Featured Elasmobranch – Bullseye Round Stingray

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Featured Elasmobranch – Bullseye Round Stingray

Image Courtesy Christina Obrecht

Bullseye Round Stingray
Urobatis concentricus Osburn & Nichols, 1916
Family Urotrygonidae

 

Identification: Disc nearly rounded, anterior edges come together at the snout to form an obtuse angle. The distance from snout to mouth is equal to the distance from snout to eyes. At the tail end, moderately developed lateral folds extend backward towards a strong serrated spine. The caudal fin is oblong and rounded at the tip. Skin is smooth all over the body. Coloration is a light gray with dark brown markings; markings roughly form three concentric rings around a central ring in the middle of the disc, giving it s “bullseye” appearance; two narrow pale bands run along the outer edges of the disc and extend to the ventral surface. This appearance has generated several common names for U. concentricus, including Reticulated Round Ray and Spot-on-spot Round Ray.

Size: Maximum disc width up to 0.28 meters ((= ~1ft) and maximum total length is about 0.47 meters (= ~1.5ft).
Distribution: Central and lower parts of the Gulf of California, with some reports extending the range of this species down to southern Mexico.

Habitat: Commonly inhabits shallow reefs, bays, estuaries and along coastal shorelines; usually found on soft sandy or rocky bottoms.
Biology: Very little is known about the biology of this species. Breeding aggregations have been observed at Isla Santa Inés. Its diet is reported to include small fishes and crustaceans.

General Interest: There is no direct fishery, which targets U. concentricus, or other urobatid rays due to their small size. Incidental catches by shrimp trawlers are likely, however, there is no species-specific documentation on how many may be caught.

The taxonomic status of urobatid rays in the eastern Central Pacific is currently unresolved. Urobatis concentricus is morphologically very similar to two other common species, U. halleri and U. maculatus, but differs primarily in coloration; Consequently, U. concentricus, U. halleri, and U. maculatus may all represent a single species.  A detailed systematic examination of this group is sorely needed to resolve the status of these species. Given the uncertainty of the taxomonic status of this species and a lack of biological data the IUCN’s Red List of Threatened Species has assessed the species as Data Deficient

 

Victoria Vásquez

Pacific Shark Research Center

Moss Landing Marine Laboratories