Saltwater fishermen often run the tide, moving from spot to spot within a bay or coastal creek to take advantage of a certain water depth where fish are biting.

On North Carolina’s Kerr Reservoir, guide Chris Bullock runs the spawn — the crappie spawn. He can get several weeks of top-drawer, prespawn fishing for slab crappie in March because he knows where they’ll spawn first, where they’ll spawn next, and when they’ll be thinking about mostly about feeding before they spawn.

Bullock, a native of Fountain, N.C., who runs Kerr Crappie and Cats Guide Service, knows that crappie are at their largest in the days before they head to the shallows to spawn, and he keys on the movement of fish in different areas of Kerr Lake, aka Buggs Island, to make sure he’s on them at the right time.

“The spawn starts up around Clarksville, Va., and it progresses downstream,” Bullock said. “They spawn first up there; they work their way down. When the water temperature gets to about 52 degrees, they’re raring to go.”

What Bullock keys on are brush piles along the channels in creeks up and down the 49,500-acre reservoir along the North Carolina-Virginia border. When he can find slabs around brush in 8 to 12 feet of water back in the creeks, he knows the spawn hasn’t arrived, and he knows they’ll be biting. When fish leave the brush, he said they head for shallow, spawning flats, and the move can be so fast that fish are here today, gone tomorrow.

One windy, cloudy March day in 2016, Bullock was scouting for a crappie trip the next day, having