These data are estimates of the proportional contributions of bearded seal, beluga whale, bowhead whale, and ringed seal to the diets of southern Beaufort Sea polar bears. Fat biopsy samples were collected from polar bears captured or biopsy darted along the north coast of Alaska or on offshore ice during March, April, and May from 2004 to 2016. Fatty acid data of the above four prey species were compiled from online sources (Bromaghin et al. 2015ab, USGS 2021) and one private source that has been used in several polar bear diet studies (Thiemann et al. 2008). Diet composition was estimated from polar bear adipose tissue fatty acid composition data (USGS 2023) using three methods: the original quantitative fatty acid signature analysis model (Iverson et al. 2004, McKinney et al. 2017) and two alternative methods based on recommendations by Bromaghin et al. (2015c, 2016ab, 2017).