AFSC/REFM: Bomb-produced age validation study

Fish age validation with bomb-produced radiocarbon (14C) requires a known-age Delta14C reference chronology
spanning the era of a marine increase in bomb-produced 14C (1950s to 1960s). Concordance between otolith Delta14C
in a validation sample and the reference chronology indicates accurate test ages. Here we compare a new Delta14C
reference chronology from the eastern Bering Sea and a previously established reference from the Gulf of Alaska
with otolith Delta14C in two validation species, eastern Bering Sea yellowfin sole (Limanda aspera)
and Gulf of Alaska northern rockfish (Sebastes polyspinis). Our goals were twofold: to validate
the age determination methods for northern rockfish and yellowfin sole using comparisons within oceanic basins,
and to explore the outcome of making naive comparisons of these validation data sets to reference chronologies
across oceanic basins. We present a information-theoretic approach to hypothesis testing and
use Bayesian data analysis with Markov Chain Monte Carlo simulation as a probabilistic framework
to quantitatively estimate age determination bias and its uncertainty. Based on within-basin comparisons
we concluded that estimated ages for eastern Bering Sea yellowfin sole and Gulf of Alaska northern rockfish
were accurate. We further concluded that there were important differences in otolith 14C uptake between fish
from the two ocean basins.