The Surprise Salmon
In Alaska, the fresh water that feeds the rivers is snowmelt from North America’s highest mountains and most active volcanoes. Time and again, they erupt and poison the rivers. Scientists have only just begun to piece together what might have happened nearly 2,000 years ago, when one race of salmon faced the death of their natal river and were forced back to the open ocean.
Expired: 01/01/70Video has closed captioning.