Skip to main content

Scarring patterns and relative mortality rates of Indian Ocean whale sharks

Buy Article:

$51.00 plus tax (Refund Policy)

This study recorded the scarring rate and severity for whale sharks Rhincodon typus from three Indian Ocean aggregations (Australia, Seychelles and Mozambique), and examined whether scarring (mostly attributed to boat strikes and predator attacks) influences apparent survival rates using photo-identification libraries. Identifications were based on spot-and-stripe patterns that are unique to individual whale sharks. Scarring was most prevalent in the Seychelles aggregation (67% of individuals). Predator bites were the most frequent source of scarring (aside from minor nicks and abrasions) and 27% of individuals had scars consistent with predator attacks. A similar proportion of whale sharks had blunt trauma, laceration and amputation scars, the majority of which appeared to be caused by ship collisions. Predator bites were more common (44% of individuals) and scars from ship collisions were less common at Ningaloo Reef than at the other two locations (probability of among-site differences occurring randomly = 0·0007 based on a randomized multinomial contingency analysis). In all aggregations, scars occurred most often on the caudal fin, which may result from the fin being the body part closest to the surface when boats pass over, or they may provide a large target for predator attack. No evidence was found for an effect of scarring on apparent survival (; mean ±s.e.) for the Ningaloo (not scarred = 0·858 ± 0·033; scarred = 0·929 ± 0·033) or Seychelles populations (not scarred = 0·502 ± 0·060; scarred = 0·538 ± 0·070). The lower apparent survival of the Seychelles population may be attributed to a high number of transient whale sharks in this aggregation that might bias estimates. This study indicates that while scarring from natural predators and smaller vessels appears to be unrelated to whale shark survival, the effect of deaths related to ship strike need to be quantified to assist in future management of this species.
No References
No Citations
No Supplementary Data
No Data/Media
No Metrics

Keywords: Rhincodon typus; boat strike; mark–recapture; photo-identification; scarring; survival rates

Document Type: Regular Paper

Affiliations: 1: Australian Institute of Marine Science, P. O. Box 40197, Casuarina MC, Northern Territory 0811, Australia 2: Marine Conservation Society, Seychelles, P. O. Box 1299, Victoria, Mahe, Seychelles 3: Manta Ray and Whale Shark Research Centre, Tofu Beach, Mozambique

Publication date: 2008-04-01

  • Access Key
  • Free content
  • Partial Free content
  • New content
  • Open access content
  • Partial Open access content
  • Subscribed content
  • Partial Subscribed content
  • Free trial content
Cookie Policy
Cookie Policy
Ingenta Connect website makes use of cookies so as to keep track of data that you have filled in. I am Happy with this Find out more