50 research outputs found
The Accidental Capture of a Newborn Shortfin Mako Shark Isurus oxyrinchus (Rafinesque, 1810) in the Northwestern Mediterranean Sea off the Coast of Marseille, France
No full textA small-sized shark was accidentally caught in the coastal waters of southeastern France and abandoned in the port of L’Estaque (Marseille) in May 2024. An autopsy revealed that it was a young female shortfin mako, Isurus oxyrinchus (Rafinesque, 1810). Numerous superficial wounds on the head, back, and flanks, in the form of parallel striations resulting from heavy friction, indicate meshing in a gillnet that provoked the animal’s death by asphyxiation. Its very small size (64.77 cm TL) suggests that this is a newborn individual, leading to the hypothesis that the waters off Marseille could be a nursery area for this species. This observation alone is not enough to prove this point, but it does suggest the need for closer monitoring to validate it. Should the area be proven to play this key role for this critically endangered species, measures to limit fishing pressure would be essential, particularly during the parturition period between February and May
Marine Science and Engineering A Time-Extended (24 h) Baited Remote Underwater Video (BRUV) for Monitoring Pelagic and Nocturnal Marine Species
No full textInternational audienceBaited remote underwater video systems (BRUVs) are efficient devices for remotely characterising the assemblage and relative density of fishes and other marine organisms. However, technological constraints (e.g., battery life and limited storage memory) typically limit deployment times to <2 h making it very difficult to capture the presence of marine species, including rare and elusive ones. We developed an extended duration (24 h) BRUV to enable fisheries-independent surveying of a pelagic shark population in the western Mediterranean. Video data revealed seven visits (three nocturnal, four diurnal) by blue sharks (Prionace glauca) over a period of 1355 h. In the future, this cost-effective device could be fitted with a wireless video transmitter to provide real-time observations of marine animals for scientific or ecotourism purposes
The ‘Mistaken Identity Hypothesis’ for shark bites on humans is an anthropomorphic fallacy
No full textInternational audienceThe Mistaken Identity Hypothesis (MIH) interprets shark bites on surfers, swimmers and snorkelers as 'mistakes' stemming primarily from similarities in the visual appearance of ocean users and the sharks typical prey. MIH is now widely accepted as fact by the general public and some sections of the scientific community despite remaining unproven. This hypothesis assumes that 'mistaken' shark bites on humans result primarily from confusing visual cues and ignores the important role of other senses (e.g. hearing) in discriminating potential prey. A far simpler 'natural exploration' hypothesis can reasonably explain not only shark bites that have been characterized as 'mistaken identity' events but also those that cannot be reasonably explained by MIH (e.g. shark bites that occur in very clear water). Simply stated, sharks don't make 'mistakes' but instead continually explore their environments and routinely investigate novel objects as potential prey by biting them
off Moorea island (French Polynesia)
No full textInternational audienceUnderstanding why sharks bite humans is essential for developing strategies to prevent these incidents. Here, we use bite wound characteristics and eye witness descriptions of shark behavior to determine the likely motivation for several bites perpetrated by an oceanic whitetip (OWT) shark Carcharhinus longimanus on an adult female snorkeler off Moorea island (French Polynesia) in October 2019. The victim was snorkeling with others in pelagic waters as part of an organized whale-watching tour when the shark—without any warning behavior—bit her at least three times resulting in severe injuries with substantial loss of soft tissue from the chest and both forearms. The victim survived these injuries thanks to rapid and effective first aid provided by her companions. The sudden, unprovoked and repeated bites with substantial tissue removal are consistent with predatory behavior although the dominance hypothesis cannot be fully ruled out. This would be the first case of a predatory shark bite ever documented in French Polynesia in over 70 years of data collection. Given the routine association of OWT sharks with cetaceans, in-water whale watching activities should adopt appropriate risk management strategies in regions hosting this species of shark
Individual shark profiling: An innovative and environmentally
Get PDFMost shark-induced human fatalities are followed by widespread and unselective
culling campaigns that have limited effectiveness and may have high ecological costs
for threatened species. The blanket culling strategy implicitly assumes that incident
risk is directly correlated with shark density, an assumption that has yet to be demonstrated.
We present the alternative hypothesis that incidents are more likely to be
caused by behavioral variability among individual sharks than due to shark density.
Throughout their ontogenetic development, large species of sharks opportunistically
establish a diet that is rarely, if ever, inclusive of humans as a food source. We propose
that, some animals with specific behaviors (including boldness) may potentially
pose a higher risk than conspecifics. Under this scenario, the risk of a shark attack in
a given area would relate to the presence of a limited number of high-risk individuals
rather than shark density.
In terms of management of human fatalities, such a hypothesis would favor abandoning
general culling campaigns and replacing them with approaches that profile
and selectively remove the potential problem individuals, as is done in the terrestrial
realm when managing predators that attack humans or livestock.publishedVersio
First tiger shark Galeocerdo cuvier bite in 75 years in French Polynesia (Eastern Central Pacific)
No full textWe analyzed a tiger shark (estimated 2.8 m total length) bite on a snorkeler. The removal of the terminal part of the leg suggests a predatory motivation for the bite. This is the first documented bite by a tiger shark in French Polynesia waters for the past 75 years
Forensic‐Based and Environmentally Responsible Protocol to Manage Shark Fatal Bites on Humans Can Better Contribute to Conservation Needs
No full textInternational audienceAlthough sharks are important for marine ecosystems, they still suffer culling campaigns after human fatalities. A case study from the Caribbean shows how the rapid use of several complementary and reproducible forensic techniques not only allowed the confirmation of the species implicated in the bite but also the accurate assessment of the size of the animal. Six non‐lethal fishing sessions led to the capture of several shark individuals that were released after either being eliminated due to their unsuitable size or the absence of human remains in their stomach. Such an ecologically responsible risk management can contribute to shark conservation
