FISHES OF THE GULF OF MAINE 



39 



overlap. The median upper tooth is nearly 

 symmetrical, but those along the sides of the 

 mouth have strongly convex outer margins, and 

 deeply concave inner margins, while their points 

 curve sharply outward toward the respective 

 corner of the mouth. The lower teeth are nar- 

 rower, more nearly symmetrical, and nearly 

 erect. 



Color. — Living specimens are dark indigo blue 

 along the back, shading to a clear bright blue *° 

 along the sides; but this beautiful hue changes to 

 a slaty or sooty gray soon after death. The lower 

 surface is snow-white, but with the tips of the 

 pectorals dusky and the anal fin partly sooty. 



Size. — The usual length at birth seems to be 

 between VA and 2 feet. 91 Blue sharks do not ma- 

 ture until they have grown to be 7 or 8 feet long, 

 to judge from the sizes of the females that have 

 been found with young; the longest we have 

 handled was almost exactly 11 feet long. The 

 fact that the greatest measured length so far re- 

 liably reported was only 12 feet 7 mches (3.83 

 meters) suggests that repeated characterizations 

 of the blue shark as commonly growing to 15 feet 

 are an exaggeration. If any grow to 20 feet, as 

 is rumored, they must be giants of their kind. 



Remarks. — The very long slender pectorals of 

 the blue shark, combined with its long narrow 

 snout, the position of its first dorsal fin far back, 

 and its brilliant blue color, give it an aspect 

 very different from that of the tiger shark (p. 37), 

 of the sharp-nosed shark (p. 40), the dusky or 

 brown sharks (pp. 41-43), or that of any other 

 carcharhinid shark that might perhaps straggle to 

 the Gulf of Maine. 



Habits. — The blue shark is "encountered indif- 

 ferently far out at sea and in continental waters, 

 its wanderings no doubt directed chiefly by the 

 search for food, though it may drift with ocean 

 currents. It is frequently seen at the surface, 

 swimming lazily with first dorsal fin and tip of 

 caudal out of water, or basking in the sun. There 

 is no reason to suppose that it ever descends to 

 any great depth." 92 They sometimes follow sail- 

 ing ships for days on end, to pick up scraps, and 

 their habit of gathering when a sperm whale was 



killed, to feed on the carcass, was proverbial dur- 

 ing the days of the sperm whale fishery. 93 But 

 their normal diet is smaller fishes, of whatever 

 kinds may be available. In northern waters 

 herring, mackerel, spiny dogfish, and various 

 others have been found in their stomachs. And 

 we have several times seen a blue shark pick up 

 a tagged cod, haddock or American pollock that 

 we had put back in the water, on Georges Bank. 



The blue shark is viviparous, that is to say, the 

 embryo has a well developed placenta attached to 

 the mother. As many as 28 to 54 young have 

 been reported in a litter in the Mediterranean. 



General range. — Cosmopolitan on the high seas 

 in the warmer parts of all the oceans, including 

 the Mediterranean; ranging northward to outer 

 Nova Scotia and as a stray to the Banks of New- 

 foundland in the western side of the Atlantic; to 

 England and Scotland in the east, with stray 

 specimens reaching the Orkneys and southern 

 Norway. This, we think, is by far the most nu- 

 merous of the large, oceanic sharks; it is the one 

 witli which the sperm whalers were the most 

 familiar; the one around which many of the super- 

 stitions about sharks have developed; and the one 

 with which we have had to do most often. 



Occurrence in the Gulj oj Maine and along Nova 

 Scotia. — Only one blue shark had been reported 

 definitely from the Gidf of Maine in scientific lit- 

 erature, up to the time the first edition of this book 

 was printed, though it was known to be rather com- 

 mon along outer Nova Scotia. But we have 

 learned since then that it is a regular summer visi- 

 tor to the southern and western parts of the Gulf, 

 appearing occasionally in July, more often in Aug- 

 ust and September. In 1928, for example, we 

 caught one on Stellwagen Bank on August 26, saw 

 one over the northern end of Jeffreys Ledge on 

 September 2, and caught four on Platts Bank on 

 September 3, with others in sight from the vessel at 

 nearly all times throughout the day. And many 

 more have been seen or caught subsequently, on 

 Platts Bank, in Massachusetts and Cape Cod Bays, 

 where 1 8 were reported to us during the summer of 

 1935, 9 * on Georges Bank where blue sharks, swim- 

 ming at the surface, are a familiar sight in summer; 

 and on Browns Bank. Two have also been re- 



" "Sailor blue," as shown in Rldgeway's Color Standards and Color 

 Nomenclature, 1912, p. 21. 



" Embryos have been reported as long as about 17H inches, and free-living 

 specimens as small as 20-21 inches. 



•* Blgelow and Schroeder, Fishes Western North Atlantic, Pt. 1, 1948, p. 

 286. 



»» Nichols and Murphy (Brooklyn Mus. Scl. Bull., vol. 3, No. 1, 1916, p. 

 9) have given a graphic account of the blue shark as it was met with by 

 whalers on the high seas. 



" By J. E. Lowes, an experienced shark fisherman. 



