J Appl Ecol 42:999–1011Īuger-Methe M, Whitehead H (2007) The use of natural markings in studies of long-finned pilot whales ( Globicephala melas). Calif Fish Game 89:96–101Īrzoumanian Z, Holmberg J, Norman B (2005) An astronomical pattern-matching algorithm for computer-aided identification of whale sharks Rhincodon typus. Environ Biol Fish 59:117–123Īnderson SD, Pyle P (2003) A temporal, sex-specific occurrence pattern among white sharks at the south Farallon Islands, California. alfredi exists along the Mozambican coastline, management efforts to monitor and prevent overexploitation at these critical habitats should be a priority.Īmorim AF, Arfelli CA, Castro JI (2000) Description of a juvenile megamouth shark, Megachasma pelagios, caught off Brazil. alfredi suggest that many individuals in this population exhibit site fidelity to the examined aggregation sites. Natural markings were unique to individuals and did not change substantially with time, which provided further support for their use in the identification of individual M. Large numbers of rays (20 + per dive) were seen in the months of November, December and January, which coincide with the breeding season. The maximum number of individual rays seen per dive was 30. Manta alfredi were observed at the study sites in each month of the calendar year. The majority of rays (89.9% males 49.7% females) were considered mature, with most individuals between 3.0 and 4.9 m in disc width. A highly significant sex bias was evident with a female:male ratio of 3.55:1. The superpopulation size estimate for the entire study period was 802 individuals, the first reported for M. alfredi ranged from 149 to 454 individuals. During the study period, annual population size estimates for M. The longest period between re-sighting events was 1,252 days. In total, 449 individuals were identified during this time period, 40.5% of which were re-sighted on at least one occasion.

Using these techniques, we report on the size, structure and seasonality of this population of M. The use and standardisation of photo-ID techniques was examined as a minimally-intrusive means to study this species. The size and structure of a photographically identified population of reef manta ray, Manta alfredi, were examined at aggregation sites over a four-year period in southern Mozambique.

Manta ray size