Pelagic Stingray, Pteroplatytrygon violacea
Pelagic Stingray, Pteroplatytrygon violacea. Fish caught in coastal waters off Puerto Adolfo Lopez Mateos, Baja California Sur, May 2017. Total length: 42 cm (16 inches). Catch and photograph courtesy of by Jimmy Camacho, Puerto Adolfo Lopez Mateos, Baja California Sur.
Pelagic Stingray, Pteroplatytrygon violacea. Fish caught from coastal waters off Point Palmilla, Baja California Sur, September 2005. Total length: 44 cm (17 inches).
Pelagic Stingray, Pteroplatytrygon violacea. Fish caught by the commercial fishermen of the greater Los Cabos area, Baja California Sur, September 2014. Note: the tail has two spines. The second spine is generated on an annual basis due to anticipated loss of the first spine in hand-to-hand gorilla combat along the road of life. Disc width: ca. 1.6 meters (5 feet 3 inches).
Pelagic Stingray, Pteroplatytrygon violacea. Underwater photograph taken in Zihuantanejo Bay, Guerrero, March 2018. Photographs courtesy of Ron Woheau, Zihuantanejo.
The Pelagic Stingray, Pteroplatytrygon violacea, is a member of the Whiptail Stringray or Dasyatidae Family, and is known in Mexico as raya látigo obispo. It is the sole global species in the genus Pteroplatytrygon and is found in Mexican waters of the Atlantic Ocean and the Pacific Ocean.
The Pelagic Stingray has a very thick wedge-shaped discs with broadly curved margins and are one-third wider than they are long. They are uniformly dark brown dorsally without distinguishing markings and off-white ventrally. Their head has a short rounded snout with a rounded tip, a small mouth equipped with long sharp pointed teeth, and minute and non-protruding eyes with a pair of spiracles following immediately behind. Their disc is elevated in the middle third; it has a front margin that is broadly convex and straight sides. Their pectoral fins are flattened and continuous and extend from their head to their tail base. The margins of their pelvic fins are straight in front and rounded at the tips in the back. They have a whip-like tail with a thick base that is twice the length of their disc; their tail has no upper finfold, a long lower finfold ending far in front of the tip, and a strongly serrated spine placed approximately one third along its length. Juveniles have smooth skin; with age they develop small prickles over the center of their back and a row of small thorns along the midline from their eyes to their spine.
The Pelagic Stringray has a global distribution and are found in all open oceanic waters and inshore bays in waters warmer than 19oC (66oF). They are found almost exclusively in the open ocean from the surface to depths of 330 feet over deeper waters. They are a relatively small ray that can reach 2.6 meters (8 feet 5 inches) in total length with a disc width of 1.6 meters (5 feet 2 inches); and up to 46.4 kg (102 lbs) in weight. They are known to make seasonal migrations following warm water masses and are found on the continental shelf and at higher latitudes during summer months. They are a mid-water species and swim by flapping their pectoral fins, with is atypical for stingrays, which are commonly bottom dwellers. They have a keen sense of electroreception and are capable of detecting minute electric fields produced by potential prey from long distances. They are active predators and known to hunt in packs at times. They consume a wide variety of pelagic organisms including amphipods, crabs, krill, octopus, squid, and bony fish. They are preyed upon by sharks (Oceanic Whitetip and Great White), large tuna, and Toothed Whales. They utilize their color for camouflage and their venomous tail spine for protection. Reproduction occurs via aplacental viviparity with internal fertilization. Embryos are sustained by a yolk sac after which they are nourished by uterine milk secreted by their mother. After a gestation period of two to four months 4 to 13 miniature adults are born that have disc widths of 15.0 cm (5.9 inches) to 25 cm (10 inches) across. Their lifespan is between ten and twelve years. Note: I caught a Pelagic Stringray 10 miles north of Puerto Los Cabos, Baja California Sur in September 2005 (disc: 53 cm x 42 cm; tail: 81 cm with a 10 cm stinger). It was a female that gave birth to five babies measuring 18 cm x 13 cm with a tail length of 43 cm in the fish box which were released to the ocean.
The Pelagic Stingrays are found in all Mexican waters of the Atlantic and the Pacific Ocean.
The Pelagic Stringray is straightforward to identify due to its elevated stealth bomber appearance and the lack of protruding eyes found in other stingrays.
From a conservation perspective the Pelagic Stringray is currently considered to be of Least Concern with stable, widely distributed areas. In some areas an increase in their populations have occurred which is attributed to declines in global populations of their predators and competitors, large sharks. The Pelagic Stingrays are not fished commercially but often caught and discarded with high mortality rates as a by-catch of pelagic long lingers and in drift nets for tuna and swordfish. Other than commercial fishermen they are seldom seen by human. They thrive in well-maintained public aquariums on a limited basis. When captured and handled they exude a thick black mucus that covers their body. They should be considered extremely dangerous and have been known to kill humans with their tail spine most notably, Steve Irwin, The Croc Hunter of television fame.