Big skate Raja ocellata Mitchill 1815

SPOTTED SKATE; WINTER SKATE; EYED SKATE

Description—

This skate looks very much like the little skate, but it is larger and has more numerous teeth. The front angle of the disc is much blunter than a right angle, bulging opposite the eyes, and the tip of the snout is rounded. The teeth are in from 72 to 110 series in each jaw instead of 66 series, or fewer as in erinacea, and they are sharper in males than in females. The backs of both sexes are rough with sharp spines on the head, around the eyes, along the anterior margins of the pectorals, over the shoulders, and on the sides of the tail. The midline of the back behind the shoulders is almost always free of spines in adults. But we have one specimen, a female 18 inches long taken near Jeffreys Ledge, November 1, 1927, which bears a row of large spines along the midline of back and tail from the shoulder girdle to the first dorsal fin. Males, like those of other skates, have rows of retractile hooks on the outer parts of the pectorals. The two dorsal fins are close together; the outer corners of the pectorals are bluntly angular; the claspers of adult males reach about halfway back along the tail, which occupies about half the total length of the fish.

Color—

Light brown above with round dark brown spots. As a rule there is a large white eye spot with black center near the rear corner of the pectoral fin, and often two smaller ones [page 64] close to it. And we have seen two large specimens from Georges Bank with several of these eye spots on each side of the disk. There is a translucent or white area on each side of the snout in front of the eyes and the lower surface is white.

The eye spots, if present, serve to identify this skate at a glance; sometimes, however, they are lacking, in which case half-grown specimens so closely resemble the little skate that recourse must be had to the number of teeth to tell the one from the other.

Size—

This skate does not mature until at least 25 to 26 inches long, and grows to about 3½ feet in length, commonly from 30 to 34 inches. Specimens 32 inches in length are about 20 inches wide.

Habits—

Big skates feed on the same diet as little skates do (p. 69). Rock crabs and squid are favorite prey, but they also take annelid worms, amphipods, shrimps, and razor clams, and they eat whatever small fish are readily available, the list at Woods Hole including smaller skates, eels, herring, alewives, bluebacks, menhaden, smelt, launce, chub mackerel, butterfish, cunners, sculpins, silver hake, tomcod, and hake.^[65]

It is caught right up to the wharves in the Gulf of St. Lawrence; often comes into very shoal water on sandy beaches, and we once caught an adult male in September in only 2 or 3 feet of water in Nauset Marsh on the outer coast of Cape Cod, but few are found shoaler in our Gulf than 2 to 4 fathoms. They are much more plentiful at 25 to 35 fathoms than deeper, on the offshore grounds, as appears from average catches, of 48 per haul at 26 to 35 fathoms, but only 11 per haul at 36 to 49 fathoms, and none at 50 to 75 fathoms, in 42 trawl hauls by the Eugene H, fishing -from Nantucket Lightship to the south-central part of Georges Bank in late June 1951, and very few are caught deeper than about 50 fathoms anywhere.

In our Gulf they inhabit about the same range of temperature as the little skate does, i. e., from 68° or so, for those along the Massachusetts coast in summer, down to 34-36° in the coastal belt as a whole in winter, and to near 32° in the Bay of Fundy region, at least in some years. In the southern side of the Gulf of St. Lawrence they are found in the icy bottom water on the banks as well as shoaler, where temperatures rise to 61° (16° C.) or more in summer. Those living the shoalest in the southern part of their range [page 65] must be exposed to temperatures as high, perhaps, as 68° to 70° at the warmest time of the year.

Off the Atlantic Coast of Nova Scotia this skate deposits its eggs from summer into autumn, and probably through the same season in the Gulf of Maine for Scattergood^[66] reports females with egg capsules in Maine waters in September. And it continues to do so into December and January off southern New England. Its egg cases are larger than those of the little skate, 2½ to 2¾ inches by about 1¾ inches, not counting the horns. The length of the period of incubation is not known.

General range—

Atlantic Coast of North America from northern North Carolina to the southern side of the Gulf of St. Lawrence, and to the southern part of the Newfoundland Banks.

Occurrence in the Gulf of Maine—

This, the second in size of our skates, occurs commonly all around the Gulf of Maine from Nova Scotia to Cape Cod. There are many locality records for it for the Bay of Fundy as well as from the coasts of Maine and Massachusetts, but so closely does a half or two-thirds grown big skate resemble an adult little skate (p. 68) that it is often impossible to tell to which species published reports refer. It also makes up so considerable a proportion of the skate population on Georges Bank that about 14 percent of the catch of skates made on Georges Bank by one otter trawler in September 1929, and about 18 percent (1,116) of the skates taken in 42 trawl hauls by the Eugene H, late June 1951, fishing from Nantucket Lightship to the southwestern part of Georges Bank, were this species. But it has never been reported from the deeper troughs of the Gulf, nor have we taken it there.

The name "winter skate" seems appropriate enough for it along the southern coast of New England, for it is only during the cold season that big skates come close inshore near Woods Hole. And they are said to be taken in larger numbers in winter than in summer in the Massachusetts Bay region (we cannot verify this). However, this is a misnomer in the cooler waters of the northern part of the Gulf of Maine, for it is common inshore in Passamaquoddy Bay from May to November, and this probably applies to the whole coastline east of Cape Elizabeth to judge from temperature.

Big skates are taken on hook and line, in weirs, and in otter trawls, but they are of no commercial value, except as they form a part of the general landings of skates. And they are only a nuisance to anglers.