Shovelnose Guitarfish: Pseudobatos productus

Family: Rhinobatidae

Common name(s)

Shovelnose Guitarfish.

Identification

A very large guitarfish with a moderately long, wedge-shaped snout with an acutely pointed or narrowly rounded tip. Rostral ridges separated long most of their length but connected anteriorly, and sub-parallel; diverging slightly posteriorly. Eyes large. Snout length ~4.3 x orbit length. Spiracles with 2 skin folds on posterior margin; outer fold larger than inner. Nostrils large, positioned obliquely. Nasal curtain absent. Anterior nasal flaps extend over nostril opening but not beyond.
Anterior margins of disc straight. Pectoral apices broadly rounded. Skin completely covered in small denticles. Small thorns on rostral ridge, around orbits and above spiracles, on shoulders, and along midline and tail.
Tail robust and long; 1.3-1.4 x disc length. Dorsal fins large and well separated, with acutely rounded apices. Caudal fin triangular, without a defined lower caudal lobe, upper tip acute.

Colour

Dorsum greyish-brown to yellow-brown, usually with diffuse, darker blotches. Rostral cartilage matches dorsal coloration and is relatively indistinct. Ventrum white. Tip of snout sometimes dusky.

Size

Maximum length 170cm. Size at birth 20-24cm.

Habitat

Tropical/temperate seas. Benthic in shallow coastal environments such as estuaries, sea grass beds, sandy bays, and in kelp forests. Intertidal to 90m.

Distribution

Eastern Pacific. The shovelnose guitarfish occurs from San Francisco Bay, California, southward to at least the southern Gulf of California, and possibly to southern Mexico.

Conservation Status

NEAR THREATENED

In Mexican waters, the shovelnose guitarfish is taken in directed artisanal elasmobranch fisheries in both the Gulf of California and on the Pacific coast of Baja California, and is also retained as bycatch by demersal trawls and gillnets. This guitarfish is the most heavily targeted batoid in north Pacific Mexico. Catches of the Bahía Almejas fishery in Baja California Sur declined severely following a large increase in effort during the mid- to late 1990s. In Californian waters, recreational fishing derby data from Elkhorn Slough, central California suggest that this species has declined by 74% over three generations. Landings in California have also declined, although these declines do not necessarily correspond to population declines. In 2012, an annual seasonal closure on elasmobranch fishing was implemented from May 1 to July 31 along the Mexican Pacific coast, and other recent monitoring and management changes have been made in Mexico. Nonetheless, given ongoing target and bycatch fisheries for this species in Mexico, an absence of species-specific data in Mexican logbooks, and recreational fishing derbies in the United States, the Shovelnose Guitarfish is is assessed as Near Threatened, as we suspect that this species has declined by nearly 30% over the past three generations.

Citation

Farrugia, T.J., Márquez-Farías, F., Freedman, R.M., Lowe, C.G, Smith, W.D. & Bizzarro, J.J. 2016. Pseudobatos productus. The IUCN Red List of Threatened Species 2016: e.T60171A104004394. https://dx.doi.org/10.2305/IUCN.UK.2016-3.RLTS.T60171A104004394.en. Downloaded on 27 May 2021.

Reproduction

Aplacental viviparous. Litter size up to 1-16 pups.

Diet

Feeds on crabs, worms, clams, and bony fishes.

Behavior

Shovelnose guitarfish form large aggregations in the surf zone off Southern California during the summer months.

Reaction to divers

Skittish. Difficult to approach when encountered on snorkel in the surf zone. More approachable when resting in the kelp forest.

Diving logistics

The shovelnose guitarfish is one of the most commonly encountered rays in the summer in southern California. A good place to look for them is directly off the beach near the Marine Room Restaurant in La Jolla. At this spot, waves of shovelnose rays and leopard sharks migrate inshore during the summer. They can be encountered in just a meter or two of water.