Ecologically or Biologically Significant Areas (EBSAs)

  published: 12 Jun 2015

Central Indian Ocean Basin

General Information
This area is known to be a key feeding site for at least four species of seabird that nest on islands in the Western Indian Ocean, with birds migrating over 3000km to feed here during a pronounced seasonal phytoplankton bloom during the austral winter.
This wide region of the central Indian Ocean is the major foraging area for at least four migratory seabirds during their non-breeding season. The site is used by the endangered Barau’s petrel from Reunion Island, two populations of red-tailed tropicbird (from Nosy Ve in Madagascar and from Europa Island), four populations of wedge-tailed shearwater (from D’Arros, Cousin and Aride in Seychelles and from Reunion Island, and white-tailed tropicbird from Cousin Island in Seychelles. It is also used to a lesser degree as a migration stop off point for lesser frigatebird travelling between breeding sites in the Western Indian Ocean and non-breeding areas in South-East Asia.
Description of the location
Southern Indian Ocean
The area lies to the south and east of Sri Lanka and the Maldives, over the mid-Indian Ocean basin and parts of the Ninety East Ridge.
DISCLAIMER: The designations employed and the presentation of material in this map do not imply the expression of any opinion whatsoever on the part of the Secretariat concerning the legal status of any country, territory, city or area or of its authorities, or concerning the delimitation of its frontiers or boundaries.
Area Details
This is the major foraging area for at least four migratory seabirds: the endangered Barau’s Petrel (Pterodroma baraui ), the red-tailed tropicbird (Phaethon rubricauda), the wedge-tailed shearwater (Puffinus pacificus) and the white-tailed tropicbird (Phaethon lepturus). This area can be further sub-divided into two different areas. The first one is a relatively restricted zone located 1200 km to the south of Sri Lanka. This place is important for wedge-tailed shearwaters (from the four studied populations) and for the white-tailed tropicbirds of the Seychelles. The second one is a much larger area lying from 12°S to 18°S and from 78°E to 95°E. This area is used by Barau’s petrel (Pinet et al. 2011) and eed-tailed tropicbird and to a lesser extent by wedge-tailed shearwater and white-tailed tropicbird. These four species use these areas during their non-breeding season only. Presently, we lack additional tracking data and at-sea survey data to evaluate the importance of this region for other seabirds or other top-predators, but the fact that different species from various colonies use these areas clearly shows that there are some oceanic processes there that enhance the foraging success of seabirds during their non-breeding season (Le Corre et al. 2012). These areas are both located at or near bathymetric anomalies. The northern area is just at the surface of a seamount located in the Ceylon abyssal plain (the Afanasy Nikitin seamount) whereas the southern area is on both side of the Ninety East Ridge (Le Corre et al. 2012). Local enrichments due to upwellings induced by these seamounts may explain the high densities of seabirds there. Lévy et al. (2007) showed that a pronounced seasonal phytoplankton bloom appears in the central Indian Ocean during austral winter. Interestingly, the wintering areas of red-tailed tropicbirds and Barau’s petrels co-occur with these winter blooms (Fig. 3e in Lévy et al., 2007), indicating that during winter migratory seabirds likely target prey that are more abundant as a result of local enrichments and associated food webs.
Not known.
Anderson O., Wanless R., Small C. (2009). Seabird By-catch in IOTC Longline Fisheries. BirdLife International. IOTC-2009-SC-INF14. Au D.W.K., Pitman R.L.(1986). Seabird interactions with dolphins and tuna in the eastern tropical Pacific. Condor, 88: 304–317 BirdLife International (2009) Designing networks of marine protected areas: exploring the linkages between Important Bird Areas and ecologically or biologically significant marine areas. Cambridge, UK: BirdLife International. www.cbd.int/doc/meetings/mar/ewbcsima-01/other/ewbcsima-01-birdlife-02-en.pdf BirdLife International (2010) Marine Important Bird Areas toolkit: standardised techniques for identifying priority sites for the conservation of seabirds at-sea. BirdLife International, Cambridge UK. Version 1.1: May 2010. www.birdlife.org/eu/pdfs/Marine_IBA_Toolkit_2010.pdf BirdLife International (2012) Species factsheet: Pterodroma baraui. Downloaded from www.birdlife.org Jaquemet S., Le Corre M., Weimerskirch H. (2004). Seabird community structure in a coastal tropical environment: importance of natural factors and fish aggregating devices (FADs). Marine Ecology Progress Series. Vol. 268: 281–292 Jaquemet S., Le Corre M., Marsac F., Potier M., Weimerskirch H. (2005). Foraging habitats of the seabird community of Europa Island (Mozambique Channel). Marine Biology 147: 573–582 LeCorre M., Jaeger A., Pinet P., Kappes M.A., Weimerskirch H., Catry T., Ramos J.A., Russell J.C., Shah N., Jaquemet S. (2012). Tracking seabirds to identify potential Marine Protected Areas in the tropical western Indian Ocean. Biological Conservation special issue, in press Corrected Proof. Lévy M., Shankar D., André J.M., Shenoi S.S.C., Durand F., de Boyer Montégut C. (2007). Basin-wide seasonal evolution of the Indian Ocean’s phytoplankton blooms. Journal of Geophysical Research, 112 Pinet P., Jaquemet S., Pinaud D., Weimerskirch H., Phillips R.A., Le Corre M. (2011). Migration, wintering distribution and habitat use of an endangered tropical seabird, Barau’s petrel Pterodroma baraui. Marine Ecology Progress Series. Vol. 423: 291–302 Probst J-M., Le Corre M., Thébaud C. (2000). Breeding habitat and conservation priorities in Pterodroma baraui, an endangered gadfly petrel of the Mascarene archipelago. Biological Conservation Volume 93, Issue 1: 135–138 www.seabirdtracking.org – tracking contributors who provided data presented at this workshop are: Maria Ana Dias, Paulo Catry, Teresa Catry, Robert Crawford, Richard Cuthbert, Karine Delord, Jacob Gonzalez-Solis, Jano Hennicke, Matthieu Le Corre, Deon Nel, Malcolm Nicoll, Jose Pedro Granadeiro, Samantha Petersen, Richard Phillips, Patrick Pinet, Jaime Ramos, Jean-Baptiste Thiebot, Ross Wanless, Henri Weimerskirch, Vikash Tatayah.
Status of submission
Areas described as meeting EBSA criteria that were considered by the Conference of the Parties
  • dec-COP-12-DEC-22
Assessment of the area against CBD EBSA criteria
C1: Uniqueness or rarity Low
One of the few known feeding areas for the endangered Barau’s Petrel, which is an endemic breeder to Reunion Island.
C2: Special importance for life-history stages of species High
This area is the key non-breeding site for at least two populations of red-tailed tropicbird (from Nosy Ve in Madagascar and from Europa Island), four populations of wedge-tailed shearwater (from D’Arros, Cousin and Aride islands in Seychelles and from Reunion Island, France, white-tailed tropicbird from Cousin Island in Seychelles, and Barau’s petrel from Reunion Island. It is also used to a lesser degree as a migration stop off point for lesser frigatebird travelling from breeding sites in the western Indian Ocean and non-breeding areas in South-East Asia. Between 30 and 40,000 individuals from these colonies are thought to use this area during the non-breeding season. The three major seabird breeding concentrations in the western Indian Ocean are Seychelles (3.4 million pairs), the Mozambique Channel (3.0 million pairs) and the Mascarene Archipelago (0.7 million pairs). Given that tracking studies show at least some of colonies in these regions use this area in the central Indian Ocean it seems likely that birds from a range of other non-tracked colonies also occur here during the non-breeding season (Le Corre et al. 2012).
C3: Importance for threatened, endangered or declining species and/or habitats Medium
Barau’s petrel is listed as Endangered on the IUCN Red List, it is an endemic breeder to the island of Reunion (BirdLife International, 2012).
C4: Vulnerability, fragility, sensitivity, or slow recovery Low
All seabird species are long-lived and slow at reproducing, leaving them prone to slow recovery after population declines. Shearwater species are susceptible to by-catch in fisheries, though known incidents of this are thought to be low within the tropical Indian Ocean and the described area. However, there is currently a lack of observer programmes to record by-catch events (Anderson et al., 2009).
C5: Biological productivity Low
Lévy et al. (2007) showed that a pronounced seasonal phytoplankton bloom appears in the central Indian Ocean during austral winter.
C6: Biological diversity Medium
Tropical seabirds rely on surface seizing and plunge diving to acquire prey, and very few are able to dive deeper than a few metres. Because epipelagic prey are distributed within the upper 50 metres of the water column, they are only accessible to seabirds when surface dwelling predators like tunas and dolphins pursue epipelagic prey and force them to flee toward the surface. Tropical seabirds take advantage of this phenomenon by frequently foraging over schools of tunas or dolphins to catch the evading prey. This interaction is so important for tropical seabirds that it has been termed a “near-obligate commensalism” between seabirds and marine top predators (Au and Pitman, 1986). At-sea surveys made in the western Indian Ocean show that most seabird of this region are associated with surface-dwelling predators (Jaquemet et al. 2004, 2005). Therefore it seems highly probable that this area is of importance for other top predators.
C7: Naturalness No information
Additional Information
The areas included here meet one or more of the BirdLife criteria for defining Important Bird Areas. (BirdLife International, 2010) BirdLife Important Bird Areas Criteria (BirdLife 2009, 2010) A1 Regular presence of threatened species A4ii >1% of the global population of a seabird A4iii >20,000 individuals (As per Ramsar) Rights and permissions Tracking data used in this analysis is property of the data owners, images provided here can be used with appropriate credits. Any request to publish these images elsewhere or to use the original tracking data will require permission, requests should be made to BirdLife International (science@birdlife.org) The data used to define this area are part of a regional tracking program leaded by M. Le Corre and funded by the Pew Environmental Group aiming at identifying important marine areas in the tropical Indian Ocean.