Equatorial Skate, Raja equatorialis
The Equitorial Skate, Raja equatorialis, whose common Spanish name is raya ecuatorial, is a species in the Skate or Rajidae Family, known collectively as rayas in Mexico. Globally, there are thirty-two species in the genus Raja, eight of which are found in Mexican waters, three in the Atlantic and five in the Pacific.
The Equatorial Skates are shaped as large flattened rhomboid discs that include the head, body, and pectoral fins. They have a pointed head and pointed “wings”. They have a light-brown back and a white underside and the edges of the disc are pale. Their snout and spines are translucent. Their head features large spiracles behind the eyes and a rigid snout. The front edge of the disc can be straight or convex. The disc length and width are similar, whereas the tail is approximately 57% of the disc length. They have two dorsal fins at the rear of their tail and no caudal fin. Their pelvic fins have two distinct lobes with the rear lobe being the largest. The disc is covered with small, thin, oval based spines without grooves. They have one row of thorns from the nape of the neck along the back of the disc to the tail, another row on each side of the tail, a row inside and before the eyes, and four or five short rows on the edges of the disc opposite the eyes; these thorns make them truly lethal.
The Equatorial Skates are found over sandy bottoms at depths between 60 and 600 feet. They reach a maximum length of 1.0 meter (3 feet 3 inches). They consume shrimp, polychaete worms, and small benthic fish. They are oviparous and lay large eggs in black or dark green leathery shells, known as Mermaid’s Purses, which have an oblong outline with a hollow tendril at each corner used to attach to marine objects. They are produced in pairs with each case containing up to seven embryos. This species is fairly rare and has a limited distribution. Very little is known about their behavioral patterns.
In Mexican waters the Equitorial Skates have a limited distribution being found from Guerrero Negro southward along the central and southern coasts of Baja, in the southern 70% of the Sea of Cortez, and along the coast of the mainland south to Guatemala.
The Equatorial Skate can be confused with the California Skate, Raja inornata (one row of tail thorns; no thorns on edges of pectoral fins) and the Rasptail Skate, Raja velezi (large thorns on tail; two ocelli spots on back).
The Equatorial Skates are taken primarily as a by-catch of deep water shrimp trawls and by shark fishermen on hook and line. They are rare and not considered an important commercial species but are an excellent food fish and sold predominantly in fish tacos.
Equitorial Skate, Raja equatorialis, male. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, June 2009. Total Length: 52 cm (20 inches); Disc Length: 30 cm (11 inches); Disc Width 33 cm (13 inches); Tail 22 cm (8.7 inches).
Equitorial Skate, Raja equatorialis, female. Fish provided by the commercial fishermen of the greater Los Cabos area, Baja California Sur, August 2012. Total Length: 62 cm (24 inches); Disc Length: 42 cm (16 inches); Disc Width 40 cm (16 inches); Tail 20 cm (7.9 inches).