36 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



million crabs, besides a great number of small 

 fish (menhaden and tautog are the species most 

 often found in smooth dogfish stomachs). And 

 these figures are based on a sufficient number of 

 observations of the stomach contents to serve as a 

 general indication of the destructiveness of the 

 smooth dogfish. They also feed on squid, espe- 

 cially in spring, and while they do not regularly 

 take hard-shelled mollusks, razor clams have 

 been found in the stomachs of several at Woods 

 Hole. When kept in captivity they are constantly 

 on the move, searching the bottom for food, which 

 they find chiefly by the sense of smell though 

 their sight is also keen. 81 Any crab that may be 

 offered is soon found, seized, shaken to and fro, 

 and eaten. And with packs of these sea hounds 

 hunting over every square foot of our southern 

 bays and sounds it is a wonder any of the larger 

 crustaceans escape where dogfish are abundant. 

 Field 82 also made the interesting observation 

 that the smooth dogfish never molested healthy 

 and active menhaden but soon devoured any sick 

 or injured fish that might be in the same tank 

 with them. 



As this is not a characteristic Gulf of Maine 

 fish, we need merely note that it is one of the 

 sharks that develop a placental connection be- 

 tween the embryos and the mother. In other 

 words, it is truly viviparous. The period of 

 gestation appears to be about 10 months; off 

 southern New England the young are born be- 

 tween early May and mid July. The number in a 

 litter usually is between 10 and 20, but as few as 

 4 have been reported. A description of the un- 

 born young is given by Fowler. 83 



General range. — Coastal waters of the western 

 Atlantic, from Uruguay and southern Brazil, 

 regularly to Cape Cod, and to Passamaquoddy 

 Bay as a stray; also Bermuda. 84 



Occurrence in the Gulj of Maine. — The smooth 

 dog is the second most numerous shark along the 

 southern coast of New England, though falling 

 far short of the spiny dogfish (p. 50). At Woods 

 Hole, for example, pound-net catches varied 

 during the summer of 1903 from 1 to 41, averaging 

 about 7, and catches up to 100 have been reported 

 from the vicinity at one time. Similarly, catches 

 of 5 or 6 on a hand line are common in a few hours' 

 fishing, with as many as 10 to 20 reported. But 

 the elbow of Cape Cod and the region of Nan- 

 tucket Shoals mark so definite a boundary to their 

 dispersal eastward that while they have been 

 reported from Provincetown, from various locali- 

 ties within Massachusetts Bay, and even from as 

 far north as St. Andrews in the Bay of Fimdy, 

 where one was caught in July 1913, neither of us 

 had ever seen one north of Cape Cod until Sep- 

 tember 21, 1951, when an angler (Ellery Sidney) 

 showed us a female about 3 feet long that he had 

 caught at Cohasset, while casting with an eel 

 skin, for striped bass. So far as known its 

 occasional incursion- into the Gulf are sporadic, 

 at least they have not been correlated with 

 unusually warm summers or with the presence of 

 other southern fishes. Neither has it been re- 

 ported by fishermen from Georges or Browns 

 Banks, nor was it detected there by the repre- 

 sentatives of the Bureau of Fisheries during the 

 trawling investigations of the years 1912 and 1913 

 (p. 60), or subsequently. 



REQUIEM SHARKS. FAMILY CARCHARHINIDAE 



This family, which includes a large number of 

 species in tropical and temperate seas, is charac- 

 terized by a head of normal shape, eye with a 

 nictitating (winking) membrane, tail with the 

 upper lobe considerably larger than the lower but 

 not very long, 2 spineless dorsal fins, the first 

 usually much larger than the second in most of 



61 The senses of this shark have been studied by Parker (Bull., U. S. Bur. 

 of Fish., vol. 29, 1911, pp. 43-57), and by Sheldon (Jour. Compar. Neurol, 

 and Psychol, vol. 19, 1909, No. 3, p. 273). 



»» Rept. U. S. Comm. Fish., (1006), 1907, Spec. Pap. 6, pp. 14-16. 



13 Occas. Pap. Mus. Zoo]., Univ. Mich., No. 56, 1918, p. 15. 



the Atlantic species, 86 an anal fin, a caudal peduncle 

 lacking lateral keels, and sharp, bladelike teeth 

 with a single cusp. All bear "living" young; 



" Present indications are that several more or less isolated populations of 

 this shark exist, with their areas of regular occurrence separated by wide 

 gaps, where Ihere is little or no intermingling. One of the best known is 

 along the Atlantic coast, Cape Cod to North Carolina; another centers in 

 the Gulf of Mexico-Caribbean region; a third is along southern Brazil and 

 Uruguay. For further details, see Bigelow and Schrocdcr, Fishes Western 

 North Atlantic, Part 1, 1948, pp. 250-251. 



85 The lemon shark (Negaprion brtpirosiris) of warmer waters, which has 

 been known to stray to New Jersey, is an exception in this respect; its second 

 dorsal is nearly as large as its first dorsal. 



