Species Details

Details of Spotted eagle ray will be displayed below

Spotted eagle ray   

Common Name: Spotted eagle ray
Scientific Name: Aetobatus narinari
Local Name: vaifiya madi
Dhivehi Name: ވައިފިޔަ މަޑި
Animalia  (Kingdom)
Chordata  (Plylum)
Rajiformes  (Order)
Myliobatidae  (Family)
Aetobatus   (Genus)

Spotted eagle ray's description

White-spotted eagle ray, grow to at least 3.5m disc width and 9m total length. The spotted eagle ray has a long snout, flat and rounded like a duck\\\'s bill, a thick head, and a pectoral disc with sharply curved, angular corners, and no caudal fin; jaws usually with single row of flat, chevron-shaped teeth. Each tooth is a crescent-shaped plate joined into a band. They usually have numerous white spots on black or bluish disc; with white below. Long whip-like tail, with a long spine near the base, behind small dorsal fin.

Spotted eagle ray habitat

Coastal and semipelagic over the continental shelf from the surface to 60 m depth. Sometimes enters lagoons and estuaries and often associated with coral-reef ecosystems (Michael 1993, Homma et al. 1994, Last and Stevens 1994). Solitary or found in large schools of up to several hundred individuals (McEachran and de Carvalho 2002). Although primarily observed near the coast and around islands and reefs, the species is likely to be capable of crossing ocean basins (Compagno and Last 1999).

Around coral reef environments, spotted eagle rays often enter coral lagoons to feed (Pohnpei Island, Federated States of Micronesia; Homma et al. 1994). Diet consists of a wide variety of benthic species including polychaetes, bivalve and gastropod molluscs, cephalopods, crustaceans and teleost fishes (Homma and Ishihara 1994, Last and Stevens 1994, Compagno and Last 1999, McEachran and de Carvalho 2002) with fish important prey items for adults (Michael 1993).

Aplacental viviparous. Little information available on reproductive biology although known to have low fecundity, bearing 1 to 4 pups/litter (Last and Stevens 1994). Homma et al. (1994) observed three gravid females in the Caroline Islands, two individuals carrying a single embryo and one carrying two embryos. Gestation has been reported at 12 months (Michael 1993) and reproductive periodicity may not be annual. These factors combine for limited reproductive output. Reported to reach sexual maturity after 4 to 6 years (Last and Stevens 1994). Although reaches 330 cm DW most observed are less than 200 cm DW (Compagno and Last 1999).

Catches taken in the protective shark nets off the beaches of KwaZulu-Natal, South Africa, occur throughout the year but peak in summer (January and February) (Young 2001). The overall sex ratio is unity but there is a significant association between sex and time of year, with more males than females caught in summer and more females than males in winter. Median disc width for each sex is 100 cm (Young 2001). Catches are rare in the southern part of the netted region, an apparent consequence of lower water temperatures (Young 2001).

It should be recognised that life history parameters are likely to vary between the different forms of A. narinari, which may turn out to represent interspecific differences.

Life history parameters
Age at maturity: 4 to 6 years (Last and Stevens 1994) (female); 4 to 6 years (Last and Stevens 1994) (male).
Size at maturity (total length): Unknown (female); Between 100 and 115 cm DW (Indonesia; W. White unpubl. data) (male).
Longevity (years): Unknown.
Maximum size (total length): 330 cm DW (Last and Stevens 1994).
Size at birth: 26 cm DW (Last and Stevens 1994), 17 to 36 cm DW (Compagno and Last 1999).
Average reproductive age (years): Unknown.
Gestation time: 12 months (Michael 1993), but may be less..
Reproductive periodicity: Unknown.
Average annual fecundity or litter size: 1 to 4 pups/litter (Last and Stevens 1994).
Annual rate of population increase: Unknown.
Natural mortality: Unknown.

Spotted eagle ray threats

Details of catches of this species throughout its range are scant. Nevertheless its small litter size, schooling behaviour, inshore habitat and hence availability to a wide variety of inshore fishing gear (beach seine, gillnet, purse seine, benthic longline, trawl etc.), its marketability and the generally intense and unregulated nature of inshore fisheries across large parts of the species' range warrant a global listing of Near Threatened, and a Vulnerable listing in Southeast Asia where fishing pressure is particularly intense and the species is a common component of landings. With further data it will likely fall into a threatened category in other regions also.

This species occurs in coastal inshore waters where fishing pressure is typically very heavy, especially in SE Asian waters, in parts of Africa and through portions of the species' range in the Americas. The strong swimming nature of this species makes it quite susceptible to a range of fisheries, especially inshore gill net fisheries, which are extremely intensive in some regions (for example, Kalimantan in Indonesia). The species also enters estuarine waters where fishing pressure is also extremely high and where (in SE Asia at least) pollution is also a major factor for all marine life.

The species is likely to contribute substantially to numerous inshore artisanal fisheries across its range and it is known to be landed regularly in some places. In Southeast Asia, Aetobatus narinari is landed in most countries within its range, for example, Indonesia (W. White unpublished data), Thailand (Vidthayanon 2002), the Philippines (Compagno et al. 2005), Taiwan (W. White and P. Kyne pers. obs.) and Malaysia (Manjaji 2002), all of which are countries where fishing pressure on the inshore environment is intense and generally unregulated. In Indonesia the species is presently caught consistently but in only small numbers in many fisheries (W. White unpublished data) and expected future declines in SE Asia are the basis for the Vulnerable listing there. The species is probably widely utilized across its range (Compagno and Last 1999) due to its availability to fisheries. Fishing pressure on the inshore environment across most of the species' range is only likely to increase in the future.

Off eastern Africa, it is commonly caught by artisanal fishermen, in bottom set gillnets, trawls and longlines in Tanzania (Bianchi 1985), by artisanal gillnet fisheries off northern Madagascar (Doukakis and Jonahson 2003, Robinson in prep.) and by hook and line and harpoon off Somalia (Sommer et al. 1996).

Although specific details are not available, pressure on the inshore environment through artisanal fishing activities off West Africa, throughout the Arabian Sea, the Bay of Bengal and in large portions of the species' American range has likely affecting this species. There is nothing to suggest that pressure will decrease in these regions in the future.

In South Africa, between 1981 and 2000 there was a non-significant increasing trend in catch of A. narinari in the protective shark nets off KwaZulu-Natal (Young 2001). Of the mean annual catch of 16 animals, 82% were released alive. The species contributed 4.6% to the total batoid catch. Aetobatus narinari is taken in small numbers as bycatch in a shallow water prawn trawl fishery that operates off central KwaZulu-Natal (Fennessy 1994).

It is a popular public aquarium species and is collected for the marine aquarium trade. In some localities it is likely to be persecuted when considered a pest of mollusc aquaculture farms, as has occurred with other myliobatid species, for example Myliobatis californicus (Gray et al. 1997).

In a few parts of its range the species faces lower levels of threat. These include South Africa where catch levels are low, the USA where the species is protected in Florida (see Conservation Measures below), the Maldives where the exportation of ray product is banned, parts of Oceania where human populations are low, and Australia. The species is afforded some protection and impact reduction in parts of Australia in Marine Protected Areas, by the use of Turtle Exclusion Devices in prawn trawl fisheries and because of spiritual significance in some indigenous communities (see Conservation Measures). However, there is still concern for the species in Australia where it is taken as bycatch in inshore net fisheries and marketed as ?skate wings?, ?ray flaps? or ?eagle ray flaps?. Eagle ray is becoming an increasingly popular seafood product in Australia and the landing of this product is likely to increase in the future.

Spotted eagle ray's status