Panamic Stingray, Urotrygon aspidura
Panamic Stingray, Urotrygon aspidura. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, May 2011. Total length: 52 cm (20 inches). Disc: 28 cm (11 inches) x 25 cm (10 inches). Tail: 24 cm (9.4 inches).
The Panamic Stingray, Urotrygon aspidura, is a member of the American Round Stingray or Urotrygonidae Family, and is known in Mexico as raya redonda panámica. Globally, there are thirteen species in the genus Urotrygon, of which five are found in Mexican waters, all in the Pacific Ocean.
The Panamic Stingray has a flat oval body that have a greater depth than length. Their discs have fairly straight front margins. They vary in color from grayish brown in the center to reddish brown at the disc edge. Their ventral side is off white with a pinkish tinge. Their heads have small eyes and a pointed snout with their eyes and spiracles being on top of their heads and their mouths, nostrils, and gill slits are on the ventral side. Their pelvic fins have straight rear edges and their tails are slightly longer than the disc length and have a narrow rounded caudal fin. They feature a row of six large thorns (a key to identification) running from the base to the middle of the tail which is followed by a large venomous spine. Their discs are sparsely covered with small denticles.
The Panamic Stingray is a demersal species that is found over and within sandy and muddy bottoms, but are occasionally found in rocky reef areas at depths up to 100 m (330 feet). They are most abundant at depths less than 15 m (50 feet) and move to greater depths during cold-water episodes.
The Panamic Stingray can reach a maximum length of 50 cm (20 inches) with discs having a maximum width of 23 cm (9.1 inches). They seek food by stirring the bottom sediment with their pectoral fins to dislodge small crustaceans, small fish, mussels, and worms on which they feed. Reproduction occurs via internal fertilization with embryos developing via aplacental vivparity with a gestation period of 3 months. Their pups are born alive and resemble miniature adults that are independent at birth. The Panamic Stingray is a 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 Panamic Stingray is a resident of Mexican waters of the Pacific but has a limited distribution being found from Guerrero Negro, Baja California, southward along the central and southwest coasts of Baja and along the coast of the mainland south to Guatemala. At present they have not been documented as residents of the Sea of Cortez.
The Panamic Stingray cannot be confused with any other species due to the row of six large thorns running from the base to the middle of the tail.
From a conservation perspective the Panamic Stingray is currently classified as Data Deficient. They are a rare species and seldom seen by humans. From a fishing perspective, they are only retained by subsistence fishermen and generally considered to be a “catch and release.”