Featured Elasmobranch–Diamond Stingray
Category : Featured Elasmobranch
Dasyatis dipterura (Jordan and Gilbert 1880)
Family Dasyatidae (Whiptail Stingrays)
Identification: The disc is diamond shaped, and slightly wider than it is long. The snout is pointed and the teeth are small and molar-like. This species has a long whiplike tail that is less than 1.5 times the disc length, with a long slender stinging spine. Dorsal surface coloration is brownish to gray or black with reddish areas near the disc edges; ventral surface is white.
Size: Maximum disc width (DW) is at least 88 cm, but possibly up to 120 cm for females, and with males reaching a maximum DW of 86 cm.
Distribution: Southern California to northern Chile and the Galapagos Islands. They are rare in southern California but increase in abundance off Baja California and in the Gulf of California. These stringrays are more abundant in California waters during El Niño events where exceptionally warm water masses are in the area.
Habitat: This is a warm-temperate to tropical species, found inshore and down to 17 m. They are found over muddy or sandy bottoms near rocky reefs and kelp forests, and are concentrated more around kelp beds in the winter. In the fall and winter, they aggregate at depths of 12 to 17m, and at other times of the year are found in shallower water of two to seven meters.
Biology: Reproductive mode is yolk-sac placenta viviparity, with a gestation period of two to three months. The litter size is from one to four pups. This species exhibits strong sexual segregation by size and sex. Nursery grounds are located off the Pacific coast of Baja California, and birth occurs in late summer from August to September. El Niño may result in pupping earlier in the summer. This species is thought to live about 28 years, with females maturing at a disc width of 65 cm. The growth rate of females is thought to be the slowest of any dasyatid. Males mature at 50 to 65 cm disc width. Size at birth is from 19 to 23 cm disc width. Diamond stingrays feed on benthic crustaceans such as crabs, shrimps, and small fishes. They are known to forage by swimming along the bottom searching until they find food. Once a prey item is located, the stingray uses the pectoral fins to create a rapid, continuous up and down motion to create a vacuum, which draws the prey out of the benthos. The stingrays are most active at night when foraging for food, singly or in groups of up to hundreds.
General interest: The IUCN lists this species as Data Deficient. Although not in enough numbers to be of commercial importance in California, this species comprises 10 percent of the elasmobranchs caught seasonally (both commercially and as bycatch) in Mexican waters. Most of the fishing effort is centered in spring and summer when the females give birth although they are taken throughout the year. It is also taken commercially in Central and South American waters. The wings are used for human consumption and are sold fresh, filleted, or salted. The spine has caused at least one human death but the rays usually flee when approached by divers. Two different descriptions of this species with different scientific names were published in the same year but Jordan and Gilbert’s is recognized as it was published first.
By Jennifer Bigman
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039