MIGRATIONS OF COD 
85 
Given favorable currents, any area in the Gulf of Maine is thus a potential source 
of supply for any cod ground there; hence for Nantucket Shoals the question of the 
circulation of the water is the crucial one in this connection. More specifically, 
whether or not Nantucket Shoals is particularly favored with cod fry depends upon 
whether the nontidal drift flows toward that region from important spawning grounds 
far enough away for the eggs and larvae to develop into bottom-dwelling fry by the 
time they reach the shoals. 
For determining the general circulation of the ocean off the New England coast 
numerous drift-bottle and current-meter experiments have been made by Bigelow 
and others. The drift-bottle experiments at best can give but a rough picture of 
the circulation of the upper stratum. Conditions may change from day to day, so 
that an average result, covering perhaps one to two months of time, is all that can 
be obtained as to routes and velocities between the setting out and recovery of the 
bottles. However, it is almost certain that part of the drifting cod eggs, larvae, and 
to some extent the fry, follow the same route as the bottles. Up to the present the 
experiments made with these latter furnish our most dependable means of tracing 
the destiny, in a general way, of the cod spawn discharged in any particular part 
of the Gulf of Maine. 
Bigelow (1927, p. 972) found that the Gulf of Maine is dominated by an anti- 
clockwise nontidal circulation, differing in velocity and in detail with the season. 
A rough picture of the circulation in July and August is given in Figure 26. As the 
currents from offshore do not pass over the cod grounds south of Cape Cod, except 
possibly by a long and tortuous course, they are not treated here. To the westward 
of Nantucket, although little is known of the conditions existing in winter, the fact 
that Bigelow found a shore drift to the Rhode Island-North Carolina region in sum- 
mer, carrying flotsam away from the shoals, suggests that this region does not con- 
stitute a prolific source for Nantucky Shoals fry. A large number of cod spawn in 
this westward region, so that a study of its hydrography presents an important 
problem for the future. 
The dominant drift in the Gulf of Maine, which sets in a southwesterly direction 
along the coast of Maine, veers to the eastward well off Cape Cod, and thence toward 
Nova Scotia, but part of it follows the coast southward past Cape Cod and down to 
Nantucket Shoals. It is this part of the drift that is of most importance in bringing 
to Nantucket Shoals pelagic cod fry originating from eggs spawned to the north- 
ward of Cape Cod. 
In late winter and early spring the northeast-southwest drift along the coast of 
Maine and southward past Cape Cod is most definite and reaches its greatest velocity 
of the year. Bigelow (ibid., p. 975) states that “under these circumstances flotsam 
of any kind (buoyant fish eggs, for instance, or the larvte hatched therefrom) that 
may drift from the north into the northern side of Massachusetts Bay or that may be 
produced there tends to drift out of its southern side.” This being so, we have 
favorable conditions for the drift of cod fry to Nantucket Shoals from regions north 
of Cape Cod, providing that the velocity of drift is such that the resultant fry will 
reach the southern Massachusetts region at a time when they are seeking the bottom. 
With regard to the velocity of the dominant nontidal drift in the Gulf of Maine 
in so far as it affects the destiny of cod fry, the year fails into two periods — a winter 
season from October to May, when prevailing northwesterly winds enhance the 
speed of the current along the shores of Maine and Massachusetts and hold it close 
