Mixed-stock fisheries are systems that consist of multiple populations of fish with sizes amenable to resource management and are harvested simultaneously. When different stocks have varying levels of abundance, productivity, and vulnerability to fishing pressure, fishery managers often are faced with the competing objectives of protecting the more vulnerable stocks while maximizing sustainable harvest on remaining healthy stocks. The challenges associated with managing a mixed-stock fishery are typified by the Columbia River fall-run Chinook fishery at the mouth. The fishery includes numerous fall-run stocks with eight separate fall-run management components, including two protected stocks: Snake River wild brights and Lower Columbia River tules. The recreational fishery is an important economic benefit to the surrounding communities, generating over $25M/year depending on season length.To further complicate the management, a growing number of the recreational anglers believe that they can identify tule Chinook from upriver brights and purport to release an unknown portion of their catch (those identified as tules) to ensure that the season is open as long as possible. Thus, management of the fishery requires reliable estimates of in-season harvest, while taking into account changes in angler behavior. Our objectives are to develop the tools (including novel assessment methods and regulatory options) and systemic understanding necessary to promote effective management of the mixed-stock fishery in the face of existing conservation priorities and changing angler behavior.