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.

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

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…

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

In a week 2 scalloped hammerhead shark pups (S. lewini) were observed inside Opunohu bay. We thus took the opportunity to get genetic samples. This confirms also that Opunohu bay is a nursery area for this species.

Movement and group structure in wild blackfin reef sharks, Carcharhinus melanopterus, at Moorea,
French Polynesia
Johann Mourier and Serge Planes
Centre de Recherche Insulaire et Observatoire de l’Environnement (CRIOBE), BP 1013, 98729 Papetoai, Moorea,
French Polynesia
johann.mourier@univ-perp.fr

Abstract:
The blackfin reef shark (Carcharhinus melanopterus) is the most abundant shark species of Polynesian reef communities. Despite its abundance, many aspects of its basic natural history remain poorly or incompletely documented. The blackfin reef shark, neither a solitary nor a schooling fish, is often seen in small aggregations, especially when feeding. Such group living is commonly observed in shark populations, but relatively little is known about the overall organisation, structure, and complexity of these groups. Using a combination of approaches including tagging, photo-identification and genetics, this study aimed to document whether reef shark population organisation is structured or random. Twenty blackfin reef sharks were tagged with Vemco Rcode acoustic transmitters (model V16) and six Vemco VR2 acoustic receivers were deployed. Preliminary results show that sharks demonstrate a high degree of site fidelity with small home ranges. These results suggest that stable group living may be present in this species in the wild. On different sites around the island of Moorea, sharks were caught, photo-identified and DNA sampled for microsatellite analysis. Subsequent underwater surveys using distinctive markings to identify individuals, combined with our genetic results enabled group composition and relatedness to be analysed. Our research will determine whether shark groups are composed of close relatives or are randomly structured.

As a PhD student at CRIOBE studying sharks in French Polynesia, the Fisheries Authorities contacted me to informe us that the tiger shark was caugth . At first they said that it was a pregnant female with pups that started to go out of the body. When we arrived we saw that it was a male. The babies that saw was the 2 claspers. This male was exactly 3.6 m long but we didn’t have the material to weigth the shark. But I think it could weigth about 500kg. We took DNA samples and we opened the body to have a look at the stomack both for stomack contents and parasite analysis. The stomack was almost empty. It only contained some vertabrae that should belong to small shark or fish, and some fibres that we think could be whalebone plates of small cetacean.

In the begining of 2009, I had the chance to go to a remote atoll of the Tuamotus archipelo in French Polynesia to study its shark population. This atoll has the particularity to be almost closed with only a little and really swallow pass that almost cut the lagoon from the ocean. The Polynesian Service of Fisheries asked us to estimate the population size of C. melanopterus that is believe to be really high inside this lagoon. This was also the opportunity to take genetic samples of remote shark populations.

Help support to get the year 2009 or 2010 officially designed as Shark Year.

Elucidating shark movements and therefore habitat use is important for management and conservation of commercially fished and endangered species, as it enables the characterization of species’ critical habitats.

Six passive acoustic monitors (listening stations VR2), capable of recording the presence of multiple acoustic transmitters, will be deployed in Moorea Island (2 inside the lagoon and 4 on the outer slope) to collect and store information from acoustic tags. These individual, fixed-position listening stations can provide information about the presence/absence of tagged individuals at a specific site.

We plan to tag 20 sharks with acoustic transmitters (10 males and 10 females).