Southern Chum stock strength must be monitored to facilitate their management, in accordance with Annex IV, Chapter 6 of the Pacific Salmon Treaty (Treaty). Catch composition in fisheries targeting Southern origin Chum populations informs managers of stock strength, mixed fishery components and exploitation rates. . We are proposing to sample Southern BC and US mixed stock Chum fisheries to determine stock composition to the levels of Canadian Conservation Unit (CU) and United States Management Unit (MU) level using genetic mixed stock analysis. Along with other stock assessment information, such as escapement, the data provided from this work is a critical component required by the ChumGEM model for run-reconstruction and eventually for forecasting run strength. This proposal follows from a previous Southern Fund project ‘Joint US and CA mixed-stock Chum fisheries sampling design’ which occurred 2012-2015. The goal is to assess the mixed stock Chum fisheries for four consecutive years in a multi-agency sampling effort.