Ile Alcatraz et Ile du Naufrage (6364)
Guinea, Africa

Site overview

KBA status: confirmed

Global KBA criteria: D1a

Year of last assessment: 2001

National site name: Ile Alcatraz et Ile du Naufrage

Central coordinates: Latitude: 10.6333, Longitude: -15.3833

System: marine, terrestrial

Elevation (m): 0 to 12

Area of KBA (km²): 0.46773

KBA classification: Global

Legacy site: Yes

Site details

Site description: Ile Alcatraz (0.75 ha) is a lateritic rock islet on the continental shelf of the Atlantic Ocean, 40 km south-west of Iles Tristao (IBA GN004). The Ile de Naufrage (0.25 ha) is a sandbank 2 km south-west of Ile Alcatraz which is exposed even at high tide. Ile Alcatraz is unvegetated and covered with guano to a depth of about 3 m, which is the cause of its white appearance. The Ile de Naufrage is also unvegetated and reaches a maximum height of c.3 m above high water. The intertidal area is mainly sandy.

Rationale for qualifying as KBA: This site qualifies as a Key Biodiversity Area of international significance that meets the thresholds for at least one criterion described in the Global Standard for the Identification of KBAs.

Additional biodiversity: See Box for key species. Ile Alcatraz holds the only known breeding colony of Sula leucogaster between Cape Verde and São Tomé and Príncipe. There is breeding activity throughout the year. The Ile de Naufrage provides a roost for thousands of terns including Sterna maxima, S. hirundo, S. sandvicensis, S. albifrons and Chlidonias niger. Non-bird biodiversity: Among mammals, the dolphin Sousa teuszi (DD) and the sirenian Trichechus senegalensis (VU) are reported from the area; sea-turtles also occur.

Delineation rationale: Type 1 marine IBA: suitable for the seaward extension approach. Type 2 marine IBA: non-breeding (coastal) congregations.

Habitats

Land use: nature conservation and research

Threats

Summary of threats to biodiversity at KBA: The area was designated a Ramsar Site in 1992. Guinean industrial and artisanal fishermen avoid this area of shallow waters because of the dangers of navigation. It is necessary to ensure that foreign fishermen do the same. In the past (40–60 years ago) guano on the island was extracted for phosphate, a practice which had a serious negative impact on the population of Sula leucogaster. The designated shipping lane to the port of Kamsar passes a few dozen kilometres south of the site and there is, therefore, some risk of oil pollution. The islands are state owned.

Threat level 1	Threat level 2	Threat level 3	Timing
Pollution	Industrial & military effluents	Oil spills	Only in the future

Additional information