Éditeur(s) : HAL CCSD
Résumé : International audience
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. Cite as: Chin A, Mourier J, Rummer JL (2015) Blacktip reef sharks (Carcharhinus melanopterus) show high capacity for wound healing and recovery following injury. Conserv Physiol 3: doi:10.1093/conphys/cov062.
Conservation physiology

Droits : http://creativecommons.org/licenses/by/
hal-01250745
https://hal-univ-perp.archives-ouvertes.fr/hal-01250745
https://hal-univ-perp.archives-ouvertes.fr/hal-01250745/document
https://hal-univ-perp.archives-ouvertes.fr/hal-01250745/file/Conserv%20Physiol-2015-Chin-.pdf
DOI : 10.1093/conphys/cov062

Éditeur(s) : HAL CCSD Oldendorf/Luhe
Résumé : International audience
Unmanned aerial vehicles (UAVs) are being increasingly used in studies of marinefauna. Here, we tested the use of a UAV (DJI Phantom II®) to assess fine-scale variation in densitiesof 2 elasmobranchs (blacktip reef sharks Carcharhinus melanopterus and pink whiprays Himanturafai) on reef systems off Moorea (French Polynesia). We flew parallel transects designed to samplereef habitats (fringing, channel and sandflat habitats) across 2 survey blocks. Block 1 included ashark and ray provisioning site with potentially higher elasmobranch densities, whereas Block 2most likely had lower densities with no provisioning activities. Across 10 survey days in July 2014,we flew 3 transects (400 m) within each survey block (n = 60 total transect passes). As expected,densities (animals ha−1) were significantly higher in Block 1 than in Block 2, particularly where provisioningactivities occur. Differences between habitats surveyed were also found. Our study providesthe first direct estimates of shark and ray densities in coral-reef ecosystems and demonstratesthat UAVs can produce important fishery-independent data for elasmobranchs, particularly inshallow-water habitats.
ISSN: 0171-8630

hal-01416757
https://hal-univ-perp.archives-ouvertes.fr/hal-01416757
DOI : 10.3354/meps11945

Éditeur(s) : HAL CCSD Royal Society, The
Résumé : International audience
Individuals can play different roles in maintaining connectivity and socialcohesion in animal populations and thereby influence population robustnessto perturbations.We performed a social network analysis in a reef shark populationto assess the vulnerability of the global network to node removal underdifferent scenarios. We found that the network was generally robust to theremoval of nodes with high centrality. The network appeared also highlyrobust to experimental fishing. Individual shark catchability decreased as afunction of experience, as revealed by comparing capture frequency and sitepresence. Altogether, these features suggest that individuals learnt to avoidcapture, which ultimately increased network robustness to experimentalcatch-and-release. Our results also suggest that some caution must be takenwhen using capture–recapture models often used to assess population sizeas assumptions (such as equal probabilities of capture and recapture) maybe violated by individual learning to escape recapture.
EISSN: 1471-2954

hal-01561754
https://hal-univ-perp.archives-ouvertes.fr/hal-01561754
DOI : 10.1098/rsbl.2016.0824