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Scarring patterns and relative mortality rates of Indian Ocean whale sharks

Speed, Conrad Wayne, Meekan, Mark G., Rowat, David, Pierce, S., Marshall, A. and Bradshaw, Corey J. A. (2008). Scarring patterns and relative mortality rates of Indian Ocean whale sharks. Journal of Fish Biology,72(6):1488-1503.

Document type: Journal Article
Citation counts: Altmetric Score Altmetric Score is 18
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IRMA ID A00006xPUB11
Title Scarring patterns and relative mortality rates of Indian Ocean whale sharks
Author Speed, Conrad Wayne
Meekan, Mark G.
Rowat, David
Pierce, S.
Marshall, A.
Bradshaw, Corey J. A.
Journal Name Journal of Fish Biology
Publication Date 2008
Volume Number 72
Issue Number 6
ISSN 0022-1112   (check CDU catalogue open catalogue search in new window)
Start Page 1488
End Page 1503
Total Pages 16
Place of Publication U.K.
Publisher Wiley-Blackwell Publishing
Field of Research 0602 - Ecology
0608 - Zoology
0704 - Fisheries Sciences
HERDC Category C1 - Journal Article (DEST)
Abstract 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 ship strike need to be quantified to assist in future management of this species.
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Created: Fri, 01 May 2009, 13:26:54 CST by Sarena Wegener