|Scientific Name:||Mobula mobular|
|Species Authority:||(Bonnaterre 1788)|
Raia mobular Bonnaterre, 1788
|Taxonomic Notes:||Since expert examination is needed to distinguish M. mobular from M. japanica (the spinetail devilray), a circumtropical species also known from the tropical Atlantic (Notarbartolo di Sciara 1987), past reports of giant devilrays from the Atlantic may have been due to incorrect identification of spinetail devilrays.|
|Red List Category & Criteria:||Endangered A2d ver 3.1|
|Assessor(s):||Notarbartolo di Sciara, G., Serena, F. & Mancusi, C.|
|Reviewer(s):||Stevens, G., Walls, R. & Kemp, J.R.|
|Facilitator/Compiler(s):||Walls, R., Frazer, K. & Dulvy, N.|
Giant Devil Ray (Mobula mobular) is the largest species of the genus Mobula and has a very low reproductive capacity (i.e., giving birth to a single large pup at unknown intervals). Its geographic range is limited to the Mediterranean Sea and possibly adjoining North Atlantic waters. This species is taken as bycatch in many different fisheries (most notably in pelagic driftnets) in several locations within its range. Giant Devil Ray was previously assessed as Endangered in 2006, given its high bycatch mortality, limited reproductive capacity and restricted range. More recently, it was discovered that this species is the targeted catch of a massive purse seine fishery in the Levantine Sea that operates on a seasonal basis. Although the increased control and phasing out of illegal pelagic driftnets has greatly reduced fishing pressure over the last eight years, the significant threat imposed by this fishery in the eastern Mediterranean Sea suggests that this species is still at risk of overexploitation. A population reduction of at least 50% over three generations (60 years) is suspected based on the high mortality rate of this species, its low ability to recover from large population declines owing to its slow life history, and the lack of change in fishing pressure that the species is subject to. For this reason, Giant Devil Ray is assessed as Endangered in European waters under criteria A2d.
|Range Description:||This species occurs throughout the Mediterranean Sea, and possibly in the nearby Northeast Atlantic, but is absent from the Black Sea. Outside the Mediterranean, it has been reported from the coast of northwest Africa (Morocco to Senegal), the Canary Islands, Madeira, the Azores, Portugal, and as a vagrant off southern Ireland (Notarbartolo di Sciara 1987, Serena 2005, Ebert and Stehmann 2013). However, close-up expert examination (e.g., morphometric comparison, tooth morphology) is needed to distinguish Giant Devil Ray (Mobula mobular) from Spinetail Devil Ray (Mobula japanica). Spinetail Devil Ray is a circumtropical species also known from the North Atlantic (Notarbartolo di Sciara 1987), hence, past reports of Giant Devil Ray from the Atlantic may have referred to incorrectly identified Spinetail Devil Ray. While the presence of Giant Devil Ray outside of the Mediterranean Sea must be considered uncertain for now, precise diagnoses based on morphological details (e.g., Adnet et al. 2012) and genetic analyses will eventually clarify the extent of this species’ range.|
Native:Albania; Algeria; Bosnia and Herzegovina; Croatia; Cyprus; Egypt (Egypt (African part), Sinai); France (Corsica, France (mainland)); Gibraltar; Greece (East Aegean Is., Greece (mainland), Kriti); Israel; Italy (Italy (mainland), Sardegna, Sicilia); Lebanon; Libya; Malta; Montenegro; Morocco; Palestinian Territory, Occupied; Portugal; Slovenia; Spain (Baleares, Spain (mainland)); Syrian Arab Republic; Tunisia; Turkey (Turkey-in-Asia, Turkey-in-Europe)
|FAO Marine Fishing Areas:||
Atlantic – eastern central; Atlantic – northeast; Mediterranean and Black Sea
|Range Map:||Click here to open the map viewer and explore range.|
|Population:||The population trend is suspected to be decreasing. With the exception of recent results from an aerial survey in the south-central Adriatic Sea, where a population of 1,595 individuals (coefficient of variation 25%) was estimated (Fortuna et al. 2014), there are no overall regional population estimates for this species. It appears to occur in low densities (with group sizes of one to four individuals) throughout its range, although a recent episode in which these rays were mass captured off Gaza (see Threats section) indicates that the species may occasionally occur in large aggregations. The generation length of this species is suspected to be around 20 years, based on the fact that Manta alfredi's is 25 years. A population reduction of at least 50% over three generations (60 years) is suspected for the population of this species.|
|Habitat and Ecology:||
This species occurs both in neritic (Notarbartolo di Sciara and Serena 1988, Bradaï and Capapé 2001, Scacco et al. 2009, Holcer et al. 2012) and offshore (Canese et al. 2011) waters ranging in depth from a few tens of metres to several thousand metres. Like all devil rays, this species is known as an epipelagic batoid, but it can dive up to 600−700 m (Canese et al. 2011).
Devil rays are aplacental, live-bearing matrotrophs (i.e., the neonate receives nourishment from uterine milk secretion; Wourms 1977). They give birth to a single large pup. A term embryo of this species was born from a specimen caught in the northern Tyrrhenian Sea in late spring of 1986 (Notarbartolo di Sciara and Serena 1988). The disc width was 166 cm and it weighed 35 kg, making it the largest devil ray embryo on record (Notarbartolo di Sciara 1987). Observations of Notarbartolo di Sciara and Serena (1988) suggest that this species gives birth during the summer in the northern Mediterranean Sea and that a pup could exceed 160 cm disc width at birth. The gestation period is unknown, but it could be one of the longest among Chondrichthyes (cartilaginous fish).
|Use and Trade:||The species is not utilised nor traded commercially.|
The only known directed fishery for this devil ray was recently discovered in the Levantine Sea. Purse seines are used by Palestinian fishermen in late winter (Couturier et al. 2013), and are likely unsustainable.
This species is taken incidentally in several fisheries (Baino et al. 2012), including: pelagic driftnets (Muñoz-Chàpuli et al. 1994, Celona 2004, Akyol et al. 2005), purse seines (Notarbartolo di Sciara and Bianchi 1998, Hemida et al. 2002), trammel nets (Bradaï and Capapé 2001, Holcer et al. 2012), longlines (Orsi Relini et al. 1999, Holcer et al. 2012), bottom trawls (Bauchot 1987, Bradaï and Capapé 2001, Hemida et al. 2002), pelagic paired trawls (Scacco et al. 2009), fixed tuna traps (Boero and Carli 1979), and hand harpoon (Celona 2004). Pelagic driftnets are banned in the Mediterranean Sea by a number of European, General Fisheries Commission for the Mediterranean, and International Commission for the Conservation of Atlantic Tuna regulations; however, significant illegal activities still occur (e.g., in Southern Italy, Morocco and Turkey) and these are likely a continued source of mortality for the species, particularly if trade demand for their gill plates increases.
The impacts of habitat degradation on this species are unknown. Given its low trophic position, high levels of contamination from organochlorine compounds or trace elements are unlikely. However, as an epipelagic species it is particularly vulnerable to oil spills, ingestion of microplastics, and disturbance from the high level of maritime traffic.
This species is usually discarded when caught as bycatch but occasionally landed and marketed (e.g., in the southern Adriatic coast of Apulia; Relini et al. 2010). In March 2013, the media provided evidence of massive catches of Giant Devil Rays off the Gaza Strip (Levantine Sea). In a single episode, over 500 Giant Devil Rays, including some sub-adults, were captured with a local type of purse seine, called “shinshula”, landed and butchered on the beach for local human consumption (Couturier at al. 2013). Depending on the size of the total population and the frequency of such events, this pattern of exploitation is likely unsustainable.
Giant Devil Ray is included in Annex II 'List of endangered or threatened species' to the Protocol concerning Special Protected Areas and Biological Diversity in the Mediterranean of the Barcelona Convention, which came into force in 2001, and in Annex II ‘Strictly protected fauna species’ to the Bern Convention. In 2012, parties to the Barcelona Convention agreed that this species cannot be retained on board, transshipped, landed, transferred, stored, sold, displayed or offered for sale, and must be released unharmed and alive, to the extent possible, pursuant to Recommendation GFCM/36/2012/1 (FAO 2012).
The Pelagos Sanctuary for Mediterranean Marine Mammals, where the driftnet ban is now effective, affords umbrella protection to this species.
Conservation actions recommended for the future include:
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Akyol O., Erdem M., Unal V., Ceyhan T. 2005. Investigations on drift-net fishery for swordfish (Xiphias gladius L.) in the Aegean Sea. Turkish Journal of Veterinary and Animal Science 29: 1225-1231.
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Boero, F. and Carli, A. 1979. Catture di Elasmobranchi nella tonnarella di Camogli (Genova) dal 1950 al 1974. Boll. Mus. Ist. Biol. Univ. Genova 47: 27-34.
Bradai, M.N. and Capapé, C. 2001. Captures du diable de mer, Mobula mobular, dans le Golfe de Gabés (Tunisie meridionale, Méditerranée centrale). Cybium 25(4): 389–391.
Canese, S., Cardinali, A., Romeo, T., Giusti, M., Salvati, E., Angiolillo, M. and Greco, S. 2011. Diving behaviour of Giant Devil ray in the Mediterranean Sea. Endangered Species Research 14: 171-176.
Celona, A. 2004. Catture ed avvistamenti di mobula, Mobula mobular (Bonnaterre, 1788) nelle acque dello Stretto di Messina . Annales 14: 11-18.
Couturier, L.I.E., Bennett, M.B. and Richardson, A.J. 2013. Mystery of giant rays off the Gaza strip solved. Oryx 47(4): 479-482.
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Fortuna, C.M., Kell, L., Holcer, D., Canese, S., Filidei, E., Mackelworth, P. and Donovan, G. 2014 . Summer distribution and abundance of the Giant Devil Ray (Mobula mobular) in the Adriatic Sea: baseline data for an iterative management framework. Scientia Marina 78(2): 227-237.
Hemida, F., Mehezem, S. and Capapé, C. 2002. Captures of the Giant Devil ray, Mobula mobular Bonnaterre, 1788 (Chondrichthyes: Mobulidae) off the Algerian coast (southern Mediterranean) . Acta Adriatica 43(2): 69-76.
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|Citation:||Notarbartolo di Sciara, G., Serena, F. & Mancusi, C. 2015. Mobula mobular. The IUCN Red List of Threatened Species. Version 2015.2. <www.iucnredlist.org>. Downloaded on 28 August 2015.|