Core testing was left to colleagues at Western Washington University like Andy Bunn (“Dare we say that's his core area of research,” Quinn says). The WWU team analyzed the cores from trees that were at least 40 years old. Their goal: to compare growth rates year-over-year between the 20 years covered by Quinn's study period, and rates during the two decades prior to that, in which salmon carcasses were deposited equally between both banks.