Shark research - Johann MOURIER

Sharks are more social animals than previously believed

johannmourier — Tue, 27 Dec 2011 00:16:28 +0000

Sharks are usually viewed as solitary predators… However, my last study that has just been published in the journal Animal Behaviour shows the contrary: sharks can have preferred companions and a complex social structure, even at a small scale (10km coastline).

Here is the Abstract of the scientific article (you can find it here).

Evidence of social communities in a spatially structured network of a free-ranging shark species

Johann Mourier ^,, Julie Vercelloni, Serge Planes

Laboratoire d’Excellence « CORAIL » and USR 3278 CNRS-EPHE, Centre de Recherche Insulaire et Observatoire de l’Environnement (CRIOBE) and Centre de Biologie et d’Ecologie Tropicale et Méditerranéenne, France

Received 5 April 2011; revised 30 June 2011; Accepted 14 October 2011. MS. number: 11-00283. Available online 19 December 2011.

Large, solitary, marine predators such as sharks have been observed to aggregate at specific areas. Such aggregations are almost certainly driven by foraging and behavioural strategies making space for diverse spatial organizations. Reef-associated shark species often show strong patterns of site fidelity that could be viewed as a prerequisite for sociality. However, there is limited empirical evidence that such aggregations are driven by intrinsic social factors. Association data for blacktip reef sharks, Carcharhinus melanopterus, were obtained from photoidentification surveys conducted in Moorea coral reefs (French Polynesia). We adapted a social network approach to demonstrate evidence of four main communities and two subcommunities within the population. We confronted the resulting structure with candidate explanatory variables. Sharks formed spatial groups characterized by nonrandom and long-term associations, despite opportunities for social relationships to develop between communities. Sex and length of sharks tended to influence assortment at the population and community levels. Individual space use also explained community structure, although spatial assortment was globally weaker than random expectations, suggesting that observed associations were not an artefact of the sampling design or spatial distribution of individuals. We conclude that the observed grouping patterns not only resulted from passive aggregations for specific resources, but rather the communities developed from an active choice of individuals as a sign of sociability. Individual preferences and adaptation to local conditions, as well as demographic, ecological and anthropogenic factors, may explain the social variability between communities. This suggests that a stable grouping strategy may confer substantial benefits in this marine predator.

Adventure Ocean Quest “Shark paradise of Polynesia”

johannmourier — Wed, 28 Sep 2011 14:24:56 +0000

Release of ADVENTURE OCEAN QUEST (PART 4)
About sharks of French Polynesia including sicklefin lemon sharks (juveniles and adults) of Moorea and Great hammerheads of Rangiroa.

Here is the teaser of the documentary:

52 minutes, produced by Christian Pétron and Boris Raim, with Frédéric Buyle (World Champion ship of Free Diving)
Production: Sound & Vision GMBH et Cinemarine pour ZDF Entreprise.

A film with Frédéric BUYLE, William WINRAM, and Dr Johann MOURIER
Film supported by Polynesian Gouvernment (APAC) and the NRW Bank
Directed by Boris RAIM and Christian PETRON
Camera: Sascha Schöberl
Underwater camera: Christian PETRON

Expedition 2011_Spawning Camouflage Groupers (Epinephelus polyphekadion)

johannmourier — Wed, 27 Jul 2011 07:39:40 +0000

After my PhD defence on blacktip reef shark’s behavioural ecology, I was part of an expedition and started a new CRIOBE project in collaboration with Michael Domeier and other scientists in a special place in French Polynesia were Camouflage Groupers (Epinephelus polyphekadion) aggregate a month a year for spawning. The place is also characterized by the presence of undreds of grey reef sharks as well as tenth of blacktip sharks (Carcharhinus limbatus). We started to study this almost pristine ecosystem from sharks to fish.

During the spawning aggregation of groupers, plenty of grey reef sharks enter in feeding frenzy and predate on groupers.

Check out this video I made, begining with the shark wall, then with the begining of grouper aggregation and finishing with spawning and predations (predation at 08:18).

New paper on the economic value of sicklefin lemon sharks in Moorea

johannmourier — Mon, 04 Jul 2011 04:06:04 +0000

Business partner or simple catch? The economic value of the sicklefin lemon shark in French Polynesia

Most arguments invoked so far by the scientific community in favour of shark conservation rely on the ecological importance of sharks, and have little impact on management policies. During a 57-month study, we were able to individually recognise 39 sicklefin lemon sharks that support a shark-feeding ecotourism activity in Moorea Island, French Polynesia. We calculated the direct global revenue generated by the provisioning site, based on the expenses of local and international divers. The total yearly revenue was around USD5.4 million and the 13 sharks most often observed at the site had an average contribution each of around USD316 699. Any one of these sharks represents a potential contribution of USD2.64 million during its life span. We argue that publicising economic values per individual will be more effective than general declarations about their ecological importance for convincing policy makers and fishers that a live shark is more valuable than a dead shark for the local economy. Studies monitoring the potential negative ecological effects of long-term feeding of sharks should, however, be conducted to ensure these are also considered. Besides declarations about the non-consumptive direct-use value of sharks, as promoted by ecotourism, the calculation of their other economic values should also benefit shark conservation.

Clua, E, N. Buray, P. Legendre, J. Mourier & S. Planes (2011) Business partner or simple catch? The economic value of the sicklefin lemon shark in French Polynesia. Marine and Freshwater research 62: 764-770.

you can find the paper in free access: here

PhD defense 3 Mai 2011 _ Social networks and complex behaviours in sharks

johannmourier — Mon, 16 May 2011 00:46:12 +0000

I just defended my PhD on behavioural ecology of sharks in French Polynesia. Here is the abstract:

TITLE:

Social networks and complex behaviours in sharks

ABSTRACT

Social behaviour is widespread in the animal kingdom. Despite evidence of shark aggregations, little is known about their organisation and behaviour. In this thesis, the patterns and mechanisms underlying the social organisation of free-ranging sharks were investigated using the blacktip reef shark (Carcharhinus melanopterus) as a model species. Social organisation is often influenced by the spatial distribution of individuals. Strong site attachment displayed by blacktip reef sharks suggests possible repeated interactions between individuals as a prerequisite for sociality. Spatio-temporal associations between individuals allowed building a social network that describes non-random social preferences between 133 individual sharks. As the social organisation is also characterised by different strategies, molecular analyses revealed that females return to the same nursery to give birth and that many offspring show a high degree of inbreeding. At the end, the influence of genetic similarity on the social behaviour of sharks was investigated, revealing that sharks were more related within than among social groups. This thesis reveals for the first time evidence of a complex social organisation in adult sharks, indicating that group formation is an important behavioural strategy for sharks that likely improves survival and fitness. Often considerate as primitive and solitary animals, sharks appear to be able of complex social behaviour and underlying strategies. These results emphasise the need to include these novel insights into conservation plans.

CRIOBE holding a documentary for shark research in French Polynesia

johannmourier — Thu, 07 Jan 2010 20:50:30 +0000

In December, I was involved in a documentary about sharks and shark research in French Polynesia. A crew including famous Christian PETRON and 2 champion free-divers Fred BUYLE and William WINRAM came in Moorea to film and tag lemon sharks and blacktip reef sharks. For more info, have a look at there link: http://oceanencounters.net/journal/2009/12/blacktip-reef-and-lemon-sharks-galore/

We thus made good images of reef sharks in order to change the usual bad view people have about them and we succeeded in tagging lemon sharks.

After few weeks in Moorea, we left to Rangiroa as part as another projet, to film and tag a Great Hammerhead shark with a satellite tag. Previous acoustic tagging have shown that this sharks stay in Rangiroa from December until February and leave the area afterward. Satellite tag will let us know where they are going after February.

This was a great experience and I hope the documentary will help to better conserve sharks.

For more info about the 2 amazing free-divers that are doing a great work to change people’s mind about sharks, have a look at their web-pages:

http://williamwinram.com/

http://nektos.net/

Back for last field season

johannmourier — Thu, 05 Nov 2009 21:00:29 +0000

Back in Moorea at the parturition season of reef shark, both Negaprion acutidens and Carcharhinus melanopterus, it is time to sample the newborns for future parentage analysis to investigate breeding patterns of sharks of Moorea.

Photo-identification of an homogenous bodied shark: the sicklefin lemon shark

johannmourier — Sun, 05 Jul 2009 17:50:52 +0000

We just published a paper testin successfully the use of photo-identification technique to identfy each individual of a population of sicklefin lemon sharks (Negaprion acutidens). This technique was found to be suitable for future behavioural studies. For a PDF copy, please send me an email at johann.mourier@gmail.com.

Buray, N., J. Mourier, S. Planes, & E. Clua (2009). Underwater photo-identification of sicklefin lemon shark, Negaprion acutidens, at Moorea (French Polynesia). Cybium 33(1): 21-27

“Sur les traces du requin pèlerin” (Basking shark behaviour)

johannmourier — Wed, 24 Jun 2009 14:04:48 +0000

In June 2009, I joined the French research team APECS and Sandra Bessudo (Malpelo Fundation) in a field trip in Britany (France) to tag basking sharks. The recent studies on basking shark’s movements have demonstrated different behavioural patterns of movements from local movements (in Britain waters) to transoceanic migration (Atlantic) and Transequatorial migration (Atlantic). But what are our French basking sharks doing? Is there an exchange between French and English populations? The PAT tag will answer these questions…

Tetiaroa 2009

johannmourier — Fri, 01 May 2009 23:50:16 +0000

A new 2 days field trip to Tetiaroa to catch other juvenile sharks to investigate regional connectivity in shark populations.