FISHES OF THE GULF OF MAINE 



21 



Figure 5. — Mackerel shark (Lamna nasus), about 37 inches long, Xahant, Massachusetts. Upper and lower first to 

 fifth teeth from center of jaw of a larger specimen from Platts Rank, about 0.7 times natural size. From Bigelow 

 and Schroeder. Drawings by E. N. Fischer. 



Color. — Dark bluish gray to bluish black above, 

 including the upper surfaces of the pectorals, 

 changing abruptly, low down on the sides, to white 

 below; lower surfaces of pectorals dusky to black 

 on the outer one-half to one-third, more or less 

 mottled while and dark toward their bases, and 

 with the anterior and posterior edges narrowly 

 rimmed with black; the anal is white or slightly 

 dusky. 



Size. — The common run of mackerel sharks in 

 the Gulf of Maine are from 4 to 6 feet long, with 

 few heavier than 200 pounds; thus 18 recently 

 landed at Portland and East port, Maine,'" averaged 

 4 feet 5 inches, the largest being about 8 feet long, 

 the smallest 3 feet 7 inches. 



Specimens longer than 7 to 8 feet are not 

 common; only two longer than 8 feet have been 

 recorded previously from the Gulf of Maine, one 

 of which was 10 feet, 32 the largest recorded 

 from either side of the North Atlantic. This shark 

 has been said to reach a length of 12 feet. But 

 the sizes of sharks often are overstated, uidess 

 actually measured, point to point, not around the 

 curve of the body. Information as to the relation- 

 ship between length and weight is restricted to a 

 report of 305 pounds at 8 feet 3 inches, and of 

 about 400 pounds at about 9 feet. One 3 feet long 

 that we measured weighed 20 pounds. 



» Scattergood, Copela, 1949, No. 1, pp. 71-72. 

 « Hubbs, Copela, No. 1?3, 19?3, p. 101 



Habits. — The whole mackerel-shark tribe lead a 

 pelagic life, wandering about over the ocean in 

 pursuit of the fishes on which they prey, and 

 often uniting in small companies, though the, 

 can hardly be called gregarious. Like swordfish 

 they spend much time at the surface on calm days, 

 when their triangular back fins, followed by the 

 tip of the caudal fin (the bluntness of the former 

 and the wavy track of the latter identify the 

 shark as such) may often be seen cutting through 

 the water. We have sailed close to sharks probably 

 of this species again and again, only to see them 

 sound, just out of harpoon range, plainly visible 

 at first but soon fading from sight as they swim 

 downward. 



The porbeagle has often been described as 

 active and strong swimming. But it puts up 

 only a very feeble resistance when hooked. 

 We have never seen or heard of one jumping, as 

 the mako often does (p. 24), nor is there any 

 difficulty in landing one of 4 to 5 feet on an 

 ordinary cod line. It is, in fact, as proverbial 

 among fishermen for its sluggishness when hooked, 

 as is the mako for its activity. While often seen 

 "finning," many are caught close to the bottom, 

 in depths down to 80 fathoms in the gill net 

 fishery for ground fish that is carried on from 

 Portland, Maine; some also on bottom on cod 

 lines; how much deeper they may descend is 

 not known. 



