46 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Size. — It appears that hammerheads are com- 

 monly about 19 to 20 inches long when they are 

 born; seemingly, they mature sexually at about 7 

 to 8 feet; they are often taken 9 to 11 feet long, 

 and occasionally as long as 12 to 13 feet. 12 Most of 

 those that visit southern New England are less 

 than 6 to 7 feet long, some very small indeed. 13 

 In 1805, however, one of 11 feet was netted at 

 Riverhead, L. I. And the fact that it contained 

 parts of a man in its stomach has been chiefly 

 responsible for the bad reputation of this species 

 of hammerhead. 



Two other large sharks closely related to the 

 common hammerhead, the tropical hammerhead 

 (Sphyrna lewini Griffith, 1834) u and the great 

 hammerhead (Sphyrna mokarran Ruppell, 1835) 16 

 occur along the South Atlantic coast of the United 

 States. The first of these, in particular, might 

 stray as far as Cape Cod, as many tropical fishes 

 do, for it has been recorded from the offing of 

 Cape May, New Jersey. They resemble the com- 

 mon hammerhead closely in general appearance, 

 but both of them may be distinguished from the 

 latter by the fact that the front outline of their 

 head is scalloped in the midline, not evenly 

 rounded there as it is in the common hammerhead. 

 For further accounts of them, see Bigelow and 

 Schroeder. 16 



Habits. — Since hammerheads are an accidental 

 visitor to the Gulf, we need only remark that 

 they are pelagic in habit, often swimming with 

 dorsal and caudal fins out of water, and are to be 

 met with indifferently out at sea or near land. 

 They feed chiefly on fish, including smaller 

 sharks (including their own kind), and sting rays, 



11 The larger hammerheads that are sometimes reported probably are not 

 this species, but the great hammerhead (Sphyrna mokarran, p. 46, note 16). 



'» Dozens of little ones, of about 2H feet, have been seined on the outer shore 

 of Long Island, N. Y., In August. 



" The account of this species, In Bigelow and Schroeder, (Fishes of the 

 Western North Atlantic, Pt. 1, 1948, p. 415) was as diplana Springer, 1941. 

 But Fraser-Brunner (Rec. Austral. Mus., vol. 22, No. 3, 1950, pp. 213-214), 

 has shown that It cannot be separated from the Indo-Paclflc S. leuinl of 

 Griffith, 1834, a much older name. 



i* Tortonese has recently pointed out (Ann. Mag. Nat. Hist. Ser. 12, vol. 3, 

 No. 36, 1950, p. 214) that the name tudes Valenciennes 1822 that has been 

 applied commonly to the great hammerhead of the Atlantic actually belongs 

 to a different species; consequently that the correct name of the great hammer* 

 head Is mokarran RQppell, 1835, It being Identical with that Indo-Paclflc 

 species. 



n Fishes Western North Atlantic, Pt. 1, 1948, pp. 415, 428. 



the tail spines of which are sometimes found 

 imbedded in their jaws. Like tiger sharks, they 

 make themselves a pest in warmer latitudes where 

 fisheries for sharks are carried on, by devouring 

 those that they find entangled in the nets. As 

 many as 30 to 37 embryos have been found in a 

 gravid female, and the embryos do not develop any 

 placental connection with the mother, so far as is 

 known. 



General range. — Widespread in the tropical to 

 warm temperate belts of the Atlantic, of the 

 Pacific, and probably of the Indian Ocean as 

 well; north commonly to southern New England, 

 straying to Massachusetts Bay and as far as 

 Halifax, Nova Scotia. 17 



Occurrence in the Gulf of Maine. — Hammer- 

 heads (often in small schools) wander northward 

 every summer, along the Atlantic seaboard; they 

 are often to be seen basking at the surface (some 

 harpooned) a few miles out, off Marthas Vine- 

 yard and Nantucket; and one is occasionally 

 taken in one or another of the fish traps near 

 Woods Hole. But the longitude of Cape Cod so 

 sharply bounds their yearly dispersal that the 

 only records from the Gulf of Maine, or from 

 Nova Scotia waters, are of stray specimens from 

 Chatham and Provincetown on the outer shores 

 of the Cape; of one about 27 inches long from 

 Nahant, in the inner part of Massachusetts 

 Bay ; I8 of two small ones recently from Casco 

 Bay; 19 of one taken many years ago, off Brier I., 

 on the Nova Scotian side of the Bay of Fundy; 20 

 of a 12-footer harpooned between Georges and 

 Browns Banks in August 1928 by the sword 

 fishing schooner Doris M. Hawes; of a small one 

 caught in Halifax Harbor, Nova Scotia, in 

 September 1932; 21 and of another about 21 inches 

 long taken in a trap off Sambro Head, near Hali- 

 fax, August 25, 1938. 22 



" For further details of distribution, see Bigelow and Schroeder, Fishes of 

 the Western North Atlantic, Pt. 1, 1948, p. 442. 



18 This specimen, obtained many years ago by Louis Agasslz, Is In the 

 Museum of Comparative Zoology. 



'• Seen In the flsh market at Portland, Maine, by the late Walter H. Rich. 



» McKenzle, Proc. Nova Scotia Inst. Sci., vol. 20, 1939, p. 13. 



" Vladykov, Proc. Nova Scotia Inst. Sci., vol. 19, Pt. 1, 1935. p. 8. 



" McKenzle, Prov. Nova Scotia Inst. Sci., vol. 20, 1939, p. 13. 



