Males blacktip reef sharks prefers the fore reef while females choose the lagoon at a tropical island.

My new paper recently published in Journal of Fish Biology described population characteristics of blacktip reef sharks at Moorea (French Polynesia).

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This paper gathered capture data of this reef species during my PhD thesis to determinate some biological parameters such as mean size, growth and male size at maturity. It includes a review of the same existing parameters in previous studies at other locations and showed that Moorea’s sharks are bigger (on average) than those of other locations such as Australia, Aldabra (Indian Ocean) or Palmyra (Pacific Ocean). Indeed, maximum size of both males (139 cm) and females (157 cm) are higher, as well as size at maturity for males (111 cm) and size at birth (48 cm). Adult sharks grow an average 6 cm/year.

While this species have recently demonstrated that it was able to be social (see paper in Animal Behaviour), this paper show that at the island scale males and females have different habitat differences with males caught mainly on the fore reef while females caught in the lagoon. These informations have important implication for the evolutionary strategy of this species as well as for conservation.

Here is the abstract:

Mourier, J., Mills, S.C. & Planes, S. (in press). Population structure, spatial distribution and life history traits of blacktip reef sharks Carcharhinus melanopterus at Moorea, French Polynesia. Journal of Fish Biology.

During a survey of the population of blacktip reef shark Carcharhinus melanopterus in Moorea (French Polynesia) between 2007 and 2011, population structural characteristics were estimated from 268 individuals. Total length (LT) ranged from 48 to 139 cm and 48 to 157 cm for males and females, respectively, demonstrating that the average LT of females was larger than that of males. The C. melanopterus population at Moorea showed an apparent spatial sexual segregation with females preferentially frequenting lagoons and males the fore-reefs. Mean growth rate was c. 6 cm year−1. Males reached sexual maturity at 111 cm LT. This study reports on the population characteristics of this widespread carcharhinid shark species and makes comparisons with other locations, confirming high geographic variability in the population structure of the species.

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