Use of the bomb radiocarbon chronometer for age validation in the blue grenadier Macruronus novaezelandiae

J. M. Kalish, J. M. Johnston, D. C. Smith, A. K. Morison, S. G. Robertson

Research output: Contribution to journalArticlepeer-review

29 Scopus citations

Abstract

Accelerator mass-spectrometry was used to measure radiocarbon in the earliest formed portions of selected blue grenadier. Macruronus novaezelandiae, otoliths to provide a validation of fish-age estimates based on the quantification of opaque and translucent zones in otolith thin-sections. Δ14C data from blue grenadier otoliths were compared with previous estimates of Δ14C in seawater-dissolved inorganic carbon at similar latitudes, longitudes, and depths to link variation in otolith Δ14C to time. Minimum otolith Δ14C was -76.9 ± 7.7‰, indicative of pre-bomb radiocarbon levels below the surface mixed-layer at latitudes where juvenile blue grenadier are found. When plotted versus fish age estimated from otolith sections, the majority of the Δ14C data combined to define a curve reflecting the increase in bomb radiocarbon in temperate oceans of the Southern Hemisphere, indicating that age-estimation procedures based on otolith thin-sections are satisfactory for determining blue grenadier age. If otolith-section age estimates were correct, peak otolith Δ14C of 106.8 ± 7.9‰ occurred during the late 1960s, i.e. earlier than expected. This may be a manifestation of an increase in the mixed-layer depth associated with increased frequency of zonal westerly winds at this time.

Original languageEnglish
Pages (from-to)557-563
Number of pages7
JournalMarine Biology
Volume128
Issue number4
DOIs
StatePublished - Jun 1997
Externally publishedYes

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