FISHES OF THE GULF OF MAINE 31 



8. Hammerhead shark {Cestracion zygsena Linn.-Bus) 



Jordan and Evermann {Sphyrna zygsnia Linnseus), 1896-1900, p. 45. 

 Garman, 1913, p. 157. 



Description. — The bizarre outline of the head of the hammerhead, easier 

 drawn than described, has been so widely heralded that probably everyone at all 

 concerned with fishes is perfectly familiar with it. It can not possibly be confused 

 with that of any other fish. The eyes stand at either edge of the "hammer"; the 

 first dorsal fin originates slightly behind the "armpit" of the pectoral, is con- 

 siderably larger than the latter, and is much higher than long; the very small second 

 dorsal is hardly one-fifth as high as the first; the upper lobe of the tail is notably 

 long (about one-third as long as the body of the fish) and deeply notched near the 

 tip, the lower lobe hardly one-half as long as the upper. 



Size. — The hammerhead is one of the larger sharks, growing to a length of 15 

 feet or more. 



Color. — Gray to ashy brown above; paler brown to dirty white below. 



General range. — A warm-water species, cosmopolitan in tropical seas north- 

 ward to the Gulf of Maine in the western North Atlantic, and to British waters in 

 the eastern North Atlantic. 



FiQ. 9. — Hammerhead shark ( Cestracion zygxna) 



Occurrence in the Gulf of Maine. — The hammerhead, like most of its tropical 

 relatives, finds Cape Cod and the cool water that it meets when it strays beyond 

 that natural boundary the eastern and northern limit to its regular annual occur- 

 rence. In the Woods Hole region, only a few miles west of the cape, it is caught 

 from time to time in the fish traps from July to October almost every year. So far, 

 however, the only definite reports of it in the Gulf of Maine with which we are 

 acquainted are from Chatham and Provincetown, the latter its most northerly record 

 on the American coast; nor is it likely that the hammerhead is more common in 

 the Gulf than these few records suggest, for so easily recognized is it among sharks 

 that it is far more apt to bo reported than are the various tropical species of more 

 conventional appearance. It would not be surprising to see it on Georges or Browns 

 Bank, though no rumor of its presence there has reached us. 



With the hammerhead, as with many other tropical fishes, the examples that 

 visit the shores of New England are usually small. At Woods Hole about 4 feet 

 is the commonest length and 6 to 8 feet the maximum. In 1805, however, a speci- 

 men 11 feet long was netted at Riverhead, Long Island, N. Y., and the fact that 

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