New grey reef shark (Carcharhinus amblyrhynchos) nursery in the Mozambico channel close to Nosy be Island – Madagascar

Grey reef sharks (Carcharhinus amblyrhynchos), are included in the IUCN red list as near threatened, however, their biology is still relatively little known. Discordant data are available on their tendency to be site fidelity, studies carried out in Australia indicate limited reef fidelity and evidence of largescale movements within northern Australian waters, while site fidelity and residency of grey reef sharks on the outer slope of coral reefs in Palau, Micronesia, over a period of two years and nine months were detected regularly throughout another study and sharks displayed strong inter-annual residency with greater attendance at monitored sites during summer than winter months. However, it is commonly believed that Grey reef sharks display strong levels of site fidelity that persist across years, at least for some components of the population. Site fidelity is a common phenomenon in many species, including whitetip (Triaenodon obesus), tawny nurse (Ginglymostoma cirratum), blacktip (Carcharhinus melanopterus), Caribbean (C. perezi) and grey reef (C. amblyrhynchos) sharks. The degree of fidelity appears to vary according to life history stage, availability of resources and area of suitable habitat. Site fidelity is also common in adult reef sharks, although typically more sporadic when compared to juveniles, which might be partially explained by ontogenetic increases in the size of home ranges. Off Nosy be in Madagascar in the Mozambique channel, we have identified a new probable nursery that is being monitored by CSS (Centro Studi Squali) since 2017, thanks to the logistical and underwater support of the Manta Diving. Around the pinnacle of a coral reef at about 15-30 meters depth, grey reef sharks patrol daily, specimen sizes between 50cm and 200cm. The importance of identifying and reporting nursery areas for this species, is a priority to promote its proper conservation.