60 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



on La Have Bank in 1890, 68 and from Eastport, 

 Maine, at the mouth of the Bay of Fundy. It 

 has also been taken at Williamsport, Maine; off 

 Seguin Island where one was examined in 1880; 

 at the mouth of Casco Bay; at Wood Island near 

 Cape Elizabeth (1, in a trap, in 1894); near Cape 

 Ann; off Plymouth in the southern side of Massa- 

 chusetts Bay; near Provincetown; and on the 

 outer coast of Cape Cod, so it would be no sur- 

 prise to find it anywhere along the shores of the 

 Gulf. It has been caught occasionally on Georges 

 Bank; 69 there are records of long standing of 

 torpedos off Nantucket and Marthas Vineyard, 

 and they are caught yearly in Vineyard Sound 

 and in Buzzards Bay. 



Most of the reports of torpedoes within the 

 Gulf have been based on single specimens. But it 

 has been known for a long time that torpedoes 

 are caught in much larger numbers in some years 

 than in others. Thus they are said to have been 

 unusually common near Provincetown in 1819 

 and for the next 4 or 5 years, when 60 to 80 were 

 taken there yearly. Again in 1845 about a dozen 



came ashore or were caught otherwise near 

 Provincetown. Any fluctuation, however, that 

 may have taken place from year to year thereafter 

 seems to have attracted no attention until the 

 summer of 1896, when Dr. W. C. Kendall, of the 

 U. S. Fish Commission collected several along the 

 coast of Maine. The Massachusetts Bay speci- 

 men mentioned above, taken off Plymouth and 

 now in the Harvard Museum of Comparative 

 Zoology, is the only torpedo from the inner part 

 of the Gulf of which we have heard since that 

 time. But it is as likely to be found in the Gulf 

 now as it ever was. 



Importance. — The torpedo is of no commercial 

 value nowadays, but its liver oil was considered 

 equal to the best sperm for illuminating purposes 

 before the use of kerosene oil was general. There 

 is an old tale that its oil was a good cure for 

 cramps if rubbed on externally, for stomach 

 trouble if taken internally. And when one is 

 landed on the dock at Woods Hole it is an object 

 of interest to the workers at the Biological Labora- 

 tory because of its electric discharges. 



SKATES. FAMILY RAJIDAE 



Skates, with their disc-like outlines, thin as a 

 shingle toward their outer edges, and with their 

 rather long tails, are familiar objects along our 

 shores. The outer edges of their pelvic fins are 

 concave (convex in the sting rays) , they have two 

 very small dorsal fins on the rear part of the tail, 

 but no distinct tail fin, and they lack the large 

 tail spine that is so characteristic of the sting rays. 

 The Gulf of Maine supports four species in abun- 

 dance, while two others have been recorded on 

 rare occasions. 



The common skates look so much alike that 

 fishermen seldom distinguish between them. For 

 this reason we know very little about the indi- 

 vidual differences in habits among the several 

 species. All live chiefly on the bottom or close to 

 it, spending much of the time partially buried in 

 the mud or sand. They move through the water 

 by undulations of the flexible pectoral fins, steering 

 themselves with the tail. All are decidedly om- 

 nivorous, feeding largely on the larger Crustacea, 



" Reported by Q. F. O. Hansen, then second mate and later master of the 

 U. S. Fish Commission schooner Oramput, who doubtless was acquainted 

 with the torpedo at Woods Hole. 



•> The most recent record is of one 58 inches long, trawled on the southwest 

 part in December 1930. 



such as shrimps, crabs, lobsters; on mollusks, 

 worms, and to a greater or less extent on fish. 



All the true skates lay large eggs with blackish 

 or sea-green leathery shells, roughly oblong in 

 outline, with a hollow tendril at each corner by 

 which they become fastened to seaweeds or other 

 objects. The empty eggshells, " mermaids purses," 

 are familiar objects on our beaches among the 

 flotsam along high water mark. While still in 

 the egg the embryo skate develops temporary 

 external gill filaments from the walls of the gill 

 clefts, but these disappear completely before it 

 hatches. Probably all our local skates spawn 

 over a considerable part of the year, with incuba- 

 tion periods of several months up to a year or 

 more. 60 



To give some idea of their abundance on the 

 offshore banks we may note that the average 

 number of skates (all species together) taken on 

 Georges Bank, per trip of 4 to 7 days, on 25 

 trips by several trawlers, January to December 

 1913, was about 800, the largest catch 4,520, the 



w Under aquarium conditions the incubation period for the little skate 

 (R. trinacea) was 5 to 6 months (p. 69); and it ranged from 4H to about HH 

 months for 6 common European skates; see Clarke, Jour. Marine Biol. 

 Assoc. United Kingdom, vol. 12, No. 4, 1927, p. 687. 



