These environmental factors don't coincide every year. Thus, female paddlefish may not spawn every year. When spawning does occur, it is a simple act. A large female, accompanied by a couple of usually smaller males, swims over the selected gravel bar. Both sexes release their respective eggs and milt.
Fertilization occurs in the water and the eggs become sticky.
The sticky eggs adhere to the gravel substrate so that they don't wash away. The high water flow keeps the eggs well-oxygenated and keeps debris and silt from covering them. In about a week, the eggs hatch and the larval paddlefish are swept downstream to quieter nursery waters. In a few days, the yolk sac is absorbed and the young fish feed first on small insects. Then they begin their lifelong pursuit of zooplankton.