Abstract
Wound healing is important for sharks from the earliest life stages, for example, as the 'umbilical scar' in viviparous species heals, and throughout adulthood, when sharks can incur a range of external injuries from natural and anthropogenic sources. Despite anecdotal accounts of rapid healing in elasmobranchs, data regarding recovery and survival of individuals from different wound or injury types has not been systematically collected. The present study documented: (i) 'umbilical scar' healing in wild-caught, neonatal blacktip reef sharks while being reared for 30 days in flow-through laboratory aquaria in French Polynesia; (ii) survival and recovery of free-swimming blacktip reef sharks in Australia and French Polynesia following a range of injuries; and (iii) long-term survival following suspected shark-finning activities. Laboratory monitoring, tag-recapture records, telemetry data and photo-identification records suggest that blacktip reef sharks have a high capacity to survive and recover from small or even large and severe wounds. Healing rates, recovery and survival are important factors to consider when assessing impacts of habitat degradation and fishing stress on shark populations. The present study suggests that individual survival may depend more on handling practices and physiological stress rather than the extent of physical injury. These observations also contribute to discussions regarding the ethics of tagging practices used in elasmobranch research and provide baseline healing rates that may increase the accuracy in estimating reproductive timing inferred from mating scars and birth dates for neonatal sharks based on umbilical scar healing status.
Highlights
Sharks and rays incur injuries throughout all life stages that originate from many sources, including mating and courtship behaviours, parturition, aggression, predation and human activities (Carrier et al, 1994; Towner et al, 2012; Hoyos-Padilla et al, 2013)
The present study suggests that individual survival may depend more on handling practices and physiological stress rather than the extent of physical injury. These observations contribute to discussions regarding the ethics of tagging practices used in elasmobranch research and provide baseline healing rates that may increase the accuracy in estimating reproductive timing inferred from mating scars and birth dates for neonatal sharks based on umbilical scar healing status
Polynesia and Australia, and data suggest that this species has a high capacity to recover from wounds and survive injuries
Summary
Sharks and rays incur injuries throughout all life stages that originate from many sources, including mating and courtship behaviours, parturition (for females and neonates), aggression, predation and human activities (Carrier et al, 1994; Towner et al, 2012; Hoyos-Padilla et al, 2013). Large sharks have exhibited recovery from penetrative harpoon wounds (Riley et al, 2009) and abrasion caused by marine debris With the exception of anecdotal evidence, there are relatively few records that document healing and recovery from the range of wounds experienced by sharks. Such information is important to the welfare of individuals and sustainability of populations, but mating and umbilical scars, for example, can be used to indicate timing of reproduction in elasmobranchs (Walker, 2005). There are few explicit accounts of healing rates and survival after internal insertion of acoustic tags to inform this discussion
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