16 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



the mackerel shark (Larrma nasus), and the blue 

 shark (Prionace glauca), occur with us in numbers 

 sufficient for one to be fairly sure of seeing them 

 during a summer's boating off the coast north of 

 Cape Cod. 



With the larger sharks generally so scarce (the 

 mackerel shark is harmless to anything larger than 

 the fishes on which it feeds, and the blue 

 shark is also harmless, although better armed), 

 the danger of attacks on bathers is negligible in 

 our Gulf. Indeed, not a single well-authenticated 

 instance of the sort is on record w for the past 

 80 years for the coast north of Cape Cod, though 

 the beaches are crowded every summer with 

 vacationists. But as long as the white shark or 

 man-eater (Carcharodon carcharias) does stray 

 occasionally into the Gulf (p. 26), it is always 

 remotely possible that we may be horrified some 

 summer by the news of tragedies such as occurred 

 on the New Jersey coast in July 1916, when 

 several persons were killed or injured, presumably 

 by a small shark of this species that was captured 

 nearby a few days later, 28 and near Mattapoisett, 

 on Buzzards Bav, Mass., on July 25, 1936, when 

 a swimmer was fatally injured by a shark, species 

 not determined. 29 



17 In 1830 (an event often quoted) one Joseph Blaney, fishing from a small 

 boat In Massachusetts Bay off Swampscott, Mass., was attacked by some 

 fish that was seen to overset and sink his boat and, presumably, devoured 

 him, for neighboring fishermen who hastened to his rescue found no trace of 

 him. Whether his attacker was a large shark or a killer whale is an open 

 question. 



" Murphy and Nichols (Brooklyn Mus. Quart., vol. 3, 1916, No. 4, pp. 

 145-160) give a detailed account of this occurrence. 



» See Oudger (Amer. Midland Natural., vol. 44, 1050, p. 714) for clinical 

 details of this case. 



All Gulf of Maine sharks give birth to young 

 that are not only practically adult in structure 

 but of relatively large size at birth, and there is a 

 placental connection between mother and embryo 

 in some, but not in others. Still other sharks lay 

 eggs; this is true of the chain dogfish {Scyliorhinus 

 retifer, p. 34), which is common out on the conti- 

 nental shelf from the offing of Cape Cod, south- 

 ward, and of its immediate relatives; also of the 

 heterodontids or Port Jackson sharks which are 

 not represented in the Atlantic. 



There is so little market for sharks in Gulf of 

 Maine ports (attempts to introduce the dogfish as 

 a food fish having failed so far) that the amounts 

 landed in Maine and Massachusetts were only 

 about 240,000 pounds in 1947, and about 309,500 

 pounds in 1949; they interest fishermen chiefly as 

 nuisances because of the damage they do to nets 

 and other gear, except that mackerel sharks are 

 marketable. 



It is possible to identify all the sharks so far 

 known from the Gulf (and this includes all that 

 are likely to occur there except strays) bv the 

 sizes and relative locations of the fins, and by 

 such tooth characters as may be seen at a glance 

 at the open mouth or easily felt with the finger 

 (after the shark is dead!). 



We have attempted in the following descriptions 

 of the several species to include only such features 

 as will tell what shark is at hand ; for more minute 

 particulars we refer the reader to our account of 

 the sharks of the western North Atlantic (p. 2). 



Key to Gulf of Maine Sharks 



1. There is an anal fin 2 



There is no anal fin 16 



2. Head greatly expanded sidewise, at level of eyes, in hammer- or shovel-form 3 



Head of ordinary shape, with rounded or pointed snout 4 



3. Outline of front of head only slightly concave opposite nostrils if at all so; grooves (if any) from nostrils shorter than 



horizontal diameter of eyes; free tip of second dorsal fin is not longer than forward margin of the fin; rear margin 

 of anal fin is only weakly concave; teeth near outer corners of mouth are rounded, without sharp cusps. 



Shovel head, p. 44 



Outline of front of head is deeply indented opposite each nostril ; grooves from nostrils are more than twice as long as 



horizontal diameter of eye; free tip of second dorsal fin is considerably longer than front margin of the fin; rear 



margin of anal fin deeply concave; teeth near corners of mouth are like those near center of mouth, with sharp 



cusps Hammerhead, p. 45 



4. Caudal peduncle (root of tail) is not widely expanded sidewise as a lateral keel on either side; upper lobe of caudal 



fin is much longer than lower lobe 8 



Caudal peduncle is widely expanded sidewise as a lateral keel on either side; lower lobe of caudal fin is nearly as long 

 as upper lobe, suggesting the caudal fin of a mackerel or swordfish 5 



