Uncertainty about the magnitude, frequency, location, and timing of stock-specific sockeye and chum salmon harvest in Western Alaska fisheries was the impetus for the Western Alaska Salmon Stock Identification Program (WASSIP). The program was designed to use genetic data in mixed stock analysis of fisheries samples to more clearly describe harvest patterns of sockeye and chum salmon stocks in Western Alaska fisheries (from Chignik Area to Kuskokwim Area for sockeye salmon). Stock composition estimates for temporal strata across fisheries are required to estimate stock-specific harvest numbers and rates. This report describes the methodology used to estimate stock compositions for sockeye salmon, presents stock composition estimates, and provides guidance on how to interpret biases documented in the genetic baseline. While 81,482 tissue samples from 216 strata were originally selected, 83,393 samples from 217 strata were included in final analyses. Trends in stock composition estimates were observed across fisheries and within and among years. The majority of catches within Chignik, Bristol Bay, and Kuskokwim areas consisted of stocks originating in those areas. Alaska Peninsula Area fisheries catches were more diverse. In Southeastern District Mainland fisheries, South Peninsula, Chignik, and East of WASSIP stocks were most represented. In the June Shumagin Island Section, Ikatan area, and Unimak District fisheries, Bristol Bay stocks were most represented. The June Dolgoi Islands fishery captured mostly Bristol Bay, Chignik, and East of WASSIP stocks. Post-June fisheries along the South Peninsula captured fewer Bristol Bay stocks and more Chignik and East of WASSIP stocks than June fisheries, with strong contributions from all three. Stock compositions of North Peninsula fisheries were mostly North Peninsula stocks in the western sections of the District and transitioned to mostly Bristol Bay stocks in the eastern sections. These results provide the most comprehensive examination of stock compositions across Western Alaska sockeye salmon fisheries.