1. O PE N ACCE SS The 4th
International Whale Shark Conference, 16–18 May 2016, Doha, Qatar
Citethisarticleas:WomersleyFC,LeblondST,RowatDRL.Scarringinstanceandhealingcapabilities
of whale sharks and possible implications. QScience Proceedings (The 4th
International Whale
Shark Conference) 2016:iwsc4.67 http://dx.doi.org/10.5339/qproc.2016.iwsc4.67
http://dx.doi.org/10.5339/
qproc.2016.iwsc4.67
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1
Marine Conservation Society, Seychelles
*
Email: freyawomersley@gmail.com
Scarring instance and healing
capabilities of whale sharks and
possible implications
Freya C. Womersley1,*
, Savinien T. Leblond1
, David R.L. Rowat1
Background
With increasing levels of tourism and other anthropogenic activities around whale shark aggregations
globally there is an increased risk of physical damage to sharks from boat collisions. As such,
documenting the occurrence of injuries to sharks can be a useful method of recording the impacts
of tourism and other marine based activities as well as the effectiveness of management efforts. The
seasonal whale shark aggregation off Djibouti has seen an increase in both physical scarring and
tourism and is used here as a case study.
Approach
Scarring records and photos in the Djibouti whale shark database from 2009 to 2015 were reviewed
to establish instance and effects of injury on the viability of whale sharks. To calculate the level
of injury, in-water sighting data, which recorded scarring, were sorted into major or minor scar
categories after the methods of Speed et al. (2008). Major scars were classified as being potentially
life threatening and include fin amputation and lacerations penetrating the sub-dermal layer.
The probable origin of the scars was also attributed where possible. To avoid overestimation
of population scarring and to make results comparable across aggregations, minor scars (such
as abrasions, small bites and nicks) were omitted. To quantify medium-term effects of injury,
photographic evidence from returning whale sharks was reviewed to estimate healing rates. Healing
rates were obtained using the maximum number of years between observing a fresh injury and a fully
healed scar. A fully healed scar was defined as an injury with no non-skin/sub-dermal tissue visible.
Results
The incidence of major scarring recorded in the Djibouti aggregation varied during the study period
from a minimum of 15.6% in 2011 to 27.3% in 2015. Of these, 57.9% were attributable to boat strikes
in 2011 compared to 40% in 2015. Lacerations to fins showed the quickest healing rates. Sharks
observed with fresh lacerations to the first dorsal fin indicative of propeller strikes showed scar-
tissue growth on subsequent re-sighting and fully healed scars within a year. Lacerations to the
main body of the sharks showed healing rates of a maximum of two years. Amputations showed a
maximum healing time of one year but little capacity for tissue regeneration. However, one case of a
partially amputated first dorsal fin showed full re-growth of the fin after five years, an instance that is
exceptional and has not been recorded before.

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Womersley, Leblond, Rowat, QScience Proceedings 2016.iwsc4:67
Conclusion
When reviewing scar photos it is clear that whale sharks have the ability to tolerate major injuries
through their extraordinary regenerative capabilities. This suggests that whale sharks can recover
from boat strikes; however, sharks that did not survive strikes will not be re-recorded and would show
as a loss from the dataset. Similarly, the long-term hindrances to normal behavior that are caused
by major injuries remain largely unknown. The study reinforces the need for a series of regulations
including speed limits to be implemented and enforced within the study site, Arta Marine Protected
Area, Djibouti. This approach of recording scars can be applied to other shark populations to improve
understanding of shark healing capabilities and the species as a whole.
Keywords: Djibouti, scarring, healing, regeneration, ecotourism