It’s always been a given that Native Alaskans have been fishing for thousands of years, but now a new study concludes the practice dates all the way back to the Ice Age, Alaska Dispatch News reports.

A study published this week in the Proceedings of the National Academy of Sciences found the earliest known evidence Ice Age humans in North America used salmon as a food source. Ancient DNA and stable isotope analysis from salmon vertebrae bones found in Interior Alaska indicate sea-run chum salmon were consumed by North American hunters 11,500 years ago.