Big Skate - Raja binoculata

 Big Skate - raja binoculata

View all Big Skate Images in the Pacific Marine Index

Big Skates (Raja binoculata) are found in temperate waters of the Eastern Pacific Ocean. Their range includes the Eastern Bering Sea and Aleutian Islands, West to Unalaska Island and South to Baja, California (U.S.) near Cedros Island. These skates can be found in waters from the intertidal range to depths of 394 feet (120 m.) inhabiting the coast in estuaries, bays, and over the continental shelf. Although this skate is sometimes observed in low stands of kelp, it is more common to find them on sandy and muddy bottoms where they can be seen hiding motionless in the bottom sediments with only eyes protruding, camouflaged from potential predators. When this skate does move, swimming occurs by the undulation of the pectoral fins, which makes the skate appear as though it is "flying" gracefully through the water.

The Big Skate was originally described by Girard, in 1855 as Raja binoculata. The genus name Raja is derived from the Latin "raja" meaning skate, and the species name binoculata means two eyes, referring to the spots on the pectoral fins. Big Skates are the largest members of the Rajidae family, growing up to 2.5 m. (8 ft.) long, and weighing up to 90 kg. (200 lbs.) They have a flattened diamond-shaped body with a stiff snout tapering to a blunt point. Their small eyes are positioned on the dorsal surface some distance from the pointed snout with large spiracles just posterior to the eyes. The mouth is on the ventral surface along with the five gill slits. The pectoral fins are not clearly distinct, attaching the snout with the body, and these fins have a concave anterior edge between the snout and pointed tips of the fins. The two small dorsal fins are located on the tail while the anal and caudal fins are absent. The pelvic fins on this skate are large, moderately concave, and weakly notched along the free margins and the tail is long and narrow with a fleshy keel on either side.

The Big Skate is an oviparous, or egg-laying, species. It has probably the largest egg capsules in the Rajidae family, with each measuring 9-12 inches (22.8-30.5 cm) long and 4-7 inches (11.0-19.4 cm) wide. The egg capsules are oblong in shape with horns at each corner and are the only known egg capsules to contain more than one egg inside along with the eggs of the Mottled Skate (R. pulchra). These egg capsules commonly contain 3-4 eggs; although up to 7 have been documented. The female releases the egg capsules in pairs on sandy or muddy substrate which hatch about nine months after being released from the female. The empty black egg cases referred to as mermaid's purses, sometimes wash ashore and are found by beach combers.

Skates mature at a late age, have slow growth rates, and low reproductive rates, making skates potentially vulnerable to overfishing. The Big Skate is of only minor importance to commercial fisheries. However, it is often taken incidentally as bycatch primarily by bottom trawlers in the waters off the coast of California (U.S.). The pectoral fins are sometimes marketed as "skate wings" and as scallops (punched from the pectoral fins), although the flesh of skates is not highly regarded for human consumption. Anglers occasionally take this species, however they are usually released or discarded. All these factors make skates potentially vulnerable to overfishing, and as such, warrant close monitoring of populations.

Photographing skates and rays, or any other flat fish has its challenges as most of these creatures reside motionless on a flat substrate, usually sand. Sand can be a frustrating element in underwater photography. It is usually brighter and more reflective than the subject so it overexposes easily, and it is also easily stirred up by surge or divers and can be very slow to resettle. Photographing any subject in this medium presents a bland background to the viewer that renders the majority of skate and ray images unappealing except for their identification value. The best way to combat these issues is to get as low as you can to your subject and shoot horizontally. Try to incorporate bits of kelp or rocks into the shot, as breaking up the background will make all the difference to the mood of the image. 

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