FISHES OF THE GULF OF MAINE 37 



General range. — North Atlantic and Pacific Oceans. Closely allied to the 

 ommon porbeagle (Isurus nasus Bonaterre) of British seas. 



Occurrence in the Gulf of Maine. — From the days of the earliest settlement it 

 has been known that stout-shouldered, surface-swimming sharks of moderate size 

 and with "mackerel" tails are tolerably common in the Gulf of Maine, universally 

 referred to by the fishing population as "mackerel sharks." During the first half 

 of the last century only one such shark species was recognized in our waters, but 

 more recent researches have proved that there are actually two — the present one 

 and the next — readily separable by the position of the first dorsal fin relative to 

 the pectorals and of the second dorsal relative to the anal, but so much alike in 

 general appearance that it is usually impossible to determine without actually exam- 

 ining the specimens to which species many of the records actually belong. However, 

 since /. punctatus is the more northerly of the pair, and since far more specimens 

 of it than of /. tigris have actually come to hand, probably most of the mackerel 

 sharks that fisherman so often see swimming lazily on the surface off the shores 

 of Northern New England belong here. 



Although these sharks are far more often seen than captured, we have definite 

 record of the common mackerel shark at Provincetown, in Massachusetts Bay, 

 off Cape Ann, and at various localities along the Maine coast — e. g., off Cape Eliza- 

 beth, in Casco Bay, off Monhegan, and even Passamaquoddy Bay in the Bay of 

 Fundy, where, however, Huntsman (1922a) records but a single specimen. During 

 our Grampus cruises we have seen many mackerel sharks, particularly between Cape 

 Ann and the Isles of Shoals, and off Monhegan Island. This shark likewise ranges 

 northward along the Nova Scotian coast and into the Gulf of St. Lawrence. It may, 

 in fact, be described as common, if not abundant, and to be expected anywhere in 

 the Gulf of Maine during the summer. In winter it apparently departs (no doubt 

 for warmer seas), and it is during its southward journey throughout autumn and 

 up to the end of November that mackerel sharks are commonest in the Woods 

 Hole region, while at Nantucket they (or the next species) are commonest in spring 

 when they are taken in the mackerel drift nets. As yet our knowledge of the 

 migrations of this shark into and out of the Gulf of Maine is of the haziest. Certainly, 

 however, it visits us in greater or less number annually, and is most numerous when 

 mackerel are plentiful. 



Habits. — The whole mackerel-shark tribe, as contrasted with the ground 

 sharks, are strong, active swimmers, leading a pelagic life near the surface of the 

 high seas, wandering about over the ocean in pursuit of the fishes on which they 

 prey, and often uniting in small companies, though they 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. Again and again we have sailed up on sharks 

 probably of this species, only to see them sound, just out of harpoon range, plainly 

 visible at first but soon fading from sight as they swim downward with undulating 

 motion. This is a viviparous species. In the Gulf of Maine gravid females, each 

 carrying a pair of young, have been taken in winter. 28 



» Kendall, 1914, p. 186. 



