117 research outputs found
Contribution of Forensic Analysis to Shark Profiling Following Fatal Attacks on Humans
Size assessment and species identification are paramount after a fatal attack for profiling a ‘problem-animal’ that could be specifically eliminated. In addition to ecological and behavioural data about candidate species, forensic analysis can provide critical information for achieving this goal. After providing basic information about fatal attacks and the anatomical features of the three species (white shark, tiger shark and bull shark) that are responsible for >80% of lethal interactions, this chapter presents the most used tools for assessing the species and size of a potential attacker. The size assessment can be done through measurements (on the body of the victim or from good-quality photographs) of the bite width (BW) and bite circumference (BC); the size is then obtained from regressions from the literature between BW/BC and total length. The average interdental distance (IDD) is also used through a similar process. Finally, other details of the wounds, such as the shape of the bite margin or of flesh flaps that directly depend on the jaw characteristics, can also be used to contribute to the final assessment. Although important, a forensic analysis should be complemented by data on shark ecology and behaviour for a more reliable conclusion
Reef-fidelity and migration of tiger sharks, Galeocerdo cuvier, across the Coral Sea
© The Author(s), 2014. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in PLoS One 9 (2014): e83249, doi:10.1371/journal.pone.0083249.Knowledge of the habitat use and migration patterns of large sharks is important for assessing the effectiveness of large predator Marine Protected Areas (MPAs), vulnerability to fisheries and environmental influences, and management of shark–human interactions. Here we compare movement, reef-fidelity, and ocean migration for tiger sharks, Galeocerdo cuvier, across the Coral Sea, with an emphasis on New Caledonia. Thirty-three tiger sharks (1.54 to 3.9 m total length) were tagged with passive acoustic transmitters and their localised movements monitored on receiver arrays in New Caledonia, the Chesterfield and Lord Howe Islands in the Coral Sea, and the east coast of Queensland, Australia. Satellite tags were also used to determine habitat use and movements among habitats across the Coral Sea. Sub-adults and one male adult tiger shark displayed year-round residency in the Chesterfields with two females tagged in the Chesterfields and detected on the Great Barrier Reef, Australia, after 591 and 842 days respectively. In coastal barrier reefs, tiger sharks were transient at acoustic arrays and each individual demonstrated a unique pattern of occurrence. From 2009 to 2013, fourteen sharks with satellite and acoustic tags undertook wide-ranging movements up to 1114 km across the Coral Sea with eight detected back on acoustic arrays up to 405 days after being tagged. Tiger sharks dove 1136 m and utilised three-dimensional activity spaces averaged at 2360 km3. The Chesterfield Islands appear to be important habitat for sub-adults and adult male tiger sharks. Management strategies need to consider the wide-ranging movements of large (sub-adult and adult) male and female tiger sharks at the individual level, whereas fidelity to specific coastal reefs may be consistent across groups of individuals. Coastal barrier reef MPAs, however, only afford brief protection for large tiger sharks, therefore determining the importance of other oceanic Coral Sea reefs should be a priority for future research.Funding was provided by the the Agence Francaise de Développement (http://www.afd.fr), French Pacific Fund, the CRISP program (www.crisponline.info) and QLD Fisheries
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Effects of Mpa on Small Scale Coral Reef Fisheries and Communities: Evidence From Vanuatu (South Pacific)
If the role of MPAs as a conservation tool is now widely demonstrated
even with some variability, their effects on fishery yields, tourism revenues
and social aspects are only confirmed by very few studies. More than 550
MPA now exist in the South Pacific mostly community based managedand
the expectations on their ecological and socio-economic effects are
high. A study based on a control-impact approach has been conducted in
Vanuatu (South Pacific) to evaluate the effects of MPA for the local and
global community. 3 sites with well established MPAs and their respective
control sites have been selected with a similar ecological habitat but with
different fishing pressure, tourism development and level of subsistence
economy. The most direct effects of MPA on the coral reef fisheries cpue
and yields and on the site attractiveness for the tourism industry have been
assessed. Other impacts on the social capital bridging and bonding- and
governance of local communities were identified too. At a different scale,
the benefits in the form of avoided cost for government as well as the
attributes of world heritage conservation were considered. Most of these
effects were quantified from observed data and as far as possible valued
with a bio-economic approach with a special focus on the fishery
assessment. The results showed variability in the outcomes between the
sites. Some of them present small quantifiable benefits on fishery or
tourism and reveal an imbalance between local and global beneficiaries,
questioning the future of the MPA. The limits of the western economic
approach in the Melanesian cultural context were outlined.Keywords: Economics and Marine Conservation, Fisheries Economics, Fishery ManagementKeywords: Economics and Marine Conservation, Fisheries Economics, Fishery Managemen
Length-Based Assessment of an Artisanal Albulid Fishery in the South Pacific: a Data-Limited Approach for Management and Conservation
Data-limited fisheries assessment methods have great potential to help inform small island communi
Insights Into Insular Isolation of the Bull Shark, Carcharhinus leucas (Müller and Henle, 1839), in Fijian Waters
The bull shark (Carcharhinus leucas) is a large, mobile, circumglobally distributed high trophic level predator that inhabits a variety of remote islands and continental coastal habitats, including freshwater environments. Here, we hypothesize that the barriers to dispersal created by large oceanic expanses and deep-water trenches result in a heterogeneous distribution of the neutral genetic diversity between island bull shark populations compared to populations sampled in continental locations connected through continuous coastlines of continental shelves. We analyzed 1,494 high-quality neutral single nucleotide polymorphism (SNP) markers in 215 individual bull sharks from widespread locations across the Indian and Pacific Oceans (South Africa, Indonesia, Western Australia, Papua New Guinea, eastern Australia, New Caledonia, and Fiji). Genomic analyses revealed partitioning between remote insular and continental populations, with the Fiji population being genetically different from all other locations sampled (FST = 0.034–0.044, P \u3c 0.001), and New Caledonia showing marginal isolation (FST = 0.016–0.024, P \u3c 0.001; albeit based on a small sample size) from most sampled sites. Discriminant analysis of principal components (DAPC) identified samples from Fiji as a distinct cluster with all other sites clustering together. Genetic structure analyses (Admixture, fastStructure and AssignPOP) further supported the genetic isolation of bull sharks from Fiji, with the analyses in agreement. The observed differentiation in bull sharks from Fiji makes this site of special interest, as it indicates a lack of migration through dispersal across deep-water trenches and large ocean expanses
Convergence of marine megafauna movement patterns in coastal and open oceans
Author Posting. © The Author(s), 2017. This is the author's version of the work. It is posted here for personal use, not for redistribution. The definitive version was published in Proceedings of the National Academy of Sciences of the United States of America 115 (2018): 3072-3077, doi:10.1073/pnas.1716137115.The extent of increasing anthropogenic impacts on large marine
vertebrates partly depends on the animals’ movement patterns.
Effective conservation requires identification of the key drivers of
movement including intrinsic properties and extrinsic constraints
associated with the dynamic nature of the environments the animals
inhabit. However, the relative importance of intrinsic versus
extrinsic factors remains elusive. We analyse a global dataset of
2.8 million locations from > 2,600 tracked individuals across 50
marine vertebrates evolutionarily separated by millions of years
and using different locomotion modes (fly, swim, walk/paddle).
Strikingly, movement patterns show a remarkable convergence,
being strongly conserved across species and independent of body
length and mass, despite these traits ranging over 10 orders of
magnitude among the species studied. This represents a fundamental
difference between marine and terrestrial vertebrates not
previously identified, likely linked to the reduced costs of locomotion
in water. Movement patterns were primarily explained by the
interaction between species-specific traits and the habitat(s) they
move through, resulting in complex movement patterns when
moving close to coasts compared to more predictable patterns
when moving in open oceans. This distinct difference may be
associated with greater complexity within coastal micro-habitats,
highlighting a critical role of preferred habitat in shaping marine
vertebrate global movements. Efforts to develop understanding
of the characteristics of vertebrate movement should consider the
habitat(s) through which they move to identify how movement
patterns will alter with forecasted severe ocean changes, such as
reduced Arctic sea ice cover, sea level rise and declining oxygen
content.Workshops funding granted by the UWA Oceans Institute, AIMS, and
KAUST. AMMS was supported by an ARC Grant DE170100841 and an IOMRC
(UWA, AIMS, CSIRO) fellowship; JPR by MEDC (FPU program, Spain); DWS by
UK NERC and Save Our Seas Foundation; NQ by FCT (Portugal); MMCM by
a CAPES fellowship (Ministry of Education)
Global Spatial Risk Assessment of Sharks Under the Footprint of Fisheries
Effective ocean management and conservation of highly migratory species depends on resolving overlap between animal movements and distributions and fishing effort. Yet, this information is lacking at a global scale. Here we show, using a big-data approach combining satellite-tracked movements of pelagic sharks and global fishing fleets, that 24% of the mean monthly space used by sharks falls under the footprint of pelagic longline fisheries. Space use hotspots of commercially valuable sharks and of internationally protected species had the highest overlap with longlines (up to 76% and 64%, respectively) and were also associated with significant increases in fishing effort. We conclude that pelagic sharks have limited spatial refuge from current levels of high-seas fishing effort. Results demonstrate an urgent need for conservation and management measures at high-seas shark hotspots and highlight the potential of simultaneous satellite surveillance of megafauna and fishers as a tool for near-real time, dynamic management
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