Mobula birostris 

Scope: Global
Language: English

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Taxonomy [top]

Kingdom Phylum Class Order Family
Animalia Chordata Chondrichthyes Rajiformes Mobulidae

Scientific Name: Mobula birostris (Walbaum, 1792)
Common Name(s):
English Giant Manta Ray, Chevron Manta Ray, Oceanic Manta Ray, Pacific Manta Ray, Pelagic Manta Ray
Spanish Manta Cornuda, Manta Diablo, Manta Gigante, Manta Raya, Manta Voladora
Manta birostris (Walbaum, 1792)
Manta hamiltoni Hamilton & Newman, 1849)
Raja birostris Donndorff, 1798
Taxonomic Source(s): Walbaum, J.J. 1792. Petri Artedi Sueci Genera piscium. In quibus systema totum ichthyologiae proponitur cum classibus, ordinibus, generum characteribus, specierum differentiis, observationibus plurimis. Redactis speciebus 242 ad genera 52. Ichthyologiae, pars iii. Artedi Piscium 3: 1-723.
Taxonomic Notes: Previously, the genus Manta was considered monotypic by most authors. The genus was recently re-evaluated and split into two species, the Reef Manta Ray (Manta alfredi) and the Giant Manta Ray (Manta birostris) (Marshall et al. 2009). Genetic evidence further confirms the existence of two separate species (Kashiwagi et al. 2008, Ito and Kashiwagi 2010). Both species have worldwide distributions. Manta species are sympatric in some locations and allopatric in other regions (Kashiwagi et al. 2011).

Reports are often mixed as the splitting of the genus occurred very recently (2009). Historical reports can often be confusing as well without adequate descriptions or photographs. Care should be taken when using reports or accounts of the Giant Manta Ray that they are not referring to the Reef Manta Ray (or vice versa).

Melanistic (black) and leucistic (white) colour morphs occur in both species of Manta (Marshall et al. 2009). Variant colour morphs often contributed an added degree of confusion when attempting to discriminate between species of Manta in the field or in photographs, especially when close examination was not possible. It should be noted that these colour morphs could be a possible source of error, resulting in mis-identifications in future studies or surveys of distribution.

It has been suggested by Marshall et al. (2009) that a third, putative species, Manta cf. birostris, in the Atlantic may be distinct from the Giant Manta Ray. This putative species shares some characteristics with the Giant Manta Ray, such as a large maximum disc width and the presence of a distinct, reduced caudal spine. However, from the limited specimens and photographs examined, clear differences exist between Manta cf. birostris and the Giant Manta Ray including dissimilar denticle morphology and distribution, intermediary dentition and, most noticeably, differences in dorsal and ventral colouration. While Manta cf. birostris occurs in sympatry with the Giant Manta Ray in parts of the Atlantic and Caribbean, there is some evidence that differences in fine-scale habitat selection and seasonal habitat use may occur in some locations (Bigelow and Schroeder 1953, Notarbartolo-di-Sciara and Hillyer 1989). At present there is not enough empirical evidence to warrant the separation of a third species of Manta.

Manta rays are often confused with rays of the genus Mobula, and care should be used to ensure reports of mantas are actually of Manta and not its sister genus.

Assessment Information [top]

Red List Category & Criteria: Vulnerable A2abd+3bd+4abd ver 3.1
Year Published: 2018
Date Assessed: 2010-11-01
Assessor(s): Marshall, A., Bennett, M.B., Kodja, G., Hinojosa-Alvarez, S., Galvan-Magana, F., Harding, M., Stevens, G. & Kashiwagi, T.
Reviewer(s): Ebert, D.A. & Kyne, P.M.
The Giant Manta Ray (Mobula birostris), the largest living ray, has a circumtropical and also semi-temperate distribution throughout the world’s major oceans, however within this broad range, actual populations appear to be sparsely distributed and highly fragmented. This is likely due to the specific resource and habitat needs of this species. Overall population size is unknown, but subpopulations appear to be small (about 100–1,000 individuals). Only recently separated from the Reef Manta Ray (M. alfredi), little is currently known about this ray except that it is elusive and potentially highly migratory.

The degree of interchange of individuals between subpopulations is unclear but is assumed to be low as there are currently no data that support such interchange despite active efforts to do so. As such, the decline of these small subpopulations may result in regional depletions or extinctions with the reduced possibility of successful recolonization. To aggravate this situation, this species has a very conservative life history with an extremely low reproductive output (one pup per litter). These biological constraints would also contribute to its slow or lack of recovery from population reductions.

Currently this species has a high value in international trade and directed fisheries exist that target this species in what is certain to be unsustainable numbers. Artisanal fisheries also exist that target this species for food and medicine. Individuals are also taken as bycatch in everything from large-scale fisheries to shark control programs/bather protection nets.

The rate of population reduction appears to be high in several regions, as much as 80% over the last three generations (approximately 75 years), and globally a decline of 30% is strongly suspected. Sustained pressure from fishing (both directed and bycatch) has been isolated as the main cause of these declines. Certain monitored subpopulations appear to have been depleted, such as in the Philippines, Indonesia, and parts of Mexico and are believed to be decreasing in other areas such as India and Sri Lanka as a result of sustained pressure from fishing. Of particular concern is the targeting of this species at critical habitats or well-known aggregation sites where numerous individuals can be targeted with relatively low catch-per-unit-effort.

Dive tourism involving this species is a growing industry and it has been demonstrated that sustainable tourism significantly enhances the economic value of such species in comparison to short-term returns from fishing. Tourism related industries can also negatively impact individual behaviour, entire populations and critical habitat for this species, thus the responsible development of these industries is recommended.
Previously published Red List assessments:

Geographic Range [top]

Range Description:Circumglobal in tropical and temperate waters, this species has a widespread distribution. The Giant Manta Ray has been documented to occur as far north as southern California and New Jersey on the United States west and east coasts, respectively, Mutsu Bay, Aomori, Japan, the Sinai Peninsula, Egypt and the Azores Islands in the Northern Hemisphere and as far south as Peru, Uruguay, South Africa and New Zealand in the Southern Hemisphere.

In a few locations, including Mozambique, the Giant Manta Ray is sympatric with the Reef Manta Ray. When they occur together these species typically exhibit different habitat use and movement patterns (Marshall et al. 2009, Kashiwagi et al. 2011).

The Giant Manta Ray appears to be a seasonal visitor to coastal or offshore sites. While this species seems more solitary than the Reef Manta Ray, Giant Manta Rays are often seen aggregating in large numbers to feed, mate, or clean. Sightings of these giant rays are often seasonal or sporadic but in a few locations their presence is a more common occurrence. Observations of the Giant Manta Ray at aggregation sites such as the Similan Islands, Thailand; northeast North Island, New Zealand; Laje de Santos Marine Park, Brazil; Isla de la Plata, Ecuador; and Isla Holbox, Mexico, indicate that this species is a regular seasonal visitor, with sightings only during specific, predictable times of the year (Duffy and Abbott 2003, Luiz et al. 2009, A. Marshall pers. obs. 2011).

Observations of the Giant Manta Ray frequenting remote seamounts in Isla Socorro, Mexico, Malpelo, Columbia and off some remote islands (Cocos Island, Costa Rica; Galápagos, Ecuador; Laje de Santos, Brazil) show a degree of philopatry to these sites but also indicate that these mantas make migrations away from these areas during parts of the year (Rubin 2002, Luiz et al. 2009, A. Marshall unpubl. data 2011). In other areas, such as southern Mozambique, the Giant Manta Ray is seen sporadically throughout the year although individuals are not commonly re-sighted over time (Marshall 2009).
Countries occurrence:
Australia (Western Australia); Belize; Bermuda; Bonaire, Sint Eustatius and Saba (Saba, Sint Eustatius); Brazil; Cayman Islands; Christmas Island; Colombia (Malpelo I.); Costa Rica (Cocos I., Costa Rica (mainland)); Cuba; Curaçao; Djibouti; Dominican Republic; Ecuador (Galápagos); Egypt; El Salvador; French Guiana; Guatemala; Guyana; Honduras (Honduras (mainland)); India (Andaman Is., Andhra Pradesh, Goa, Gujarat, Kerala, Maharashtra, Tamil Nadu); Indonesia (Bali, Papua, Sumatera); Jamaica; Japan; Kenya; Malaysia; Maldives; Mexico (Baja California, Baja California Sur, Quintana Roo, Revillagigedo Is., Sinaloa, Yucatán); Mozambique; Myanmar (Coco Is., Myanmar (mainland)); New Zealand (North Is.); Nicaragua (Nicaragua (mainland)); Nigeria; Northern Mariana Islands; Panama; Peru; Philippines; Portugal (Azores, Madeira); Saint Martin (French part); Senegal; Seychelles (Seychelles (main island group)); Sint Maarten (Dutch part); South Africa (Eastern Cape Province, KwaZulu-Natal, Western Cape); Spain (Canary Is.); Sri Lanka; Sudan; Taiwan, Province of China (Taiwan, Province of China (main island)); Tanzania, United Republic of; Thailand; Trinidad and Tobago; United States (Alabama, Arkansas, California, Delaware, Florida, Georgia, Hawaiian Is., Louisiana, Maryland, Mississippi, New Jersey, North Carolina, South Carolina, Texas, Virginia); Uruguay; Venezuela, Bolivarian Republic of (Venezuela (mainland))
FAO Marine Fishing Areas:
Atlantic – western central; Atlantic – eastern central; Atlantic – northeast; Atlantic – northwest; Atlantic – southeast; Atlantic – southwest; Indian Ocean – western; Indian Ocean – eastern; Pacific – southeast; Pacific – southwest; Pacific – eastern central; Pacific – northwest; Pacific – western central
Additional data:
Lower depth limit (metres):1000
Range Map:Click here to open the map viewer and explore range.

Population [top]

Population:This species is not regularly encountered in large numbers and, unlike the Reef Manta Ray do not often appear in large schools (>30 individuals) when feeding. Overall they are encountered with far less frequency than the smaller species Mobula alfredi, the Reef Manta Ray, despite having a larger distribution across the globe.

Due to the global nature of their individual distributions, absolute population sizes will always be difficult to assess. Currently, the overall total global population sizes of both these species are unknown, but subpopulations appear, in most cases, to be small (less than 1,000 individuals). The degree of interchange of individuals between subpopulations is unclear but is assumed to be low, as there are currently no data that support such interchange, despite active efforts to do so (A. Marshall et al. unpubl. data 2011).

Photo-identification studies at major aggregation sites in southern Mozambique (Marshall 2009); southern Brazil (Luiz et al. 2009); Revillagigedo Islands, Mexico (Rubin 2002); the Ogasawara Islands, Japan (Yano et al. 1999a, Kashiwagi et al. 2010); the Maldives (G. Stevens unpubl. data 2011); Isla Holbox, Mexico (S. Hinojosa-Alvarez unpubl. data 2010); Isla de la Plata, Ecuador (M. Harding unpubl. data 2010) have databases of less than 300 individuals, with many of these studies having been underway for the last 10–20 years. A semi-exhaustive study of Japan-wide photographic records confirmed that the known main aggregation in Ogasawara Islands (42 known individuals during 1995–1998 study) represents a part of a fairly isolated population (Kashiwagi et al. 2010).

A mark-recapture population study in southern Mozambique over five years from 2003 to 2008 estimated the local population during that time to be 600 individuals (Marshall 2009). Flight surveys and re-sightings data of individuals at Isla Holbox, Mexico have estimated that roughly 100 manta rays use this area during every season (S. Hinojosa-Alvarez unpubl. data 2010).

While the Giant Manta Ray is widely distributed and appears to be a migratory species, regional populations appear to be small considering the scale of their habitat. Individuals most commonly show a degree of site fidelity to specific regions, as well as critical habitats within them, such as cleaning stations and feeding sites. Preliminary satellite tracking studies and international photo-identification matching projects have suggested a low degree of interchange between populations.

While there is a distinct paucity of information on population numbers or trends, local populations are likely to be in decline in areas where they are fished, or are under threat from anthropogenic influences e.g., India/Sri Lanka (Pillai 1998, Anderson et al. 2010), Indonesia (White et al. 2006), Philippines (Alava et al. 2002) and the west coast of Mexico where encounter rates have dropped significantly over the last five years or anthropogenic mortality has been elevated.

Overall, the rate of population reduction appears to be high in several regions, up to as much as 80% over the last three generations (approximately 75 years), and globally a decline of >30% is strongly suspected.

Historical fisheries data and reported declines in population numbers:

A study in the Pamilacan Island, Philippines reported that up to 1,000 rays, particularly manta rays (Giant Manta Ray) and a few other species of the genus Mobula, were harvested per year in directed fisheries. Over 35 villages reportedly participated in this fishery. Seasons that started in September and went through until May or June the following year, peaked in the November and December months. Manta rays were fished with gaff hooks, hand spears, harpoons, and gillnets. Although these targeted fisheries were reported to have been active for generations (some claiming since the 1800s and others since the mid 1950s), interviewed fishermen noted that the catch-per-unit-effort (CPUE) and overall number of rays in the area has declined significantly in recent times. Record landings were reported in the 1960s (Alava et al. 2002).

Japanese sports divers suggest that the population of manta rays at one site in the Sulu Sea, Philippines (probably part of the same population fished at Pamilacan Island, Philippines) fell by one half to two-thirds in seven years from the end of the 1980s (M. Nishitani pers. comm.). Fishermen from this region reported a decrease in their CPUE and number of landings since the 1960s.

The Giant Manta Ray once occurred in large numbers along the west coast of Mexico and Baja California. The species appears to be rare after several decades of fishing. Manta rays were commonly used as shark bait, for local consumption and for export as ‘fake scallops’ (Booda 1984, Rubin 2002). A specific study of the fisheries (predominately gillnets, harpoons and baited hooks from engine powered fibreglass boats) in La Paz from 1981–1984 targeting rays in waters from 10–200 m revealed that 94% of the catch were mobulid rays, including manta rays in small numbers (Notarbartolo-di-Sciara 1987).

In the Yucatan Peninsula, Central America, manta rays were used as bait for shark fisheries, but recent legislation has prohibited this use. These actions have seemingly prevented the continued decrease of the species in Mexican Caribbean waters.
Current Population Trend:Decreasing
Additional data:

Habitat and Ecology [top]

Habitat and Ecology:The Giant Manta Ray occurs in tropical, sub-tropical and temperate waters of the Atlantic, Pacific and Indian Oceans. Commonly sighted along productive coastlines with regular upwelling, oceanic island groups and particularly offshore pinnacles and seamounts. The Giant Manta Ray is commonly encountered on shallow reefs while being cleaned or is sighted feeding at the surface inshore and offshore. It is also occasionally observed in sandy bottom areas and seagrass beds.

A global investigation of major aggregation sites revealed that the Giant Manta Ray may be a more oceanic and a more migratory species than the Reef Manta Ray (A. Marshall et al. unpubl. data). Rare or seasonal sightings of the Giant Manta Ray at locations such as northern New Zealand (Duffy and Abbott 2003), southern Brazil (Luiz et al. 2009) and Uruguay (Milessi and Oddone 2003), the Azores Islands, the Similan Islands, Thailand (A. Marshall unpubl. data 2011) and the eastern coast of the United States (Bigelow and Schroeder 1953), suggests that this species undergoes significant seasonal migrations.

Despite these data, preliminary satellite tracking studies and international photo-identification matching projects have suggested a high degree of fragmentation between regional populations of this species, suggesting that movements across ocean basins may be rare. Satellite tracking results have been able to reveal that the Giant Manta Ray is capable of large migrations (over 1,100 km straight line distance) and have monitored individual movements across international borders, across large bodies of water, and into international waters (A. Marshall et al. unpubl. data 2011, R. Rubin pers. comm. 2009). Satellite tracking studies using archival PAT tags have registered movements of the Giant Manta Ray from Mozambique to South Africa (a distance of 1,100 km), from Ecuador to Peru (190 km), from the Yucatan, Mexico into the Gulf of Mexico (448 km). This species is capable of deep dives and has been both seen at depth and tracked down to depths exceeding 1,000 metres (A. Marshall et al. unpubl. data 2011).

The Giant Manta Ray reaches disc widths (DW) of at least 700 cm, with anecdotal reports up to 910 cm DW (Compagno 1999, Alava et al. 2002). Size at maturity for the Giant Manta Ray may vary slightly throughout its range, but males in southern Mozambique mature at approximately 400 cm DW while females appear to mature well over 400 cm DW (Marshall 2009). In Indonesia, data from fisheries dissections suggest that in that region male Giant Manta Rays mature at 375 cm DW, while females may mature by approximately 410 cm DW (White et al. 2006).

The Giant Manta Ray appears to be a relatively long-lived species. Although the actual longevity of the species remains unknown, photographic databases have re-sighted individuals up to a 20 year period (Rubin 2002, G. Kodja unpubl. data 2010). Natural mortality is thought to be low (other than in juveniles), although limited predation from large sharks does occur (Marshall 2009).

Generation time is suspected to be 25 years based on conservative estimates of life history parameters from the Reef Manta Ray. Female mantas are thought to mature at 8–10 years of age and longevity is estimated to be at least 40 years. Generation time is the average age of adults which can be approximated as halfway between age at first maturity and maximum age. Thus female mantas may be actively breeding for 30 years and the age at which 50% of total reproductive output is achieved would be approximately 24–25 years.

Copulation has been documented off the Ogasawara Islands, Japan and is believed to occur in the summer months (Yano et al. 1999b). Two pregnant individuals have been registered and photographed in southern Mozambique although a breeding season at this location has not been established (Marshall 2009). There is little information on the reproductive biology or ecology of this species although reports of litter size are consistently of a single offspring (Coles 1916, Beebe and Tee-Van 1941, Bigelow and Schroeder 1953).
For further information about this species, see 198921_Manta_birostris.pdf.
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Generation Length (years):25
Movement patterns:Full Migrant

Use and Trade [top]

Use and Trade:

The meat is often sold as food, the liver for medicine and branchial filter plates (gill rakers) from Mobula spp enter international trade and fetch high prices in Asia where they are used for traditional Chinese medicine (Zhongguo yao yong dong wu zhi xie zuo zu bian zhu 1983). Meat from the Giant Manta Ray is also often used for shark bait or attractant in Mexico. Limited use of epidermis for leather products has been verified.

Giant Manta Rays are sometimes caught and transported to aquariums for use in display tanks. The Georgia Aquarium, the Atlantis Resort in the Bahamas, and the Lisbon Aquarium have had or are presently housing wild caught Giant Manta Rays in their exhibits. Some of these captive animals have been released into the wild.

Threats [top]

Major Threat(s): The main threat to both Mobula birostris and M. alfredi is fishing, whether targeted or incidental. Manta rays are currently killed or captured by a variety of methods including harpooning, netting and trawling. These rays are easy to target because of their large size, slow swimming speed, aggregative behaviour, predictable habitat use, and lack of human avoidance.

Manta rays have a high value in international trade markets. Their gill rakers are particularly sought after and are used in Asian medicinal products. This market has resulted in directed fisheries for manta rays which are currently targeting these rays in unsustainable numbers. Over 1,000 manta rays are caught per year in some areas (Alava et al. 2002, Dewar 2002, White et al. 2006, C. Anderson and G. Stevens pers. obs.). Artisanal fisheries also target both species for food and local products (Essumang 2010, Marshall et al. 2011).

Aside from directed fisheries, manta rays are also incidentally caught as bycatch in both large-scale fisheries and small netting programs such as shark control bather protection nets (Carlson and Lee 2000, Young 2001). In some populations, such as the ones identified at Isla de la Plata, Ecuador, Laje de Santos, Brazil, and the Similan Islands, Thailand, high percentages of all individuals encountered or identified have evidence of entanglement or are dragging lines or nets (A. Marshall unpubl. data 2011).

As a result of sustained pressure from fishing (both directed and bycatch) certain monitored subpopulations appear to have been rapidly depleted (e.g., Gulf of California, Mexico; Indonesia; and, Philippines (Anon 1997, Alava et al. 2002, White et al. 2006)). Targeting either species of Manta at critical habitats or aggregation sites, where individuals can be caught in large numbers in a short time frame, is a particular threat. Regional populations of both species appear to be small, and localized declines are unlikely to be mitigated by immigration. This situation is exacerbated by the conservative life history of these rays, which constrain their ability to recover from a depleted state.

Cryptic threats such as mooring line entanglement and boat strikes can also wound manta rays, decrease fitness or contribute to non-natural mortality (Deakos et al. 2011). Many other threats have been postulated and identified such as habitat degradation, climate change, pollution (e.g., from oil spills), ingestion of micro plastics and irresponsible tourism practices.

Known directed fisheries:

Reported World Catch
Manta and devil ray catches increased from 900 tonnes to over 3,300 tonnes between 2000–2007 (FAO 2009, Lack and Sant 2009).

Trade-driven Fisheries
Manta rays, predominately the Giant Manta Ray, are currently taken in fisheries that have transitioned from bycatch fisheries to directed fisheries, with the birth of a market for manta ray products in Asia.

Chondrichthyan landings from drift gillnets were examined at four different sites (a total of 263 sampling days) in Indonesia from 2001 until 2005. Mobulid rays including manta rays were commonly represented in the catch, which was estimated to be approximately 4,110 individuals annually, a biomass of approximately 544 tonnes of which manta rays (Giant Manta Ray) comprised 13.7% (White et al. 2006). Individual manta rays were worth up to $200 in the early 2000s. Dried filter plates were being exported to Hong Kong, Taiwan and Singapore (for up to US$30 per dry kilo) (White et al. 2006).

Manta rays (predominately the Giant Manta Ray) are taken in significant numbers as bycatch in the Pakistani, Indian and Sri Lankan gillnet fisheries, where they are used as shark bait, for human consumption and their branchial filaments are sold to Asian buyers (Anderson et al. 2010, P. Hilton pers. comm. 2011, G. Stevens unpubl. data 2010).

Artisanal Fisheries
Manta rays are caught in artisanal fisheries in Tanzania on longlines and in trawls. The meat is typically dried and consumed (Bianchi 1985, Iddawi and Stanley 1999, N. Iddawi, S. Yahya and S. Semesi pers. comm. 2010, A. Marshall unpubl. data 2011).

Both species of Manta (but predominately the Reef Manta Ray) are caught in artisanal fisheries in southern Mozambique for consumption. Manta rays are typically harpooned but also caught in nets with motorized boats. Approximately 50 individuals are taken per annum from a 50 km stretch of coastline (A. Marshall unpubl. data).

Isolated reports of fishing for mantas have continued in the Gulf of California. Artisanal pelagic gillnet fishermen throughout the Gulf of California have been observed to retain mantas as bait as well as utilize landed specimens for personal consumption and sale.

There is a seasonal fishery for manta rays along the Ghanaian coastline, particularly in Dixcove. Manta rays are targeted in this region for local food (Essumang 2010).

Bycatch fisheries
Manta rays are caught in gillnet and purse seine fisheries as well as netting programs throughout their distribution. Specific cases are outlined below:

Giant Manta Rays are caught in small numbers as bycatch in the European purse seine tuna fishery operating in the Atlantic Ocean. Observer data from 2003-2007, which corresponded to 2.9% coverage, recorded 11 individuals landed, a number that represented 17.8% of the total ray bycatch (Amande et al. 2010).

Incidental catches of manta rays in the protective shark nets off the beaches of KwaZulu-Natal, South Africa, peak in the summer months (49% of the total annual catch), although manta rays are caught throughout the year (Young 2001). Manta rays (both species but predominately the Reef Manta Ray) comprised 16.9% of the total historical batoid catches from these nets, with a mean annual catch of 60 individuals and an overall 33.7% mortality rate (Young 2001).

Giant Manta Rays are caught as bycatch or are killed in fisheries along the west coast of Thailand and Myanmar, including within the Similans National Park where evidence suggests that a high proportion of individuals visiting the area have been entangled by fishing line or nets. Incidental kills have also been reported in fishing nets, tackle and ghost nets (A. Marshall unpubl. data 2011).

Giant Manta Rays are not generally directly targeted in Ecuador, although shark and ray catch data collected by the Subsecretaria de Recursos Pesqueros show occasional incidental capture and one small directed fishery since the mid-eighties. Many manta rays in the aggregation site around Isla de la Plata show damage received from fishing equipment, which occurs when artisanal fishermen use trawling tackle illegally within the Machalillia National Park boundaries to fish for seasonal aggregations of Wahoo (Acanthocybium solandri) which coincide with the seasonal aggregation of Giant Manta Rays (M. Harding unpubl. data 2010).

Although manta rays are not directly targeted by fisheries in southeastern Brazil, several reports of Giant Manta Rays being captured as bycatch show that local fishing poses a threat to manta rays (Zerbini and Kotas 1998). The Brazilian government is currently promoting a policy to boost commercial fisheries in the area, through financial incentives, raising concerns on the future of that manta ray population. Reports of individuals entangled within discarded fishing gear (e.g., ‘ghost nets’) are not uncommon (G. Kodja unpubl. data 2010). The main aggregation site for the Giant Manta Ray is located close to the Port of Santos, Latin America’s largest seaport, increasing the risk of ship strikes.

Surveys made of the bycatch from 52 sets from the shark drift net fishery off Georgia and east Florida, USA from 1992–1995 included 148 rays, 14 of which were recorded as being the Giant Manta Ray (Trent et al. 1997). Another study of the bycatch in the directed shark drift gillnet fishery off the east coast of Florida and Georgia, which was set 4.8 km offshore in EEZ waters from 1998–1999, revealed that manta rays are still occasionally caught in this fishery (Carlson and Lee 2000).

Fisheries bycatch data collected from the U.S. tuna purse seine fishery in the central-western Pacific in 1999 listed the Giant Manta Ray amongst the species caught with a set frequency of 1.5%. A total of 18 mantas were caught (1.14 t) during the observed period, 100% of which was discarded (Coan et al. 2000).

Conservation Actions [top]

Conservation Actions: United States:  In 2009, the Governor of Hawaii signed House Bill 366 creating Act 092(09) establishing criminal penalties and administrative fines for knowingly killing or capturing manta rays within State waters. This makes Hawaii the first state in the US union to protect manta rays. There have never been fisheries for manta rays in Hawaii, but this bill will protect all Manta species living in or passing through the island group from future fishing pressure.

Republic of Maldives:  Since June 1995 there has been an export ban on all ray species and their body parts, effectively preventing any commercial fisheries from arising in this country, which has never targeted manta rays for local use in significant numbers. Furthermore, in June 2009 the Maldivian Government announced the creation of two new marine protected areas (MPAs), specifically identified for protection because of their importance as areas of critical habitats for the Maldives population of Reef Manta Ray and the occasional transient Giant Manta Ray.

Philippines:  Fishing of manta rays was banned in 1998, but this ban was lifted in 1999 due to pressure from fishermen and lack of data on the fishery. During a year-long survey, from March 2002 to March 2003, 156 manta rays (the Giant Manta Ray) were caught, mostly in the months from November to January. Since the study, the ban has been re-established for manta rays. Mantas are now reported to be rare in the Philippines, especially around the Bohol Sea where the fishery was focused.

Mexico:  Fishing was banned in Mexico in 2007, when the Mexican Government issued “NOM-029 - PESCA RESPONSABLE DE TIBURONES Y RAYAS. ESPECIFICACIONES PARA SU APROVECHAMIENTO” (The Mexican Official Standard Rules that Regulate the Shark and Ray Fisheries in Mexican Waters). This made it illegal to capture or kill Giant Manta Rays in Mexican waters. NOM 029 provides specific protection for mantas and mobulids in all Mexican waters and prohibits their possession and trade (Norma Oficial Mexicana Nom-029-Pesc-2006, pesca responsable de tiburones y rayas. Especificaciones para su aprovechamiento, 2005). Mantas are protected in MPAs within Mexican waters, primarily in the Revillagigedo biosphere, following enforcement of a fishing closure, which began in early 2002. Enforcement for this protection has been somewhat suspect as many fishing boats have been observed and caught deploying longlines, gillnets and seines within the biosphere, which extends as a 12 mile buffer around each of the islands in the archipelago. Meanwhile, since 2004, in the Yum Balam protected area (Isla Holbox, Mexico) manta rays have been protected under strict no fishing laws. The Giant Manta Ray is only used here for tourism purposes, although this new activity could also be affecting the population, with many individuals exhibiting boat injuries.

Brazil:  There is no legal action concerning manta ray captures in Brazil. The local population is benefited by the fact that their best-known aggregation site happens to be inside an established MPA. However, it is a tiny fraction of the range of this species, as they migrate during most of the year and other unprotected aggregation sites are likely to exist. The rise of a local NGO (Instituto Laje Viva), dedicated to protect them, had eventually culminated in the first efforts to gather formal scientific data from Brazilian manta rays. The manta ray is a highly promoted flagship species for dive tourism in the region and best practices for responsible tourism have been largely advocated.

Ecuador:  On 26 August 2010, the Subsecretaria de Recursos Pesqueros declared “Acuerdo 093”, a new law prohibiting all fishing of Manta and Mobula in Ecuador, that states 1). directed fishing for the Giant Manta Ray, and several mobulid species is now illegal via any form of fishing method whatsoever; 2). in the event of incidental capture any individuals must be returned immediately to their natural environment; 3). the species mentioned cannot be retained alive or dead, whole or in part, nor can they be kept for human consumption or owned, sold or transported. The law came in response to pressure to close a newly created directed fishery for Mobula that had arisen in a very short period via Peruvian buyers who were ordering the product for export.

Western Australia:  Manta rays whilst not targeted, are protected from any fishing (Fisheries Act) and disturbance or harassment (DEC Act) within marine parks only.

New Zealand:  Absolutely protected under the Wildlife Act 1953.

Amended [top]

Amended reason: This amended version of the 2010 assessment was created to update the scientific name: previously on the Red List as Manta birostris, this species has now been moved to Mobula.

Citation: Marshall, A., Bennett, M.B., Kodja, G., Hinojosa-Alvarez, S., Galvan-Magana, F., Harding, M., Stevens, G. & Kashiwagi, T. 2018. Mobula birostris (amended version of 2011 assessment). The IUCN Red List of Threatened Species 2018: e.T198921A126669349. . Downloaded on 23 September 2018.
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