C05_03

In light of Marine20 – how old is the Greenland shark?

Olsen J¹, Nielsen J², Grønkjær P¹, Steffensen J³

¹Aarhus University, Aarhus, Denmark, ²Greenland Institute of Natural Resources, Nuuk, Greenland, ³University of Copenhangen, Copenhagen, Denmark

In 2016 the longevity of the Greenland shark (Somniosus microcephalus) was determined to 392 ±120 years using radiocarbon analysis of eye lenses of 28 specimens. The age of pre-bomb sharks was determined using the Marine13 radiocarbon calibration curve with the assumption that the carbon source of the eye lens nucleus reflects food webs of potentially different ΔR levels. The common wisdom is that because both the absolute reservoir age R and the regional reservoir ages ΔR are changed with Marine20, then the calibrated ages are more or less unchanged. Nonetheless, what happens when you a Bayesian model with greatly increased error margins?  Here we present an updated age estimate of the longevity of the Greenland shark using Marine20 with updated ΔR values by employing a Bayesian model. Further constrains are added by radiocarbon dating of new specimens from the bomb curve era. To support the new post-bomb eye lens radiocarbon data, a marine reference dataset will be presented based on enamel radiocarbon dating of know-age 29 hooded seals (Cystophora cristata) from West Greenland.