Vertebral bomb radiocarbon suggests extreme longevity in white sharks - PubMed (original) (raw)

Vertebral bomb radiocarbon suggests extreme longevity in white sharks

Li Ling Hamady et al. PLoS One. 2014.

Abstract

Conservation and management efforts for white sharks (Carcharodon carcharias) remain hampered by a lack of basic demographic information including age and growth rates. Sharks are typically aged by counting growth bands sequentially deposited in their vertebrae, but the assumption of annual deposition of these band pairs requires testing. We compared radiocarbon (Δ(14)C) values in vertebrae from four female and four male white sharks from the northwestern Atlantic Ocean (NWA) with reference chronologies documenting the marine uptake of (14)C produced by atmospheric testing of thermonuclear devices to generate the first radiocarbon age estimates for adult white sharks. Age estimates were up to 40 years old for the largest female (fork length [FL]: 526 cm) and 73 years old for the largest male (FL: 493 cm). Our results dramatically extend the maximum age and longevity of white sharks compared to earlier studies, hint at possible sexual dimorphism in growth rates, and raise concerns that white shark populations are considerably more sensitive to human-induced mortality than previously thought.

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Conflict of interest statement

Competing Interests: The authors have declared that no competing interests exist.

Figures

Figure 1

Figure 1. Photomicrographs of sectioned vertebrae.

A) Upper section of vertebra taken from WS105. B) WS 100 vertebra; first dot is the birth band. Visible band pairs are marked by dots on the corpus calcareum. The lines indicate the vertebral radius (16.6 mm). Vertebral radius is measured at the angle of the vertebra where the intermedialia meets the corpus calcareum.

Figure 2

Figure 2. White shark Δ14C results compared to three Δ14C reference chronologies , , .

Results from male (A, B) and female (C, D) white shark vertebrae. Dotted line is porbeagle data smoothed with a Loess curve. For panels B and D, the arrows indicates the vertebral Δ14C curves that had to be shifted to line up with the reference chronologies (white open symbols are initial data, black symbols are data shifted to align with the references).

Figure 3

Figure 3. δ13C values for individual sharks.

Plotted by A) deposition year and B) age as corrected to fit the Δ14C reference curves.

Figure 4

Figure 4. Bivariate plot of δ13C versus Δ14C for individual sharks.

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References

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Grants and funding

This study was funded by the National Science Foundation (OCE 0825148 was awarded to SRT) and LLH was supported by the National Science Foundation Graduate Research Fellowship Program. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

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