Further evidence of pigmentation change in white sharks, Carcharodon carcharias
Rachel Robbins A B and Andrew Fox AA Fox Shark Research Foundation, Adelaide, SA 5070, Australia.
B Corresponding author. Email: rachel@sharkfoundation.com
Marine and Freshwater Research 63(12) 1215-1217 https://doi.org/10.1071/MF12208
Submitted: 1 August 2012 Accepted: 22 September 2012 Published: 12 December 2012
Abstract
Patterns of pigmentation are widely used for the identification of white sharks, with photographic databases often forming the basis for studies of population modelling, site fidelity and movement patterns. The permanence of these identifying markings is assumed to remain constant. Here, we present evidence of melanism resulting in a change in the shape and size of pigmentation markings on the lower caudal lobe of a female white shark. We found a 33% reduction in size of an islet over a 9-month period. The newly melanised region was 10% darker than the adjoining pigmented areas, and did not match the original pattern. Possible causes of the observed melanism are presented, and the implications for the reliability of using caudal-fin pigmentation patterns for identification purposes are discussed, with a combinational matching approach recommended.
Additional keywords : great white shark, markings, melanin, photographic ID.
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