Sharks have increadible healing abilities

Following a nice collaboration with Andrew Chin and Jodie Rummer from James Cook University (Australia), we recently published an article documenting a range of diverse wounds and injuries on the blacktip reef shark (Carcharhinus melanopterus) and demonstrating how quickly sharks were able to heal and recover from these injuries. This healing ability has different implications and application to understanding of shark’s ecology.

We first documented the rapid healing of this species following an internal tagging procedure involving a small incision in the belly of the shark to implant the transmitter. This not only shows that sharks are healing quickly but also that they are robust to this tagging procedure which is important to know as a scientist when you work with free-living animal.

 

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The same kinds of incisions/open-wounds are present in neonate sharks from viviparous species such as the blacktip reef shark. Just after birth, an open umbilical scar is visible but it quickly close and heals. It is then important to assess the speed of healing in ecology as it can inform the approximate date of birth when the juvenile is caught in its nursery. Small umbilical wounds in neonates decreased in surface area by 71% in less than a week and were barely detectable after 24 days.

 

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The same rate of healing is helpful when females are bitten by males during mating. Indeed, as it is really rare to observe shark copulation, we can indirectly infer when mating occurred using the fresh bite wounds on female’s body. Inferring the speed of healing of these wounds can therefore tell us exactly when mating occurred.

 

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Blacktip reef sharks can also have other sources of injuries. For example, larger sharks or other conspecifics can bite them during agonistic/dominance behaviour or predation attempt by larger predators, and healing quickly is therefore important.

 

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Anthropogenic activities can injure sharks (e.g. boat propellers). We report here an unbelievable healing case of a shark surviving a serious deep wound that might have been inflicted by a boat propeller in Moorea lagoon. I less than a month the wound closed completely.

 

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Finally, we reported two cases of survival after fin removal due to targeted shark-finning in which the basal wound of fin removal healed well and the sharks were observed alive a while after injury, swimming without their dorsal fin. However, even if they survive for un unknown time, the removal of the dorsal fin may greatly affect their daily life and in turn their fitness (and most of finned sharks may not survive).

 

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In summary, this study suggests that elasmobranchs may be resilient to injuries, showing rapid healing from minor wounds and long-term survival from even major mechanical injuries. These are positive findings for elasmobranch conservation, especially considering that up to a quarter of all shark and ray species worldwide are threatened with extinction. Despite this incredible ability, we encourage minimal handling time and stress when releasing sharks after fishing or by-catch, which could include cutting a line near the hook instead of repeatedly attempting to remove the hook. Anglers should also be made aware that sharks can recover from mechanical injury; therefore, sharks should be released even if the animal sustains injuries during the capture process.

 

The paper is Open Access and available at:

Chin A, Mourier J, Rummer J (2015) Blacktip reef sharks (Carcharhinus melanopterus) show high capacity for wound healing and recovery following injury. Conservation Physiology 3(1): cov062

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What is known about effects of provisoning on sharks and ray and how future research should investigate different scales?

We recently published a paper that review the research that has been conducted so far on the effect of shark and ray provisioning on the animal’s ecology, behaviour and health.

Shark and ray provisioning is a rapidely growing indstry that offers tourist with an increased probability of interaction with elusive animals buy attracting them with food or even feeding them to habituate them to visit the diving site. This activity is widespread around the world and involve different species.

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We reviewed the 22 available studies on this topic involving 14 shark and 3 ray species targeted by artificial provisioning to investigate their behavioral, physiological, and ecological response.

We first report similar individual response by sharks and rays, including change in horizontal movements or emergence of an anticipatory response. However, all studies demonstrate that the propensity to respond to provisioning operations varies both among elasmobranch species and among individuals within each species. The effect on diet and foraging behaviour is yet to be better investigated as this topic has been understudied so far; the 2 availaible studies showing contrasting patterns that might be due by different provisioning practices.

We also investigated the potential effects at the group scale. We report a number of studies showing an aggregation effect with an increased abundance of the targeted species at the feeding site. Provisioning operations can influence group composition in terms of species and genders that are aggregated. It can aggregate naturally gregarious species but also solitary species creating an artificial interacting zone. However, most studies indicate that there is unlikely an effect on the natural cycle of the species involved, as for example, most species appear to keep conducting their breeding migrations despite the possibility to stay at the provisioning site. On the other hand, aggregation at a specific site can promote intra-specific aggression or competition.

We also reported the community-scale effects, including the effects of distribution of predators and prey or chnaging elasmobranch communities at the feeding site.

Although the effect on elasmobranch health has been yet underinvestigated, we discuss the potential effects that may impact animal’s health and body condition.

While a growing number of ecologists is investigating the potential effects of provisioning on sharks and rays, we took the opportunity to suggest a framework that take into account multi-scales when studying this topic. Until now, most of the studies have only been context dependent and focused on only one or two effects (e.g., effects on abundance or on movement patterns), but we highlight teh fact that scientists should now intergrate multiple effects and their interactions within their study. Indeed, most individual, group and community effects are not isolated and actively interact. A broader framework could therefore study the cascading affects accross the scales.

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Such a framework could benefit our understanding of the real effects and their strenght and importance on shark and rays health and behaviour.

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While the review was based on the potential effects of provisioning on sharks and rays, we also show that it is context dependent and not necessarily negative. This activity can have positive effect for conservation and awareness, or even null effects on some aspects. The strenght of negative effects is often related to the practices of the industry. If some operations are already conscious on the benefit of good practices to secure the durability of their activity and the health of populations of the species they target (http://globalsharkdiving.org/ , http://sustainablesharkdiving.com/), others only think about short-term financial benefit of the practice and do not adapt their practices to good code of conduct which is likely to negatively impact the industry.

Note also that the reported negative effects are nothing compared to other threats that sharks are facing every day (e.g. overfishing, habitat degradation, climate change…).

We hope our review will provide a good summary of the different effects that have already been studied in sharks and rays but also that it will encourage future researcher to use a broader framework to investigate the response of these marine animals to provisioning.

Our study is available here:

Brena PF, Mourier J, Planes S, Clua E (2015) Shark and ray provisioning : functional insights into behavioral, ecological and physiological responses across multiple scales. Marine Ecology Progress Series 538: 273-283.PDF icon

Which fish can you find in Marquesas Islands? Here is an updated checklist showing 13.7% of endemism!

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Expedition Pakaihi I Te Moana was conducted in 2011 to the Marquesas Islands, lying between 07°50ʹ S and 10°35ʹ S latitude and 138°25ʹ W and 140°50ʹ W longitude. The team made a long trip at sea on ship Braveheart and visited almost all islands of the Marquesas, including a sandbank and some seamonts.

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The expedition combined extensive collections and visual censuses of the shore fish fauna.

A total of 74 species are added as new records for the Marquesas Islands; the coastal fish fauna of the Marquesas Islands is increased from 415 to 495 species and the number of endemic species is increased from 48 to 68 species.

This increases the percentage of species-level endemism for the Marquesas Islands to 13.7%, ranking as the third highest region of endemism for coral reef fishes in the Indo-Pacific. Only two other peripheral regions, the Hawai’ian Islands and Easter Island, have higher values.

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The list also includes elasmobranchs (sharks and rays) including teh 2 species of Manta rays previously described in this paper Mourier 2012.

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The paper is open access:

Delrieu-Trottin E, Williams JT, Bacchet P, Kulbicki M, Mourier J, Galzin R, Lison de Loma T, Mou-Tham G, Siu G, Planes S (2015) Shore fishes of the Marquesas Islands, an updated checklist with new records and new percentage of endemic species. CheckList 11(5): 1758 PDF icon

First Giant grouper (Epinephelus lanceolatus) ever tracked! A 2m beast!

We recently published a scientific paper reporting the first monitoring of movements and residency of a 1.95 m giant grouper in the Chesterfield Islands over almost 3 years.

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Using a nework of 3 six acoustic receivers deployed along the reef we were able to monitor the residency and site use of this large fish. The fish was only recorded by 3 of the 6 receivers with one of it located inside the lagoon being its home reef where it was caught. However, the fish regularly moved to the nearby passes.

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The fish showed higher presence between May and July and interestingly was absent between October and December on 2 years (2010 and 2012), likely to move to an unknown spawning site. However, it didn’t move in 2011.

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Despite being an emblematic fish, this is the first time this species has been tagged and its movement followed. This study provides the first baseline data on the movement and residency patterns of this species which is important for conservation programs and we suggest that other studies should be conducted in other reef of teh world to better understand the spatial behaviour of such rare and large coral reef predators.

Related published paper can be found at:

Clua E, Chauvet C, Mourier J, Werry JM, Randall JE (2015) Pattern of movements from a home reef in the Chesterfield Islands (Coral sea) by the endangered Giant Grouper, Epinephelus lanceolatus. Aquatic Living Ressources 28: 53-58. PDF icon

Movement of Caribbean reef fish

Garcia J, Mourier J, Lenfant, P (2015) Spatial behavior of two coral reef fishes within a Caribbean Marine Protected Area. Marine Environmental Research. Link to paper.

New paper on a collaboration with Jessica Garcia on movement patterns of two species of Caribbean reef fish within a Marine Protected Area in Martinique. In this region, only few data on movements are available on these species. Following Jessica’s first paper (Garcia et al. 2014) on the movement of fish in and out of the MPA, this new paper profides finer-scale movement data to better understand habitat use and spatial dynamic of these species with different trophic positions inside the MPA.

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Figure 1: Description of the study location and receiver array.

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Figure 2: Daily detections of Lutjanus apodus

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Figure 3: Daily detections of Sparisoma viride

Both species differ in their activity within the area with L. apodus being more present along the reef at night while S. viride shows a peak of presence at sunrise and sunset. Habitat use of L. apodus is mostly restricted to reefs while S. viride occasionally use silt habitats (Figure4).

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Figure 4: Probabilities of presence of both species in the study area. Left: Lutjanus apodus. Right: Sparisoma viride. Top panel: time of day. Bottom panel: habitats.

They also show different spatial dynamics (Figure 5).

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Figure 5:Spatial network of movements including transition probabilities between receivers.

These results demonstrate the importance of including multiple species when considering movement patterns and habitat use of fish in MPA design.

GOMBESSA 2 “Le mystère Mérou”: a ARTE documentary of our scientific expedition

Check this official treaser from ARTE documentary (90 min) to be screened in July 11th.

This documentary (Produced by Gil Kébaili) was made last year in a channel of an Atoll of French Polynesia during a scientific expedition to study the spawning aggregation of camouflage groupers and its interaction with a huge (>700) aggregation of grey reef sharks.

During the film, Laurent Ballesta did a 24h dive at 20m depth possible with a new and original gaz mix, spending a complete day underwater with sharks and groupers.

This expedition (collaboration between Andromède Oceanologie and CRIOBE and sponsored by BLANPAIN and ARTE) not only resulted in an incredible documentary but also in real important scientific data about the mechanisms governing spawning aggregations of fish as well as long-term aggregation of sharks. I am currently analysing the data and hopefull the results will come soon…

You can also watch it in Full HD on the sponsor BlancPain website: HERE

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New (French) Book on the use of networks in ethology and ecology

Directed by Cédric Sueur, this book in French has just been published and is a reference for the use of network analysis for ethological and ecological studies!

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More information can be found here: http://www.materiologiques.com/Analyse-des-reseaux-sociaux

In this book I have written 2 chapters including one on social networks in fish and the other on social network and genetic diversity:

Mourier, J. & S. Planes (2015). Réseaux sociaux chez les poissons. Dans « Analyse des réseaux sociaux appliquée à l’éthologie et l’écologie». (Ed: Cédric Sueur) Editions Matériologiques. Paris, France. pp. 137-161.
Mourier, J. & S. Planes (2015). Structure des réseaux et diversité génétique. Dans « Analyse des réseaux sociaux appliquée à l’éthologie et l’écologie». (Ed: Cédric Sueur) Editions Matériologiques. Paris, France. pp. 359-406.