Fish Trap Dating Back 11,000 Years in Alaska Reveals Migration Secrets

The discovery of the oldest stone fish weir in history, from 11,000 years ago, has been confirmed in Alaska.

A team of scientists from both robotics company Sunfish Inc. and Sealaska Heritage Institute discovered the weir in Shakan Bay on the west side of Prince of Wales Island. The weir was first detected using sonar in 2010 but has now been confirmed as being a fish trap.

Other stone weirs have been discovered around southeast Alaska, but this marks the oldest one ever found, and the first to be confirmed underwater in North America.

Fish weirs were used to capture fish, using low arched walls made of boulders or wooden posts. During high tide, the fish would swim over the walls, becoming trapped as the tide receded. This was one of the hunting techniques used by the first humans to have entered America after Paleolithic hunter-gatherers entered North America from the North Asian Mammoth steppe via the Beringia land bridge.

alaskan fish weir
This image comes from an ROV of the weir, which is comprised of semi-circular stacked stones on the seafloor. The existence of the 11,000-year-old weir means that humans crossed over to North America from Asia 1,100 years earlier than thought. Screencap of video from Dr. Kelly Monteleone, Our Submerged Past.

"We established the date of the weir based on our current sea level reconstruction. The weir only functions when it is intertidal, and our current reconstruction of sea level changes has the depth as intertidal approximately 11,100 years ago," Kelly Monteleone, one of the researchers and an archaeologist at the University of Calgary, told Newsweek.

"Identification of the weir on the continental shelf also confirms that archaeological sites are preserved in this submerged environment," she said.

According to ThoughtCo, previous to this discovery, the oldest fish weir found was the Sebasticook Fish Weir in central Maine, where a wooden stake was radiocarbon dated and found to be around 5,770 years old. Others in southeastern Alaska date to around 3,000 years ago.

"The entire vessel was bouncing with excitement when we realized it was indeed a weir," Monteleone said in a statement."Personally, I felt relief after a decade of saying this was a weir. Finally confirming the location was satisfying and exhilarating."

This discovery is significant because it was previously thought that humans only crossed over from Asia into the Americas around 10,000 years ago, based on DNA testing on the ancient remains of a young Native man. The discovery of the weir and its age means that we arrived around 1,100 years earlier than first thought.

Native occupancy may, in fact, have been much older than that, as it would have taken time for people to understand their environment and to engineer ways to catch fish for survival.

"The extrapolated 11,100-year date is actually quite late," Monteleone said in the statement. "I anticipate we will find evidence in Southeast Alaska that dates it to at least 16,000 years ago."