From http://www.learnalaska.org/lessonplans/fishwheels_lesson.pdf
The origin of fish wheels is not certain. Many historians believe the fish wheel originated in China and was adapted from the water wheels used in the irrigation of rice fields. The buckets of the water wheels may have incidentally caught fish. Another theory suggests the fish wheel was developed independently in North Carolina around the 1780’s. Fish wheels were used in the Columbia River in Oregon and Washington and in the Sacramento River in California from 1879 through 1934. The origin of these wheels is unknown.
From these West Coast origins, the fish wheel came to Alaska in 1904, and was first used by whites on the Tanana River. It is now a very popular device on the Kuskokwim, Copper, Yukon, Tanana, and most other large Interior rivers in the state.
Several theories speculate on how the fish wheel arrived in Alaska. First, some historians believe miners introduced fish wheels in Alaska in the early 1900’s. This theory is the most widely accepted.
The fish wheel baskets are kept turning by the thrust of the river current. Salmon migrate upstream swimming against the current. The rotating baskets comes up under the fish and scoops the fish out of the water as the basket approaches its vertical point, the fish slides downward to the angled trough and into the box on the base of the wheel. Fish wheels are a major improvement over dip and set nets as they can capture fish in muddy waters and can be operated 24 hours a day. People can be processing fish for drying while the fish wheel collects additional fish.