Salmon fishing in North America dates from the end of the last ice age, a new study reports.

In a cooking hearth at the Upward Sun River archaeological site in central Alaska, researchers discovered salmon remains that are 11,500 years old. The hearth sits atop a grave in which two infants were buried.

The remains are the earliest confirmed evidence of salmon consumption in North America, the researchers said.

“Before this, we really had no idea that Paleo-Indians were using salmon or fish of any kind,” said Carrin Halffman, an archaeologist at the University of Alaska Fairbanks and an author of the report. “Sites had been dominated by bones of other animals.”

The study appears in the current issue of Proceedings of the National Academy of Sciences.

Although about 300 bone fragments belonging to salmon were found, the site represents the beginning of salmon exploitation, said Ben Potter, also an archaeologist at the University of Alaska Fairbanks and a study author.