Skip to main content
Article
Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives
Marine & Freshwater Research
  • Cameron T Perry, Nova Southeastern University
  • Joana Figueiredo, Nova Southeastern University
  • Jeremy Vaudo, Nova Southeastern University
  • James Hancock, Maldives Whale Shark Research Programme
  • Richard Rees, Maldives Whale Shark Research Programme
  • Mahmood S Shivji, Nova Southeastern University
Document Type
Article
Publication Date
7-9-2018
Keywords
  • age estimation,
  • age and growth,
  • elasmobranch,
  • growth rates,
  • laser photogrammetry,
  • von Bertalanffy
Disciplines
Abstract

Whale sharks (Rhincodon typus) are an endangered species whose growth and reproductive biology are poorly understood. Given their conservation concern, estimating growth parameters, as traditionally derived from vertebral samples of dead animals, is challenging. We used a non-invasive approach to investigate growth parameters of whale sharks frequenting the South Ari Atoll, Maldives, by analysing repeat measurements of free-swimming sharks over a 10-year period. Total lengths of the sharks were estimated by three measurement methods. Visual estimates underestimated the sizes of large sharks, whereas laser and tape measurements yielded results that were similar to one another. The Maldives aggregation consisted of primarily male (91%) juvenile (total length = 3.16–8.00 m) sharks and sharks new to the area were significantly smaller than were returning sharks, which suggests that this site may constitute a secondary nursery ground. Estimates of von Bertalanffy (VBG) growth parameters for combined sexes (L∞ = 19.6 m, k = 0.021 year–1) were calculated from 186 encounters with 44 sharks. For males, VBG parameters (L∞ = 18.1 m, k = 0.023 year–1) were calculated from 177 encounters with 40 sharks and correspond to a male age at maturity of ~25 years and longevity of ~130 years. Differences between these estimates and those from other studies underscore the need for regional studies.

ORCID ID
0000-0001-5254-581X
DOI
10.1071/MF17393
Citation Information
Cameron T Perry, Joana Figueiredo, Jeremy Vaudo, James Hancock, et al.. "Comparing length-measurement methods and estimating growth parameters of free-swimming whale sharks (Rhincodon typus) near the South Ari Atoll, Maldives" Marine & Freshwater Research Iss. MF17393 (2018) p. A - I ISSN: 1323-1650
Available at: http://works.bepress.com/jeremy-vaudo/32/