Determining Age and Growth Through Bomb Radiocarbon Age Validation

Research with Otoliths.

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During the height of the Cold War in the late 1950s to early ‘60s, the United States, Russia, and other countries exploded many nuclear bombs above ground. These bombs significantly increased the amount of C-14 (also known as bomb-produced radiocarbon) in the atmosphere and in the surface layers of the ocean. Because C-14 has a half-life of 5,730 years, its presence remains in earth’s air and oceans for millenniums and the bomb-produced increase serves as a timestamp in fish otoliths.

How the Age Validation Method Works

Using bomb-produced radiocarbon to age fish requires a different biological organism which has a C-14 increase of known timing as a reference.

If we know the year a fish was collected and have estimated the fish’s age in the laboratory by counting otolith growth rings (that’s fish ageing), then we know when the otolith core was probably laid down. By comparing the probable timing and amount of C-14 there is in the otolith’s core to the known timing of the reference amount, we then learn if we counted the growth rings correctly.

Species for which this method has been applied include: Pacific ocean perch, Dover sole, yellowfin sole, northern rockfish, petrale sole, redstripe rockfish, harlequin rockfish, shortraker rockfish, shortspine thornyhead rockfish, Pacific halibut, longnose skate, and big skate. 

Bomb-Produced 14C Publications

 

Haltuch, M. A., Hamel O. S., Piner K. R., McDonald P., Kastelle C. R., and Field J. C.
2013. A California Current bomb radiocarbon reference chronology and petrale sole (Eopsetta jordani) age validation. Canadian Journal of Fisheries and Aquatic Sciences 70:22-31.

Helser, T. E., Kastelle C. R., and Lai H. L.
2014. Modeling environmental factors affecting assimilation of bomb-produced Δ14C in the North Pacific Ocean: implications for age validation studies. Ecological Modelling 277:108–118.

Kastelle, C. R., D. K. Kimura, and B. J. Goetz.
2008. Bomb radiocarbon age validation of Pacific ocean perch (Sebastes alutus) using new statistical methods.
Canadian Journal of Fisheries and Aquatic Sciences 65:1101-1112.

Kastelle, C. R., D. M. Anderl, D. K. Kimura, and C. G. Johnston.
2008. Age validation of Dover sole (Microstomus pacificus) by means of bomb radiocarbon. Fish. Bull., U.S. 106:375-385.

Kastelle, C., Helser T., TenBrink T., Hutchinson C., Goetz B., Gburski C., and Benson I.
2020. Age validation of four rockfishes (genera Sebastes and Sebastolobus) with bomb-produced radiocarbon. Marine and Freshwater Research doi.org/10.1071/MF19280

Kastelle, C. R., Helser T. E., Black B. A., Stuckey M. J., Gillespie D. C., McArthur J., Little D., Charles K. D., and Khan R. S.
2011. Bomb-produced radiocarbon validation of growth-increment crossdating allows marine paleoclimate reconstruction. Palaeogeogr Palaeoclimatol Palaeoecol 311:126-135.

Kastelle, C. R., Helser T. E., Wischniowski S. G., Loher T., Goetz B. J., and Kautzi L. A.
2016. Incorporation of bomb-produced 14C into fish otoliths: A novel approach for evaluating age validation and bias with an application to yellowfin sole and northern rockfish. Ecological Modelling 320:79-91.

King, J. R., Helser T., Gburski C., Ebert D. A., Cailliet G., and Kastelle C. R.
2017. Bomb radiocarbon analyses validate and inform age determination of longnose skate (Raja rhina) and big skate (Beringraja binoculata) in the north Pacific Ocean. Fisheries Research 193:195-206.

Wischniowski, S. G., Kastelle C. R., Loher T., and Helser T. E.
2015. Incorporation of bomb-produced C-14 into fish otoliths. An example of basin-specific rates from the North Pacific Ocean. Canadian Journal of Fisheries and Aquatic Sciences 72:879-892.