Diamond Stingray, Hypanus dipterura
The Diamond Stingray, Hypanus dipterura, whose common Spanish name is raya látigo diamante, is a species in the Whiptail Stringray or Dasyatidae Family, known collectively as rayas látigo in Mexico. This fish has very recently been reclassified from Dipterura dipterura. Globally, there are thirty-eight species in the genus Hypanus, five of which are found in Mexican waters, three in the Atlantic and two in the Pacific.
The Diamond Stingrays have rhomboid or diamond shaped discs that are slightly wider than they are long; they have a width of up to 1.22 meters (4 feet 0 inches) and a total length of 1.80 meters (5 feet 11 inches). They are uniformly brown dorsally with darker coloration toward their tail and off-white ventrally. Their disc has flattened pectoral fins that are continuous and extend from their head to their tail base with angular outer corners and straight front margins. Their head has a blunt non-projecting snout, large eyes immediately followed by spiracles on their dorsal side, and a strong curved mouth equipped with numerous rows of small blunt teeth on their ventral side. Mature fish have a row of denticles along the midline of their back flanked by two shorter rows on their “shoulders” and a tail covered with prickles; these thorns are absent in juveniles. They have a long whip-like tail that is approximately one and a half the length of their disc with fin folds above and below. They have one venomous serrated tail spine that is closer to the base than the tip and is potentially dangerous.
The Diamond Stringrays are a demersal species found primarily in relatively shallow inshore waters over sandy and muddy bottoms or near rocky outcrops at depths up to 225 feet. They are known to migrate to deeper waters during the late fall and winter months. They are a dimorphic species with females being larger and having a longer lifespan that males. They may be found alone or in groups of varying sizes. They spend their days buried in sand half submerged on the bottom. They are active as nighttime predators and travel as solitary individuals or in groups that can number into the hundreds and are segregated by age and sex. They feed on crustaceans, molluscs, polychaetes, and other invertebrates and on small bony fish. Sexual maturity is reached after seven years in males and after ten years in females. Reproduction occurs in annual cycles via aplacental viviparity with internal fertilization. Embryos are sustained by a yolk sac for the initial sixty days after which they are nourished by uterine milk secreted by their mother. After a gestation period of two to two-and-a-half months one to four miniature adults are born that have disc widths of 18.0 cm (7.1 inches) to 23.0 cm (9.1 inches). Several bays along the Pacific coast of Baja California are known to serve as nurseries. Males have a lifespan of nineteen years and females of twenty-eight years. Although common and abundant little is known about their behavioral patterns.
In Mexican waters the Diamond Stringrays are found in all waters of the Pacific.
The Diamond Stringray is most likely and easily confused with the Longtail Stingray, Hypanus longa (tail length twice disc length; lacks upper fin folds). However, the tails in both species are often damaged making their differentiation in the field exceedingly difficult.
The Diamond Stingrays are a major focus species of artisanal elasmobranch fishery catches of the Pacific coast of Mexico and the Gulf of California and one of the most important rays to the local economies. Their catch rates are highest during the summer and fall. They are caught primarily by demersal gill nets, longlines or traps with the majority of fish being immature juveniles. They are also a significant component of the shrimp trawler by-catch. They are an important food source for local people with their pectoral fins being sold filleted and salted and are a major component of “fish tacos” sold by taco stands. They are very abundant in all waters surrounding coastal Baja California. When encountered in the wild they are not aggressive but will use their venomous tail spines if startled or stepped on inflicting very painful wounds that are not life threatening. From a conservation perspective that are considered Near Threatened in Mexico due to heavy fishing pressure, slow growth rates, long reproduction cycles with low productivity, water quality declines due to pollution, and on-going habitat destruction of coastal bays and mangrove lagoons in their nursery areas with the construction of increasing numbers of shrimp farms. They lack any form of management and catch levels lack specific details.
Diamond Stingray, Hypanus dipterura. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, July 2009. Disc size: 40 cm (16 inches) x 40 cm (16 inches). Tail length: 42 cm (17 inches). Note: the spine on the tail has been surgically removed.
Diamond Stingray, Deformed, Hypanus dipterura. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, June 2012. Disc size: 25 cm (10 inches) x 27 cm (11 inches). Tail length: 19.0 cm (7.5 inches).
Diamond Stingray, Hypanus dipterura. Fish provided by the commercial fishermen of Bahía Kino, Sonora, March 2015. Disc size: 33 cm (13 inches) x 33 cm (13 inches). Tail length: 37 cm (15 inches). Photo and identification courtesy of Maria Johnson, Prescott College Kino Bay Center, Kino Bay, Sonora.
Diamond Stingray, Hypanus dipterura. Fish caught from coastal waters within the Devil’s Curve section of Magdalena Bay, Baja California Sur, February 2017. Disc size: 51 cm (20 inches) x 43 cm (17 inches). Tail Spine: 12 cm (4.7 inches). Catch courtesy of Brad Murakami, Surrey, British Columbia, Canada. Photo courtesy of Ian Franck, New Westminster, British Columbia, Canada.
Diamond Stingray, Hypanus dipterura. Underwater photo taken in coastal waters off Buena Vista, Baja California Sur, June 2017. Disc size: 91 cm (36 inches) x 77 cm (30 inches).. Photo courtesy of Bob Hillis, Ivins, UT.