FISHES OF THE GULF OF MAINE 47 



increase rapidly in April on Georges Bank, however, and they ai< a. pest there 

 after the 1st of Ma3 T , while the last half of June, July, and August sees them at the 

 height of abundance at least on the portions of the bank resorted to by the otter 

 trawlers at that season. Whether by chance or as reflecting an actual diminution 

 in the stock of dogfish present, the catches fell off markedly during September in 

 1913, but considerable numbers were taken throughout that month. Very few were 

 actually captured by the trawlers in October, but there was a considerable increase 

 in November, probably reflecting the southward passage of the schools that had 

 spent the summer further east. A few were caught in November and December, 

 and one on the southern part of the bank (latitude about 41°, longitude about 

 67° 30') as late as January 20 to 22. Thus February is the only month when the 

 bank is entirely free of them. The time table just outlined for the year 1913 may 

 be taken as typical, for it corroborates the various reports of fishermen tabulated 

 by the Massachusetts Commissioners of Fisheries and Game in 1905. Apparently 

 dogfish reach Browns Bank rather later than they do Georges, for none were -taken 

 there on April 14 in 1913, though they are only too plentiful there in summer. It 

 is also very likely that they depart thence rather earlier, though a few lingered as 

 late as December 3 to 12 on Western Bank off Halifax in that year. Gravid females 

 have been described as arriving before the males in spring, but this remains to be 

 confirmed. 



The accompanying graph (fig. 17) of the numbers of dogs taken by certain 

 otter trawlers on Georges Bank at various dates during the year 1913 will more 

 graphically illustrate the seasonal fluctuations of this fish there, with the reservation 

 that the precise catches are governed not only by the abundance of the stock but 

 also by the precise grounds fished on and by the general success of the sets. 



The winter home of the Gulf of Maine dogfish is still to be learned. They have 

 often been said to migrate south to the Tropics, and it is certain that some dogfish 

 do reach Cuba during the cold season, but the fact that they appear so nearly simul- 

 taneously all along the coast north of North Carolina in spring, and that they leave 

 Georges Bank so late in the season, with the discovery of dogfish in deep water 

 in Long Island Sound in summer (p. 45) argues for an on-and-off rather than a long- 

 shore migration, with the deep water off the continental slope as their winter home. 

 This is corroborated by the fact that on February 20 to 21, 1920, the Albatross 

 trawled several specimens in depths of 90 and 199 fathoms along the continental 

 edge off Chincoteague, Va., and off Delaware Bay. Also, they are usually so thin 

 when they appear in spring that they can feed but little during the winter. In 

 short, evidence is gradually accumulating to the effect that the seasonal movements 

 of the spiny dogfish parallel those of the mackerel (p. 191). 



It is generally believed that dogfish not only summer more regularly in the 

 region of Massachusetts Bay now than of old, but that they are far more numer- 

 ous there than during the first half of the past century. At Woods Hole, on 

 the contrary, they and the smooth dogfish were much more plentiful before 1887 

 than at any time since then. To a certain extent, of course, reports of fluctuations 

 in abundance from year to year must be discounted as reflecting the movements 



