades of grass and general vegetation surrounding the fish. Second, targets: if the fish were moving on this day, they were spawning...casting at sedentary fish (preferably with their mouths pulsing) was the key. Third (and something that is always true) was stealth. Spawning fish are NOT spooky, but if you are inching closer to a perfect, laid up fish and you step on, or move quickly and spook the spawners they blow a lot of fish in a hurry.