HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2021
A submarine dive allowed the observation of a mature male individual of the prickly shark Echinor... more A submarine dive allowed the observation of a mature male individual of the prickly shark Echinorhinus cookei (Pietschmann, 1928) at –500 m depth on the outer slope of the barrier reef off the island of Moorea (Society Islands, French Polynesia). This identification extends the range of this species in the Eastern Tropical Pacific, between Hawaii in the West and the Peruvian coasts in the East.
Understanding why sharks bite humans is essential for developing strategies to prevent these inci... more Understanding 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.
Identifying the species and size of sharks responsible for biting humans is essential for develop... more Identifying the species and size of sharks responsible for biting humans is essential for developing strategies to prevent these incidents. Here, we use bite wound characteristics and genetic analysis of a tooth fragment extracted from the wounds to identify a sicklefin lemon shark Negaprion acutidens as the perpetrator of nonfatal bites on the legs of an adult male surfer at Makemo atoll (French Polynesia) in January 2018. The bite was superficial, and N. acutidens are fish predators not known to feed on large prey; hence, foraging is an unlikely explanation for this incident rather linked to territoriality. Lemon sharks are occasionally aggressive toward humans and are site attached with relatively small home ranges; hence, avoiding surfing in the area of a previous bite incident is recommended to decrease the risk of future injuries.
Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fi... more Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fish and other marine organisms in challenging environments. The development of a long duration (24 h) surface BRUV observation surveys allowed the monitoring of scarce and elusive pelagic sharks and the direct impact on non-targeted species of longline fishing in the Western Mediterranean. Technological limitations, such as the limited storage capacity and a single surface camera, were improved by (i) adding a deep camera equipped with light (below 80 m depth) and (ii) replacing Gopros with a multi-camera video surveillance system (surface and depth) with a storage capacity of several days and access to real-time observation. Based on a deployment effort of 1884 h video data, we identified 11 blue sharks (Prionace glauca) and one bluntnose sixgill shark (Hexanchus griseus), a deep-sea species that scarcely swims at the surface. The real-time observation capability was a powerful tool for ...
Background The tiger shark (Galeocerdo cuvier) is a large iconic marine predator inhabiting world... more Background The tiger shark (Galeocerdo cuvier) is a large iconic marine predator inhabiting worldwide tropical and subtropical waters. So far, only mitochondrial markers and microsatellites studies have investigated its worldwide historical demography with inconclusive outcomes. Here, we assessed for the first time the genomic variability of tiger shark based on RAD-seq data for 50 individuals from five sampling sites in the Indo-Pacific (IP) and one in the Atlantic Ocean (AO) to decipher the extent of the species’ global connectivity and its demographic history. Results Clustering algorithms (PCA and NMF), FST and an approximate Bayesian computation framework revealed the presence of two clusters corresponding to the two oceanic basins. By modelling the two-dimensional site frequency spectrum, we tested alternative isolation/migration scenarios between these two identified populations. We found the highest support for a divergence time between the two ocean basins of ~ 193,000 year...
There is an increasing interest in touristic observations of top predators in the wild. Sharks ar... more There is an increasing interest in touristic observations of top predators in the wild. Sharks are probably the most sought-after animal in marine ecosystems by divers. Regulations have been put in place, and even if they are more or less respected, providing food is still used in some places in order to attract wild animals. Because of the difficulty in sampling shark guts, few studies have analyzed the microbiota of sharks, and none have evaluated the effect of feeding on this microbiota. In this work, we compare microbiota assemblages of black-tip sharks between sites with and without regular feeding. Our results revealed a significant feeding effect on both alpha and beta diversities of microbiota. Notably, the alpha diversity of fed sharks was lower than unfed sharks. We hypothesize that this result is related to a lower diversity of food intake by sharks in places where feeding is regularly provided. More studies need to be conducted in order to estimate the impact of feeding ...
A submarine dive allowed the observation of a mature male individual of the prickly shark Echinor... more A submarine dive allowed the observation of a mature male individual of the prickly shark Echinorhinus cookei (Pietschmann, 1928) at –500 m depth on the outer slope of the barrier reef off the island of Moorea (Society Islands, French Polynesia). This identification extends the range of this species in the Eastern Tropical Pacific, between Hawaii in the West and the Peruvian coasts in the East.
A mission on the Chesterfield reefs (Coral sea, Western Pacific) in November 2011 allowed the unp... more A mission on the Chesterfield reefs (Coral sea, Western Pacific) in November 2011 allowed the unprecedented identification of juvenile lemon sharks Negaprion acutidens.
A mission on the Clipperton atoll (Eastern Tropical Pacific) in February 2016 allowed the unprece... more A mission on the Clipperton atoll (Eastern Tropical Pacific) in February 2016 allowed the unprecedented identification of an adult individual of giant trevally Caranx ignobilis (Forsskål, 1775).
HAL (Le Centre pour la Communication Scientifique Directe), Oct 1, 2021
A submarine dive allowed the observation of a mature male individual of the prickly shark Echinor... more A submarine dive allowed the observation of a mature male individual of the prickly shark Echinorhinus cookei (Pietschmann, 1928) at –500 m depth on the outer slope of the barrier reef off the island of Moorea (Society Islands, French Polynesia). This identification extends the range of this species in the Eastern Tropical Pacific, between Hawaii in the West and the Peruvian coasts in the East.
Understanding why sharks bite humans is essential for developing strategies to prevent these inci... more Understanding 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.
Identifying the species and size of sharks responsible for biting humans is essential for develop... more Identifying the species and size of sharks responsible for biting humans is essential for developing strategies to prevent these incidents. Here, we use bite wound characteristics and genetic analysis of a tooth fragment extracted from the wounds to identify a sicklefin lemon shark Negaprion acutidens as the perpetrator of nonfatal bites on the legs of an adult male surfer at Makemo atoll (French Polynesia) in January 2018. The bite was superficial, and N. acutidens are fish predators not known to feed on large prey; hence, foraging is an unlikely explanation for this incident rather linked to territoriality. Lemon sharks are occasionally aggressive toward humans and are site attached with relatively small home ranges; hence, avoiding surfing in the area of a previous bite incident is recommended to decrease the risk of future injuries.
Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fi... more Bait-based remote underwater video (BRUV) systems are effective devices for remotely observing fish and other marine organisms in challenging environments. The development of a long duration (24 h) surface BRUV observation surveys allowed the monitoring of scarce and elusive pelagic sharks and the direct impact on non-targeted species of longline fishing in the Western Mediterranean. Technological limitations, such as the limited storage capacity and a single surface camera, were improved by (i) adding a deep camera equipped with light (below 80 m depth) and (ii) replacing Gopros with a multi-camera video surveillance system (surface and depth) with a storage capacity of several days and access to real-time observation. Based on a deployment effort of 1884 h video data, we identified 11 blue sharks (Prionace glauca) and one bluntnose sixgill shark (Hexanchus griseus), a deep-sea species that scarcely swims at the surface. The real-time observation capability was a powerful tool for ...
Background The tiger shark (Galeocerdo cuvier) is a large iconic marine predator inhabiting world... more Background The tiger shark (Galeocerdo cuvier) is a large iconic marine predator inhabiting worldwide tropical and subtropical waters. So far, only mitochondrial markers and microsatellites studies have investigated its worldwide historical demography with inconclusive outcomes. Here, we assessed for the first time the genomic variability of tiger shark based on RAD-seq data for 50 individuals from five sampling sites in the Indo-Pacific (IP) and one in the Atlantic Ocean (AO) to decipher the extent of the species’ global connectivity and its demographic history. Results Clustering algorithms (PCA and NMF), FST and an approximate Bayesian computation framework revealed the presence of two clusters corresponding to the two oceanic basins. By modelling the two-dimensional site frequency spectrum, we tested alternative isolation/migration scenarios between these two identified populations. We found the highest support for a divergence time between the two ocean basins of ~ 193,000 year...
There is an increasing interest in touristic observations of top predators in the wild. Sharks ar... more There is an increasing interest in touristic observations of top predators in the wild. Sharks are probably the most sought-after animal in marine ecosystems by divers. Regulations have been put in place, and even if they are more or less respected, providing food is still used in some places in order to attract wild animals. Because of the difficulty in sampling shark guts, few studies have analyzed the microbiota of sharks, and none have evaluated the effect of feeding on this microbiota. In this work, we compare microbiota assemblages of black-tip sharks between sites with and without regular feeding. Our results revealed a significant feeding effect on both alpha and beta diversities of microbiota. Notably, the alpha diversity of fed sharks was lower than unfed sharks. We hypothesize that this result is related to a lower diversity of food intake by sharks in places where feeding is regularly provided. More studies need to be conducted in order to estimate the impact of feeding ...
A submarine dive allowed the observation of a mature male individual of the prickly shark Echinor... more A submarine dive allowed the observation of a mature male individual of the prickly shark Echinorhinus cookei (Pietschmann, 1928) at –500 m depth on the outer slope of the barrier reef off the island of Moorea (Society Islands, French Polynesia). This identification extends the range of this species in the Eastern Tropical Pacific, between Hawaii in the West and the Peruvian coasts in the East.
A mission on the Chesterfield reefs (Coral sea, Western Pacific) in November 2011 allowed the unp... more A mission on the Chesterfield reefs (Coral sea, Western Pacific) in November 2011 allowed the unprecedented identification of juvenile lemon sharks Negaprion acutidens.
A mission on the Clipperton atoll (Eastern Tropical Pacific) in February 2016 allowed the unprece... more A mission on the Clipperton atoll (Eastern Tropical Pacific) in February 2016 allowed the unprecedented identification of an adult individual of giant trevally Caranx ignobilis (Forsskål, 1775).
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