Common name(s)
Rasptail Skate, Velez Skate.
Identification
A medium-sized skate with a wide kite-shaped disc. Disc width ~1.3 x disc length. Snout moderately long, obtusely angular or broadly rounded, with a thin, protruding tip. Snout length ~2.4 x orbit length. Eyes large. Anterior margins of pectoral fins weakly undulate. Pectoral apices angular or narrowly rounded. Disc sparsely covered in granulations in juveniles, mostly on snout and tail, more widespread in adults. Smooth ventrally. Thorns present around orbits, on shoulders, and along midline to first dorsal fin. Midline thorns larger near nape and on tail. Lateral thorns also present on tail. Pelvic fins large, strongly notched. Anterior pelvic lobe well defined but much shorter than posterior lobe. Tail broad, depressed, shorter than pre-cloacal disc length. weak lateral skin folds on tail. Dorsal fins rounded, slightly separated. Caudal fin very small.
Colour
Dorsum brownish with a single pair of well defined pectoral ocelli consisting of concentric light and dark circles; central spot may be pale or dark. Tail unmarked. Ventrum mostly white, dusky at pectoral apices and along posterior margin.
Size
Maximum length ~83cm. Length at hatching unknown.
Habitat
Warm temperate to tropical seas. Demersal mostly on sand and mud. From 30-300m.
Distribution
Eastern Pacific. The rasptail skate occurs from the northern Sea of Cortez to northern Peru, including the Galápagos Islands.
Conservation Status
VULNERABLE
The Rasptail Skate (Rostroraja velezi) is captured in commercial demersal trawl and in artisanal gillnet and longline fisheries, which are intense and largely unmanaged across much of its range. Trawl fisheries are intense in parts of the Gulf of California, and gillnets have been responsible for depletion of various marine species. Further south in Mexico, longline and trawl fisheries have been in operation since at least the 1960s with little management in place. Artisanal fisheries are intense and unmanaged throughout the Central and South American portions of its range, and there are unmanaged trawl fisheries in many areas. It may have some refuge on the upper slope in some parts of its range, and in the Galápagos Islands. Overall, due to the level of intense and largely unmanaged fishing pressure across much of its range and its known susceptibility to capture in these fisheries, it is suspected that the Rasptail Skate has undergone a population reduction of 30–49% over the past three generations (30 years), and it is assessed as Vulnerable A2d.
Citation
Pollom, R., Avalos, C., Bizzarro, J., Burgos-Vázquez, M.I., Cevallos, A., Espinoza, M., González, A., Herman, K., Mejía-Falla, P.A., Morales-Saldaña, J.M., Navia, A.F., Pérez Jiménez, J.C., Sosa-Nishizaki, O. & Velez-Zuazo, X. 2020. Rostroraja velezi. The IUCN Red List of Threatened Species 2020: e.T161344A124469210. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T161344A124469210.en. Downloaded on 27 April 2021.
Reproduction
Oviparous. Life history poorly known.
Diet
Rasptail skates mainly feed on decapod crustaceans and small bony fishes.
Behavior
Migratory patterns poorly known. Found in 30m in La Paz Bay in April.
Reaction to divers
Poorly known.
Diving logistics
The rasptail skate is rarely if ever encountered by scuba divers. I encountered this species while accompanying researchers in La Paz Bay in April. It was tagged and released in ~30m so a deep search on sand or mixed bottoms at this depth may facilitate encounters.
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Similar species
California Skate Beringraja inornata Distinguishable by covering faint pale spots and much smaller, simpler ocelli.
Cortez Skate Beringraja cortezensis Distinguishable by covering of dark black spots and simpler ocelli.