22 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



Food. — In the Gulf of Maine the porbeagle feeds 

 chiefly on mackerel and on the herring tribe; on 

 butterfish; on ground fish, as cod, hake, cusk, 

 rosefish, flounders, or other kinds available; and 

 on squid. It has also the annoying custom of 

 foraging on the cod and other fish that have been 

 hooked on long lines and biting off the snoods. 

 It is also known to prey on the spiny dogfish in 

 the eastern Atlantic; probably in the Gulf of 

 Maine also. But we find no record of its eating 

 crustaceans of any kind. 



Breeding. — The mackerel shark tribe are ovovi- 

 viparous; that is, the eggs are hatched within the 

 maternal oviducts, but there is no placental con- 

 nection between mother and young. The embryos, 

 like those of the sand shark (p. 19), are nourished 

 chiefly by swallowing the unfertilized eggs that 

 lie nearby in the "uterus," and their stomachs 

 become enormously swollen by the masses of yolk 

 that are eaten in this way. Another interesting 

 feature of the porbeagle embryo is that the upper 

 lobe of its caudal fin is much longer at first than 

 the lower lobe, the latter increasing in relative 

 length with growth. The embryos also are very 

 large at birth; young of 18, 19, and 24 inches have, 

 for example, been found in a five-foot mother. 

 Corresponding to their large size, gravid females 

 contain only one to four young (0-2 in each 

 oviduct) . 



General range. — Continental waters in both sides 

 of the North Atlantic; southern Scandinavia, 

 Orkneys and North Sea southward to the Mediter- 

 ranean and northwest Africa in the east; northern 

 coast of Newfoundland, 33 Newfoundland Banks 

 and Gulf of St. Lawrence to New Jersey and per- 

 haps to South Carolina in the west; represented 

 in the northwest Pacific and in Australian-New 

 Zealand waters by forms that are closely allied to 

 it, but not identical. 



Occurrence in the Gulf of Maine. — It has been 

 known from the days of the earliest settlement 

 that stout-shouldered, surface-swimming sharks 

 of moderate size, with "mackerel" tails and slen- 

 der, smooth-edged teeth are tolerably common in 

 the Gulf of Maine; they are universally referred to 

 by the fishing popidation as "mackerel sharks." 

 During the first half of the last century only one 

 such shark species was recognized in our waters. 

 And while more recent researches have proved 



" One reported at Raleigh, on the Newfoundland side of the Strait of 

 Belle Isle, July 1929, by Dr. W. Q. Jeffers. 



that two actually occur within the limits of the 

 Gulf (this and the next described) the present 

 species is the more northerly of the pair, and 

 much the more frequently taken in the Gulf. 

 Hence it is probable that most of the mackerel 

 sharks that fishermen often see swimming lazily 

 on the surface, and often catch, off the shores of 

 northern New England, belong here. 



Seemingly, the chief centers of population for 

 the porbeagle in the western Atlantic are along 

 outer Nova Scotia, and in the western side of the 

 Gulf of Maine. Thus, while there are but two 

 published records for it from the Newfoundland 

 Banks, and one (besides verbal reports) in the 

 Gulf of St. Lawrence, fishermen report it as the 

 commonest large shark along the Atlantic coast 

 of Nova Scotia. Apparently it tends to shun the 

 cold waters of the Bay of Fundy, for it is recorded 

 only twice from Passamaquoddy Bay, one in 

 August 1900, the other on October 3, 1935. 34 But 

 it is so plentiful farther west in the Gulf that inci- 

 dental catches are on record of 19 that were taken 

 in one night by six men on hand lines, and of about 

 150 taken by one crew during three weeks' cod 

 fishing near Monhegan Island, Maine. We have 

 ourselves hooked or sighted about one per three 

 or four days' fishing, on the cod grounds in general 

 in the western side of the Gulf, the majority near 

 Platts Bank off Cape Elizabeth, but some also on 

 Nantucket Shoals. 35 Certainly it is the most often 

 seen of the larger sharks around the Isles of Shoals 

 and near Cape Ann, and it has been characterized 

 repeatedly as "common" in Massachusetts Bay. 36 



To the westward the porbeagle is described as 

 not uncommon near Woods Hole (we have not 

 seen it there). We saw a small one about 3 feet 

 long taken in an otter trawl at 60 fathoms, off 

 Marthas Vineyard, on February 20, 1950, by the 

 Eugene H; and it has been reported on several 

 occasions from Rhode Island waters. But it ap- 

 pears only as a stray off New York and to the 

 southward. 



Thus, the latitudinal range within which it 

 occurs regularly off the American coast covers 

 only something like 5°. And its on- and offshore 

 range is correspondingly so narrow that no report 



» Reported by McGonigle and Smith, Proc. Nova Scotia Inst. Sci., vol. 

 19, 1936, p. 180. 



85 Cod tagging cruises of the IT . S. Bureau of Fisheries. 



18 Actually no sharks other than the spiny dogfish (p. 47) are "common" 

 In the Gulf of Maine, In the sense that this term is applied to such fish as 

 herring, cod, mackerel, and other species, but only as relative to other sharks 

 of corresponding sizes. 



