Featured Elasmobranch- Whitenose Guitarfish
Category : Featured Elasmobranch
Rhinobatus leucorhynchus (Günther 1866)
Family Rhinobatidae (Guitarfishes)
Identification: Disc rather long, snout tip acute, rostral ridges separated for entire length, converging near snout tip. Eyes moderate-sized, with interorbital width about 3.5 times into snout length; spiracles smaller than eyes. Small spines present on orbital ridges and around spiracles, and on midback extending to second dorsal fin, and a pair of spines on each shoulder. Coloration is a dark grey dorsal surface, except for the snout, which is distinctly lighter to white (hence the common name ‘whitenose’ guitarfish), and a lighter ventral surface; dorsal surface occasionally with scattered pale spots.
Size: A relatively small guitarfish, with maximum size of 62.5 cm total length. The size at birth is unknown.
Distribution: This species is distributed in the eastern central and southwest Pacific Ocean from central Baja California, Mexico, including the Gulf of California to Ecuador. There have been unverified reports of this species occurring as far south as Peru and around the Galapagos Islands. It is rare in the northern Gulf of California and Baja, but common south of Mazatlan, Mexico.
Habitat: A demersal, benthic guitarfish common in marine and coastal embayments, usually found over sandy substrates. This species ranges from the intertidal to about 8 m, but may range down to 50 m deep.
Biology: A common, but little known guitarfish. This species has a yearly reproductive cycle, with litters of 2 to 16, but nothing is known regarding its age or size at maturity. There is nothing known about its diet, but it likely feeds on benthic invertebrates including crustaceans, mollusks, and possibly small benthic fishes.
General interest: The IUCN lists this species as Near Threatened due to a directed elasmobranch fishery in Mexican waters. In the Gulf of California they are taken in local artisanal elasmobranch fisheries and are commonly taken in larger commercial trawl and gillnet fisheries. In addition to fishing this species is vulnerable to habitat modification given their inshore habitat preference.
By Jennifer Bigman
Pacific Shark Research Center
Moss Landing Marine Laboratories
8272 Moss Landing Road, Moss Landing, CA 95039