Barn-door skate Raja laevis Mitchill 1817

Description—

The barn-door skate is easily identified by its large size, its very pointed snout, and its smooth skin. The thorns along the midline of its back are comparatively small and run only from the hinder part of the disc back along the tail; the tail also has one or two rows of large, sharp spines (smaller on males than on females) along each side, besides the median row. There are small thorns on the snout also, sometimes below as well as above, and along the front edges of the pectoral fins. The male has a patch of erectile hooks on the outer part of each pectoral covering an area measuring 5 by 1¼ inches on one side, and 4½ by 11/8 inches on the other in a specimen 52 inches long; otherwise the pectorals are smooth for the most part. The front angle of the disc is sharper than in our other skates, being more acute than a right angle, but the tip of the snout is blunt. The outer corners of the pectorals are angular and the disc as a whole is diamond or lozenge-shaped. The two dorsal fins are separated by a short interspace, with one or more spines, and the tip of the tail extends farther beyond the second dorsal fin than it does in most skates. The teeth of the female are flat and pavement-like, but those of adult males are provided with sharp slender cusps. Thirty to forty series of teeth have been counted in the upper jaw, 28 to 38 series in the lower jaw.

Color—

The barn-door skate like so many sea fish, varies in color. The upper surface is brown (as a rule usually of a distinctly reddish hue), variously marked with small scattered darker spots or blotches of varying size, and often with pale marblings or waterings; usually there is a large oval spot on the base of each pectoral fin, in line with the outer angle. The lower surface is not as uniformly pale as it is in most skates, its gray or white ground being shaded with darker toward the snout, and speckled on one-third grown specimens and larger, with black or dusky dots or short streaks that mark the mucous pores, a conspicuous feature.

Size—

The barn-door skate is our largest, growing to a length of 5 feet; it has been said to reach 6 feet though there is no definite record of one that large. One of 58 inches was 42 inches wide with a tail 27 inches long, and a female of 50 inches taken by us, was 33¼ inches wide, with a 22-inch tail. Barn-door skates weigh about 4 to 6 pounds when 28 to 30 inches long, about 10 to 11 pounds at 36 inches, and about 19 to 21 pounds at 45 to 46 inches. Very small specimens are seldom taken.

Habits—

Barn-door skates are bottom fish. They prefer smooth to rocky ground, and we have caught them on very soft mud bottoms as well as on sand and gravel. The fact that the lower surface is more or less pigmented instead of white suggests that it hugs the bottom less closely than other skates, and it is a strong, active swimmer, as anyone will agree, who has landed a large one on a hand-line. Its usual depth range is from close to the tide line, down to about 100 fathoms. It is perhaps more plentiful at 25 [page 62] to 35 fathoms on Georges Bank and on Nantucket Shoals than deeper, judging from average catches of 32 per haul at 26 to 35 fathoms, 13 per haul at 36 to 49 fathoms, and 6 per haul at 50 to 75 fathoms in 42 trawl hauls by the Eugene H, late June 1951, fishing from Nantucket Lightship to the south-central part of Georges Bank. But the Atlantis found it widespread (though not numerous), as deep as 100 fathoms both in the open trough of our gulf and in the bowl west of Jeffreys Ledge during experimental trawling, in August 1936; and it has been reported as deep as 235 fathoms off Nantucket.

The temperature range of the barn-door skate is wider than that of the little skate (p. 67). They are found in the southern side of the Gulf of St. Lawrence in the icy-cold-bottom water on the banks, also, at lesser depths that warm in summer to 60°F. (16°C.) or more. In the Gulf of Maine, at one locality or depth or another, they are exposed to temperatures ranging from perhaps as low as 32° to as high as 64° to 68° and the upper limit must be considerably higher in the southern part of their range.

Garman has pointed out that the spines on the snout of this skate are usually worn smooth, as though used to dig in the mud or sand (very likely it thus obtains the bivalves that form part of its diet). It also feeds on worms, various crustaceans, particularly on large rock crabs and lobsters, shrimps, squid, and on fish. Probably it is more destructive to the latter than are any other of our skates thanks to its large size. Woods Hole records list spiny dogfish, alewives, herring, menhaden, butterfish, launce, cunners, tautog, sculpins, silver hake, hake, and flatfish among its foods. No doubt cod, haddock, and other fish, suffer to some extent from this skate on the off- [page 63] shore fishing grounds, for its European relative is a well-known enemy of the cod, and there is no reason to suppose that the barn-door skate is less voracious. It bites readily on almost any bait, and is often caught on hand and long lines as well as in otter trawls, and in weirs along shore.

Little is known of the breeding habits. The yellowish or greenish brown egg cases are about 47/8 to 51/8 inches (124-132 mm.) long by 25/8 to 27/8 (68-72 mm.) inches broad, not counting the horns, and thus much larger than those of any other Gulf of Maine skate. Females containing fully formed egg capsules have been taken in December and January in Nova Scotia waters, evidence that the eggs are laid in winter. However, it seems that the young are not hatched until late spring or early summer, for we have seen one, taken on Nantucket Shoals in July, so small (about 73/8 in. long) that it could not have been set free long before its capture.

General range—

Atlantic Coast of North America from the Banks of Newfoundland, Gulf of St. Lawrence and outer coast of Nova Scotia and the Nova Scotia Banks to North Carolina.^[64] It is replaced in European seas by a very close ally, the common skate, Raja batis.

Occurrence in the Gulf of Maine—

This is a common fish in all parts of our Gulf, and any very large skate taken or reported there is almost certain to be a "barn-door." Following the coast around from east to west we find it reported as plentiful off the outer Nova Scotia shore; it is known from St. Mary Bay; is found very generally though not abundantly in the Bay of Fundy and in Passamaquoddy Bay; is reported from Eastport, Casco Bay, and generally along the coast of Maine; is known from various localities in Massachusetts Bay, where we have seen many caught; and its abundance on Georges Bank and on Nantucket shoals is illustrated by an average catch of about 21 per haul (about 14 percent of all the skates caught), in 42 trawl hauls by the Eugene H, fishing from Nantucket Lightship out into the south central part of Georges Bank in late June 1951. In short, it is to be expected anywhere within the limits of the Gulf. Like most other skates, it is often taken in shoal water in our Gulf in summer; seldom or never in winter. Huntsman tells us that it comes to Passamaquoddy Bay from May to November. We once caught one nearly 5 feet long at Cohasset in Massachusetts Bay in less than a fathom of water in midsummer; indeed, it is often stranded on the beach. This inshore migration, however, does not involve the entire stock, witness its presence in 20 to 60 fathoms on Georges Bank and off Cape Cod throughout the year, and the fact that it is reported by fishermen and has been trawled by vessels of the former Bureau of Fisheries, also by the Atlantis, as deep as 100 fathoms in summer. In the warmer waters off the southern coast of New England it comes inshore in spring and autumn, descending to somewhat deeper water for the summer.

Commercial value—

The barn-door skate is of no commercial value except as entering into the small landings of skates mentioned on page 61.