Before Glen Canyon Dam and Lake Powell, native fish lived in the free-flowing Colorado River. They had unique physical adaptations that allowed them to thrive in the river's often murky water.
But they could not survive in the still, deep waters that form Lake Powell's new ecosystem. Non-native game fish such as bass, bluegill, crappie, catfish and shad have taken their place.
Striped bass have done especially well. Stocked in the lake in 1974, they surprised people by naturally reproducing. Stripers eat mostly shad, and their numbers reflect a "boom and bust" cycle depending on abundance of their prey.
Striped bass have been so successful that they now support a popular sport fishery on Lake Powell. There's no creel limit on them; anglers have taken 80 to 100 a day. In 2006, almost 2 million striped bass were caught in the lake. Trophy-sized catches are not uncommon. The record striper so far, weighed nearly 50 pounds.
Wayne Gustaveson is a fisheries manager at Lake Powell who maintains a blog with tips on where to find striper action. One is, watch for large schools of fish feeding close to the surface in churning "boils" visible from a mile away. Savvy anglers also learn to watch where herons, ravens and coyotes congregate.
Lower lake levels in recent years haven't seemed to hurt stripers. But invasive mussels, if they arrive, could completely alter the ecosystem. For now, striped bass are the big fish story in a big and no-so-secret fishing hole.