Shorttail Fanskate: Sympterygia brevicaudata

Family: Arhynchobatidae

Common name(s)

Shorttail Fanskate

Identification

A medium-sized softnose skate with a broad heart-shaped disc; disc width ~1.2 times disc length. Eyes small. Orbit length 0.34-0.41 x snout length. Mouth relatively wide. Nasal flaps broadly lobed. Snout short, broad, and rounded with a small protruding tip. Pectoral fin anterior margins undulate; convex with a central concavity. Pectoral apices narrowly rounded. Pelvic fins large and long with weakly notched, broadly rounded outer margins. Anterior pectoral radials extend almost to snout tip.
Single pre and post-orbital thorns. Midline thorns discontinuous or ranging in size; more prominent on nape and tail. Dense thorn patches also present posteriorly on pectoral fins (personal observation). Tail short, firm, and narrow-based. Two well-developed, narrowly separated dorsal fins near tip of tail. Claspers slender with pointed tips.

Colour

Dorsum pale grey or pale greyish brown with numerous small black spots and blotches. Large dark ocelli on each pectoral fin. Blotches form a radial pattern around pectoral margins. Dark bands and small spots on tail. Ventrum mostly white.
Dorsal markings are described as ‘often indistinct’ but this may be due to the faded condition of dead or moribund specimens.

Size

Maximum length ~55cm. Length at birth unknown.

Habitat

Temperate seas. Demersal on soft bottoms and rocky reefs. From close inshore to at least 100m. Shorttail fanskates are very likely found much deeper as they are a bicatch in the hake and deepwater crustacean fishery that operates at ~500m.

Distribution

Southeastern Pacific. Occurs from Ecuador to Central Chile.

Conservation Status

NEAR THREATENED

The shorttail fanskate is more commonly reported and taken as bycatch of artisanal and industrial shrimp fisheries in Ecuador and Peru, but it is rarely captured in Chile. In Ecuador, it is taken as bycatch in the multi-purpose research fishery, which captures Brown and Pink Shrimp (Farefantepenaeus californiensis and F. brevirostris) and these shrimps have a depth range of 10–110 m (A. Cevallos pers. comm. 2020; Acuerdo Nro. MAGAP-DSG-2015-0192-A, Ministerio de Agricultura y Ganadería). Off the central coast of Peru, there are intensive artisanal inshore fisheries with shore-based longlines and gillnets (Alfaro-Shigueto et al. 2010). There has been a ten-fold increase in the landings category called ‘Psammobatis brevicaudatus’ (which represents catches of S. brevicaudata) from approximately 600 kg in 2001 to 8,000 kg in 2010 mainly from the central north of Peru, reported at the ports of Pimentel, Huacho, Pucusana, and Eten (Instituto del Mar Del Peru, IMARPE; X. Velez-Zuazo, pers. comm., 2019). In Chile, this species is probably taken as bycatch in embayments by inshore bottom trawls and gillnet fisheries, and is frequently captured in the deep-water bottom-trawl fishery for South South Hake (Merluccius gayi); it is occasionally captured in the deep-water crustacean fisheries (Acuña et al. 1989, 2005).

Citation

Dulvy, N.K., Acuña, E., Bustamante, C., Cevallos, A., Concha, F., Herman, K. & Velez-Zuazo, X. 2020. Sympterygia brevicaudata. The IUCN Red List of Threatened Species 2020: e.T44596A124434224. https://dx.doi.org/10.2305/IUCN.UK.2020-3.RLTS.T44596A124434224.en. Downloaded on 05 April 2021.

Reproduction

Oviparous. Casing length 4-5cm, with short curved anterior horns and filamentous posterior horns that are sub-equal to casing length.

Diet

Mostly polychaete worms and small benthic crustaceans

Behavior

Poorly known.

Reaction to divers

Easily approached. Even when sand is wafted off of its disc, the shorttail fanskate generally remains motionless.

Diving logistics

Likely also common in Peru and Ecuador, but I have only encountered this species in central Chile. At Las Tacas in early November, I stumbled upon two animals in approximately 10m depth. They are apparently common in this area. It is possible they change depth seasonally.