Why are paddlefish relatively common in the Williston area when they’re so rare or no longer present in other areas within their range?

The short answer is habitat quality for paddlefish, which is generally much better for all life stages in Lake Sakakawea and the Yellowstone and Missouri rivers than elsewhere. Paddlefish are finicky spawners, requiring a combination of high flows, right water temperature, and a good substrate of clean gravel and cobble. The Yellowstone River is still a free-flowing, naturally fluctuating river that provides adequate spawning habitat most years. When Lake Sakakawea has a high water level, paddlefish generally find abundant food for growth and maturation. During extended periods of low lake levels, however, plankton is far less abundant, and survival of young paddlefish is greatly reduced.

In other parts of its range, habitat quality is generally much poorer. Dam construction, dredging, channelization, and excessive water withdrawals for irrigation and municipal and industrial use have significantly changed most large rivers in North America. Few rivers today provide the proper combinations of flow, temperature and gravel substrates suitable for paddlefish spawning. In many states, paddlefish populations have been greatly reduced or even eliminated because of lost spawning habitat.