Ageing white sharks

White sharks (Carcharodon carcharias) are wide-ranging throughout most of New Zealand (NZ), but the life history parameters for NZ white sharks are not well defined. In a preliminary study, NIWA scientists used standard X-ray and micro-CT imaging techniques to estimate age and growth from vertebral banding patterns for NZ white sharks for the first time. Nearly half of the individuals were young (1–2 years old) and only six sharks were estimated to be older than 10 years of age. Results suggest that NZ white sharks are relatively fast growing initially and possibly long-lived, with a near linear relationship between length and growth for young New Zealand white sharks. This project was funded by the Department of Conservation’s Conservation Services Programme (CSP) project POP2021-05. We thank Jaret Bilewitch (NIWA), Dane Gerneke (University of Auckland), and Egon Perilli and Sophie Rapagna (Flinders University) for their contributions to this work. We thank Clinton Duffy (DOC) for providing white shark vertebrae samples.

Can you help us age this white shark?

We asked participants at the 7th International Otolith Symposium 2023, in Viña del Mar Chile, to attempt to age a white shark vertebrae using a video reconstruction and micro-CT animation.

Results from the 7th International Otolith Symposium

Kia ora and Hello from Aotearoa/New Zealand.

Firstly, thanks to everyone at the recent otolith symposium in Chile who tried to age our white shark via the animation. Your results are below, in random order:

See below the pixel intensity plot with putative band counts overlaid, from the corresponding “Standard X-ray process” along a corpus calcareum for this specimen which was a 4.7m female. Considering all the feedback, we determine the age as 14, there being 13 reasonably clear annual rings plus a ring forming at the edge.

Thanks again from all of us here at NIWA,

Brit, Caoimhghin and Tom.