This document covers the massive decline in catch and return on trout stocked in Diamond Lake starting in the 90s and describes issues addressing the most likely cause, an increased Tui chub population competing for resources with the trout. The report discusses the persistent issue of Tui chub in Diamond...
"In January 1946 the Oregon State Game Commission authorized a study of Diamond Lake to determine reason for an apparent decline in the size and number of rainbow trout with the object of maintaining a maximum annual yield through proper management." (From Introduction)