NEWPORT, Ore. – Dynamic and changing Arctic Ocean conditions likely caused three major mortality events in the eastern North Pacific gray whale population since the 1980s, a new study has found. During each of these die-offs, including one that began in 2019 and is ongoing, the gray whale population was reduced by up to 25% over just a few years, said Joshua Stewart, an assistant professor with Oregon State University’s Marine Mammal Institute and the study’s lead author.