Isabel Marques da Silva
Other projects
18 Jun 2014
Conservation and Management of Reef Sharks in the Western Indian Ocean through Scientific and Local Community Collaborative Actions
14 Oct 2015
Conservation and Management of Reef Sharks in the Western Indian Ocean: A Conservation Area to Protect Biodiversity and Serve Community and Tourism
Fish spawning aggregations are site attached on a seasonal basis rendering them highly susceptible to localized extirpation, moreover, when these fishes are in the IUCN-Red list like the Grey reef shark, the Giant grouper or the Bumphead parrotfish. These species are already threatened by direct exploitation for fins and meat, increasing migrant artisanal fisheries, and through gas exploration developments. From regional survey data, this area represents one of few sites where large numbers of these threatened fish occur and spawn This project aims to combine acoustic telemetry technology, BRUV’s and community awareness to push for a marine protected community area.
Hammerhead being tagged.
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.
Master students tagging sharks.
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.