Featured Elasmobranch – Longtail Stingray

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Featured Elasmobranch – Longtail Stingray

Longtail Stingray

Dasyatis longa (Garman 1880)

Family: Dasyatidae

longtailstingray

Photo copyright: Andy Murch

Identification: A diamond-shaped disc, about a sixth wider than it is long; outer disc corners broadly rounded, with margins of disc being straight from snout to wingtips; snout broadly angular; mouth is curved with five oral papillae.  A central row of blunt thorns extends from the head to the shoulder girdle; two additional thorns are further back.  The pelvic fins are rounded and the tail fin is absent; fin fold present along underside of the middle of the whip-like tail, and with a long stinging spine present; behind the spine, the tail becomes laterally compressed.  Tail more than twice as long as the body, but because the length of the tail is usually damaged, it is not a reliable diagnostic character for the species.  Coloration ranges from dark brown to black with no distinct markings.  This species is often confused with the morphologically similar Diamond Stingray (D. dipterura).

Size:  Species can reach a total length of 257 cm and a disc width of at least 156 cm.  Males mature around 80 cm disc width, while females mature around 110 cm disc width.  Size at birth is approximately 40 cm disc width.

Distribution:  Species range extends from southern Baja California and the southern and southeastern Gulf of California to Ecuador, and includes the Revillagigedos, Galapagos and Malpelo Islands.

Habitat: Inhabits sandy or muddy bottoms from estuaries to continental shelves to at least 100 meters.

Biology: Information on the life history of the species is limited.  The relatively large body of this species may imply they are slow growing and have a long lifespan, but there is no confirmed evidence of this. The species mode of reproduction is viviparity, and the gestation period is presumed to be around 10 to 11 months.  Similar to other myliobatoid rays, the females possess a single functional ovary.  Litters consist of 1 to 5 pups.  In the late summer, gravid females have been captured near shallow estuaries and tidal creeks suggesting that these areas are used for pupping or nursery grounds. Feeds on benthic invertebrates and small bony fishes, but their does not appear to be any change in diet between seasons or sexes. The teeth are sexually dimorphic between adult males and females, but this appears to be related to reproductive behavior rather than diet.

General Interest: The species is caught in bottom trawls, longlines, and gill nets.  It is most vulnerable to gillnets since the tail spines of the fish increases its susceptibility of being entangled.  Because the species mainly feeds on shrimp, it is often caught as bycatch in shrimp trawl fisheries.  Although the species is commercially important at local, regional, and national levels for its meat, little is known of their population status since the fisheries are poorly monitored in Mexico and Central America.  The IUCN Red List has assessed the conservation status of the Longtail stingray as data deficient.

 

Jessica Jang

Pacific Shark Research Center

Moss Landing Marine Laboratories

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