Bomb radiocarbon age validation of Pacific ocean perch (Sebastes alutus) using new statistical methods

Abstract

We used bomb-produced radiocarbon (14C) to validate ages of Pacific ocean perch ( Sebastes alutus ), which are routinely estimated with the cut-and-burn method at the Alaska Fisheries Science Center (Seattle, Washington, USA). New statistical methods to compare Δ14C in validation samples with a reference chronology are introduced: (i) calculating confidence intervals around the LOESS-smoothed Δ14C reference chronology using simultaneous inference; (ii) purposely adding biases to the validation sample ages and then analyzing the sum of squared residuals of the validation samples’ Δ14C about the LOESS-smoothed reference chronology; and (iii) standardizing the Δ14C measurements from the validation sample to better fit the reference chronology. Standardized Δ14C measurements are particularly useful when researchers suspect that environmental and biological differences between the validation samples and the reference chronology may exist that affect the level, but not the timing, of Δ14C in the samples. These new methods can be applied simultaneously. Two previous bomb radiocarbon studies on canary rockfish ( Sebastes pinniger ) and black drum ( Pogonias cromis ) were reanalyzed, further illustrating the usefulness of these new methods.