Rough Eagle Ray

Rough Eagle Ray, Pteromylaeus asperrimus

The Rough Eagle Ray, Pteromylaeus asperrimus, whose common Spanish name is águila cueruda, is a species in the Eagle Ray or Myliobatidae Family, known collectively as águilas marinas in Mexico. This fish is also known as the Striped Eagle Ray. Globally, there are only two species in the genus Pteromylaeus, one of which is found in Mexican waters, this one from of the Pacific.

The Rough Eagle Rays have flattened rhomboidal disc-shaped bodies that are approximately two times wider than they are long. They are dark reddish-brown to gray dorsally with eight to ten transverse dark lines and spots that fade quickly upon death. Their underside is off-white and their pectoral fin tips are black. Their head is large, bulbous, elevated, and protruding with a long conical snout. Their head is behind the origin of the pectoral fins; these fins are long and form equivalent triangles with pointed tips, convex front margins, and concave rear edges. Their spiracles are about twice as large as their eyes. Their mouth has flat, pavement-like plates of teeth arranged in 7 series. They have a single dorsal fin at the base of their slender and whip-like tail that is two to three times the length of the disc and contains a long venomous spine with an injecting barb at the base which is used for self-defense. They do not have a caudal fin.

The Rough Eagle Rays are an inshore species found over sandy bottoms at depths up to 165 feet. They reach a maximum disc width of 79 cm (31 inches). They consume mobile benthic gastropods and bivalves, benthic worms, sea cucumbers, sea stars and urchins, crabs, octopi, and shrimp. Reproduction occurs via ovoviviparity with internal fertilization. The embryos are initially fed on yolk then receive additional nourishment from the mother by indirect adsorption of uterine fluid enriched with mucus, fat, and protein. Pups are born live as miniature adults. Litter and pup sizes are unknown. They are uncommon in Mexican waters but more common in Pacific waters closer to the equator, however their range is poorly documented. They are poorly studied with very limited information available about their lifestyle and behavioral patterns including details on catch, age, growth, longevity, movement patterns, reproduction, and range.

In Mexican waters the Rough Eagle Rays have a limited distribution being found from Magdalena Bay southward along the southwest coast of Baja and from Mazatlán south to Guatemala along the west coast of the mainland.

The Rough Eagle Ray is most likely confused with the Longnose Eagle Ray, Myliobatis longirostris (disc width less than twice disc length; no striping on dorsal side; shorter rounded snout).

 The Rough Eagle Rays are scarce and seldom caught by artisanal fishermen. They do show up occasionally as a bycatch of demersal shrimp trawls, longlines, and gill nets and are normally discarded with a high mortality rate. There is no commercial fishery for the Rough Eagle Ray. From a conservation perspective they are currently considered “data deficient”, however, their long term viability is of concern based on their infrequent catch by artisanal fishermen, the overall population decline of many myliobatid rays, and an intense and unregulated fishery. Note: Rays of the genus Pteromylaeus have tails with a venomous spine. Although the Rough Eagle Rays are exceeding rare, they are potentially dangerous as they can inflict wounds with intense pain and slow recovery. Approximately 1,500 stings from stingrays are reported annually.

Rough Eagle Ray (1)Rough Eagle Ray (2)Rough Eagle Ray (3)

Rough Eagle Ray, Pteromylaeus asperrimus. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, July 2013. Disc width: 66 cm (26 inches); Disc length: 42 cm (16.5 inches). Note that the tail was surgically removed at the time of the catch to avoid human contact with the venomous spine.