FISHES OF THE GULF OF MAINE 



23 



of it has come to hand from Georges or Browns 

 Banks, only one from the Nova Scotia slope off 

 Sable Island, and two from the Grand Banks, as 

 just noted. On the other hand, few come in-shore 

 close enough to be picked up in pound nets or 

 weirs. 



All published records of mackerel sharks from 

 the Gulf, and all that we have seen there, have 

 been in the warm half of the year, and something 

 like 70 percent of the landings of porbeagles on 

 the coast of Maine are for August to November. 

 But its presence in the Gulf in winter is proved 

 by our receipt of a photograph of a porbeagle 

 embryo, taken from a female caught in January, 

 off Portland, Maine, in 1927. And it is also 

 caught in winter as well as in summer in north 

 European waters. Apparently it simply descends 

 into deeper water during the winter to escape low 

 surface temperatures, feeding little, else more of 

 them would have been caught in the Gulf during 

 the winter fishery with long lines for hake (llro- 

 phycis) . 



In the Gulf of Maine, females containing em- 

 bryos have been taken in August (near Monhegan 

 Island, Maine) ; in October (off Barnstable, Mass.) ; 

 in November (off Portland, Maine) ; and in Jan- 

 uary (off Portland, Maine). But the fact that the 

 largest embryos have been found in European seas 

 in summer suggests that most of the young are 

 not born until then. 



Importance. — The liver oil of the porbeagle, 

 mixed with other fish oils, was in demand for use 

 in tanning leather during the first quarter of the 

 19th century. And it is interesting to read that 

 as much as 1 1 gallons of oil has been obtained from 

 the liver of a single shark 9 feet long. 



This demand had almost entirely died before 

 1850 and has never revived. But a new demand 

 has developed of late years for porbeagle meat, 

 which resembles swordfish in taste as well as in 

 appearance, resulting in landings for this purpose 

 of about 46,000 pounds in 1944 on the coast of 

 Maine, and of 71,600 pounds in 1945. Assuming 

 an average weight of, say, 50 pounds, this corre- 

 sponds to a commercial catch of about 900 to 1,400 

 sharks. There is no special fishery for porbeagles 

 at present in the Gulf of Maine, or for any other 

 sharks for that matter. About four-fifths of those 

 brought in are taken in gill nets set on bottom for 

 ground fish, and most of the sharks caught in this 

 way are landed in Portland, Maine. The re- 



mainder are taken by seines, traps, weirs, hook and 

 line or harpoons. And most of the porbeagles 

 taken in these ways are discarded at sea. 37 The 

 porbeagle is not "game" enough to be of any in- 

 terest to sport-anglers. 



Sharp-nosed mackerel shark Isurus oxyrinchus 

 Rafinesque 1810 



Atlantic mako 

 Bigelow and Schroeder, 1948, p. 124. 



Description. — This shark resembles the common 

 mackerel shark so closely that we need merely 

 point out the points of difference. Most obvious 

 of these is that while the first dorsal originates 

 about above the armpits of the pectorals in the 

 common mackerel shark, it stands over or behind 

 the inner corner of the pectoral in the mako, and 

 that the second dorsal originates a short distance 

 in front of the anal. The teeth, too, differ rather 

 noticeably in appearance, for while of the same 

 awl-like type, those of the mako lack the lateral 

 spurs or denticles that are characteristic of all but 

 the smallest porbeagles, and those in the front part 

 of the mouth are conspicuously flexuous in form. 

 The mako, too, is more slender bodied; its snout is 

 more narrowly conical ; its upper and lower caudal 

 lobes are more nearly equal in length; and the 

 forward part of its caudal fin lacks the secondary 

 lateral keels that are to be seen on the caudal fin 

 of the porbeagle (cf. fig. 6 with fig. 5). 



Color. — Deep blue-gray above when fresh- 

 caught, appearing cobalt or ultramarine in the 

 water, with gradual transition along the sides to 

 snow-white below; but turning dark slate gray 

 above soon after death (especially if preserved), 

 and to bluish white or pale dirty gray below and 

 on the lower surfaces of the pectorals. 



Size. — The maximum length reported for a spec- 

 imen of the Atlantic mako that was actually meas- 

 ured is about 12 feet, 38 though it has been said to 

 grow to 13 feet. The largest western Atlantic 

 specimen of which we find definite record, taken 

 off St. Petersburg, Fla., was 10 feet 6 inches long, 

 and one nearly as large (10 ft. 2 in.) was caught off 

 New York Harbor many years ago. But the com- 

 mon run caught off the middle Atlantic United 



•'See Scattergood, Copela, 1949, p. 70, for further details as to landings In 

 Maine and methods of capture. 

 ■ 3.7 meters as calculated from the size of Its jaws. 



