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.

The purpose of this data set is to use bomb-produced 14C to confirm the accuracy of northern rockfish and yellowfin sole ages estimated from otolith growth-zones.

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There are no legal restrictions on access to the data. They reside in public domain and can be freely distributed.

User must read and fully comprehend the metadata prior to use. Applications or inferences derived from the data should be carefully considered for accuracy. Acknowledgement

of NOAA/NMFS/AFSC, as the source from which these data were obtained in any publications and/or other representations of these, data is suggested.

Excel

Data from RACE is proofed by normal protocols routinely used on survey data. Data generated by the Age and Growth program data (age estimates and associated codes) is proofed for typing errors, tested for precision with a 20% replicate, and accuracy is evaluated in comparisons of fish size vs. age.

The Final ages were evaluated for error by the Age (confirmation by reader A or L). Radiocarbon values are checked for accuracy by comparing two different sets of calculations, one by WOHI, NAOAMS, and one by Craig Kastelle at AFSC.

There were no samples from 1997 to 2003.

spot checked

Data from RACE is proofed by normal protocols routinely used on survey data. Data generated by the Age and Growth program data (age estimates and associated codes) is proofed for typing errors, tested for precision with a 20% replicate, and accuracy is evaluated in comparisons of fish size vs. age. The Final ages were evaluated for error by the Age (confirmation by reader A or L). Radiocarbon values are checked for accuracy by comparing two different sets of calculations, one by WOHI, NAOAMS, and one by Craig Kastelle at AFSC.

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