Lesser Electric Ray, Narcine bancroftii

Note:  This Species is currently considered to be ENDANGERED and if encountered should be handled accordingly.

Lesser Electric Ray, Narcine banchroftii. Underwater photograph taken in coastal waters of Yal-Ku, Quintana Roo, April 2016. Photograph courtesy of Juan Rojo, Akumal.

The Lesser Electric Ray, Narcine bancroftii, is a member of the Electric Ray or Narcinidae Family, that is also known as the Caribbean Electric Ray and the Caribbean Numbfish and in Mexico as raya eléctrica torpedo. Globally, there are fifteen species in the genus Narcine, of which three are found in Mexican waters, one in the Atlantic and two in the Pacific Ocean.

The Lesser Electric Ray has an elongated flattened oval disc that is slightly wider than it is long that has soft flaccid edges. They vary significantly in color either being a uniform sand color or yellowish-brown to dark brown dorsally with an irregular dark crossbar on the snout just before the eyes, dark spots forming indistinct ocelli over the disc and base of the caudal fin and a caudal fin and dorsal fin with dark crossbars at the base. The ventral side is white, yellowish or light green. The juveniles have a number of blotches, dark oval loops and dark rings dorsally. Their head has a rounded snout, small gill slits, a small tubular protractile mouth, nostrils with one opening, and visible well-developed electrical organs on that originate just before the eyes and extend to the rear of the disc. Their caudal fin is short, stout and triangular in shape with a square rear margin; they have 2 equal sized large dorsal fins the first originating posterior to the end of the pelvic fins; and, the pectoral fins are enlarged to form the disk and slightly overlap the front of the pelvic fins. Their skin is soft and loose and does not have denticles or thorns.

The Lesser Electric Ray is a demersal species found in coastal shallow environments buried within mud and sand substrate at depths up to 55 m (180 feet). They reach a maximum of 60 cm (2 feet 0 inches) in length. They hide in mud, sand or seagrass during the day and emerge at night seeking food and stir the bottom sediment with their pectoral fins and dislodging small crustaceans, mollusks, polychaetes, and teleosts on which they feed. They are capable of delivering strong jolts of 14 to 37 volts that they utilize to stun prey and as a defense mechanism to ward off predation. None-the-less they are preyed upon by large fishes and sharks. Reproduction is via internal fertilization. Embryos develop by aplacental viviparity with a gestation period of 3 to 6 months and pups are born live. The fecundity rates are relatively high with litter sizes ranging from 4 to 14 but sexual maturity is not reached by females for six years. Pups are born as miniature adults and are independent from birth. The newborns are approximately 9.0 cm (3.5 inches) in length. The Lesser Electric Ray rare and is poorly studied with very limited information available about their lifestyle and behavioral patterns including specific details on age, growth, longevity, movement patterns, diet, habitat use, and reproduction.

The Letter Electric Ray is a resident of all Mexican waters of the Atlantic Ocean including the Gulf of Mexico and the east coast of the Yucatán Peninsula in the Caribbean.

The Lesser Electric Ray is a straightforward identification and cannot be confused with any other species as it is the only Electric Ray found in Mexican waters of the Atlantic Ocean.

From a conservation perspective the Lesser Electric Ray is currently considered to be CRITICALLY ENDANGERED with declining populations. Conservation efforts are severely hampered by poor landing rate data and the fact that this species remains essentially unregulated. They are a small slow-moving fish that are caught as a by-catch by shrimp fishermen and seine netters. They are not a commercially important species for human food consumption and have only a very small market within the aquarium trade. They have a low resilience having a long reproduction cycle They are deemed to be Harmless to Humans unless provoked but if accidently stepped upon the experience can be “shocking”. In some regions they are frequently encountered by scuba divers. They are scientifically interesting due to their abilities to send signals across a chemical synapse via neurotransmitters.