|Date||6 Sep 2017|
Near Vamizi Island, in the far Northern Quirimbas Archipelago of Mozambique there is a large aggregation of female grey reef sharks. Between July and late November, we have discovered that loose aggregations of up to 30 sharks occur on a specific site. All the sharks are mature females, and most, if not all, are pregnant suggesting that these aggregations may have something to do with reproduction.
Studies of similar grouping behaviour in grey reef sharks off Johnston Atoll in the Central Pacific suggest that by aggregating in warm water the rate of embryonic development may increase. Perhaps these female-only aggregations simply occur in a designated place to avoid amorous, nippy males during the reproductive season. Because of this aggregating behaviour the grey reef shark is very susceptible to moderate fishing pressure. Besides the South Sudan aggregation and other similar aggregations in the Seychelles, the Vamizi aggregation is one of very few known in the western Indian Ocean, and the only one along the East African Coast, an area where shark populations are severely threatened and there is concern over regional shark populations.
In previous years, while studying the sharks with discover other spawning aggregations in neptunes that we want to uncover next year like the giant grouper. In also are engaging with communities and government to protect this unique place and we hope that next year we could finally move forward with a MPA in this area.
Read about Isabel's previous project https://www.rufford.org/projects/isabel_marques_da_silva_0 or for more information contact: