Monk Seal Fact Files

Mediterranean Monk Seal

(Monachus monachus)

Distribution and abundance

Thousands of islands, inaccessible coastlines, and a species that shies away from human contact have all conspired to make distribution and abundance assessments for the Mediterranean monk seal (Monachus monachus) an extraordinarily inexact science. Conventional wisdom, however, suggests that fewer than 600 individuals survive, making the Mediterranean monk seal Europe’s most endangered marine mammal.

The Mediterranean monk seal is “Critically Endangered (CR)” according to the IUCN Red List of Threatened Species (IUCN 2000, UNEP-WCMC 2005). A species is so listed, according to IUCN, “when it is facing an extremely high risk of extinction in the wild in the immediate future,” as defined by specific criteria (For further info, see: http://www.redlist.org/info/categories_criteria1994.html#categories).

Historically, Monachus monachus occupied a wide geographical range (see map below). Colonies were found throughout the Mediterranean, Marmara and Black seas. The species also frequented the Atlantic coast of Africa, as far south as Mauritania, Senegal and the Gambia, as well as the Atlantic islands of Cape Verde, Madeira, the Canary Islands and the Azores (Johnson & Lavigne 1999a, Johnson 2004).

Updated (2016) distribution map of Monachus monachus. [Go to interactive map]

More recently, however, the species has disappeared from most of its former range, with the most severe contraction and fragmentation occurring during the last century. Nations and island groups where the monk seal has been extirpated during the 20th century include France and Corsica, Spain and the Balearic Islands, Italy, Sardinia, Sicily and the Tuscan archipelago, as well as Egypt, Israel and Lebanon (UNEP/MAP 1994, Aguilar 1998). More recently, the species is also thought to have become effectively extinct in the Black Sea (Kiraç 2001). Despite sporadic sightings, Monachus monachus is also effectively extinct in the Sea of Marmara, along the Adriatic coasts and islands of Croatia, Sardinia, and the Mediterranean coasts of Morocco (Johnson 1998, Johnson & Lavigne 1999a, 1999b, Lavigne & Johnson 2001, Abdellatif Bayed, pers. comm. 2005).

Uncertainty also hangs over the survival of the monk seal in Tunisia, where the species has faced onslaughts in its last retreats by tourists and sports divers (Ouerghi et al. 2001).

Illustrating the inherent uncertainty of monk seal population estimates, a monk seal birth was reported in December 2004 in Sicily – the first recorded birth on the island in 30 years (Emanuele Coppola, pers. comm. 2004). It is unclear whether the species continued to inhabit Sicily during the intervening years unbeknown to researchers, or whether it recolonised the island from elsewhere.

In some cases, the reappearance of monk seals in areas from which they were previously considered eradicated – notably in Sardinia and Croatia most recently (Coppola 2003, Gomercic et al. 2005) – may be due to stragglers arriving from adjacent populations. Given favourable conditions in terms of habitat and food, it is thought possible that monk seals could re-establish themselves in such areas.

Eradicated from most of its former range, the Mediterranean monk seal is now mainly confined to two surviving populations, one occupying the Atlantic coast of northwest Africa, and the other, the northeastern Mediterranean.

Partly because of their own tendency to err on the side of caution, historically, biologists have consistently underestimated the numbers of monk seals populating the Mediterranean — offering some explanation as to why estimates have remained numerically stable over the last 30 years despite severe and undiminished threats (Cf. Ronald & Duguy eds. 1979 and Aguilar 1998).

Conversely, errors have also been known to creep into population estimates when biologists rely on old data. This has often resulted in monk seal colonies being placed in areas where they have been extinct for many years.

Predictably, absence of accurate population data has hampered the implementation of effective conservation actions (Forcada et al. 1999). Although sometimes subject to changing political climates, political instability and military sensitivity have also prevented research along some extensive reaches of the Mediterranean basin, particularly Algeria and Libya, and the coast of the disputed Western Sahara.

With question marks hanging over monk seal abundance in many regions and countries, the figures presented in the table below should be treated with caution.

Additional notes:

* Population estimates for Turkey were revised upwards in 2004. For further details, consult: Güçlüsoy, H., C.O. Kiraç, N.O. Veryeri and Y. Savas. 2004a. Status of the Mediterranean Monk Seal, Monachus monachus (Hermann, 1779) in the Coastal Waters of Turkey. E.U. Journal of Fisheries & Aquatic Sciences 21 (3-4): 201–210. [PDF 925KB]

** Italy and Sardinia remain at “0” despite recent sightings, because researchers have yet to identify occupied habitat.

*** Abdellatif Bayed, personal communication 2005.

**** Approximation only. Following the mass mortality that struck the world’s largest surviving monk seal colony in the Western Sahara in 1997, 103 individuals were estimated to survive (mean estimate. 95% CI: 77 – 148, Forcada et al. 1999), down from 300. These estimates are generally considered more reliable than those obtained elsewhere since they relied upon clearly-defined photo-identification procedures, often impractical elsewhere. New estimates of 150 individuals are based on interpretations of evidence by researchers – counts of seals at low tide in breeding caves, increasing beach counts, and decreasing mortalities – but have not been confirmed by capture-recapture methods (that compare data from different sample frames).

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