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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 (φ; mean ±s.e.) for the Ningaloo (not scarred φ= 0·858 ± 0·033; scarred φ= 0·929 ± 0·033) or Seychelles populations (not scarred φ= 0·502 ± 0·060; scarred φ= 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 shi

Background Effective approaches for the management and conservation of wildlife populations require a sound knowledge of population demographics, and this is often only possible through mark-recapture studies. We applied an automated spot-recognition program (I3S) for matching natural markings of wildlife that is based on a novel information-theoretic approach to incorporate matching uncertainty. Using a photo-identification database of whale sharks (Rhincodon typus) as an example case, the information criterion (IC) algorithm we developed resulted in a parsimonious ranking of potential matches of individuals in an image library. Automated matches were compared to manual-matching results to test the performance of the software and algorithm. Results Validation of matched and non-matched images provided a threshold IC weight (approximately 0.2) below which match certainty was not assured. Most images tested were assigned correctly; however, scores for the by-eye comparison were lower than expected, possibly due to the low sample size. The effect of increasing horizontal angle of sharks in images reduced matching likelihood considerably. There was a negative linear relationship between the number of matching spot pairs and matching score, but this relationship disappeared when using the IC algorithm. Conclusion The software and use of easily applied information-theoretic scores of match parsimony provide a reliable and freely available method for individual identification of wildlife, with wide applications and the potential to improve mark-recapture studies without resorting to invasive marking techniques.