972 BULLETIN OF THE BUEEAU OF FISHEEIES 



reproduced by the drifts of bottles that have crossed the southern side of the gulf 

 from west to east (p. 886), corroborating Huntsman's (1923a, p. 18) conclusion that the 

 dominant circulation in basins of this sort is kept in motion by the deep currents, 

 not by the movements of the surface water. The clockwise drifts, which have been 

 found to circle (or partly circle) several of the submerged banks (Georges, for 

 instance (p. 974), and Nantucket Shoals), are also equally good evidence of dominance 

 of the general circulatory scheme by the current flowing over the bottom, which the 

 banks deflect just as islands would. 



SUMMARY OF THE HORIZONTAL, NONTIDAL CIRCULATION OF THE 



GULF OF MAINE 



The nontidal circulation of the Gulf of Maine (fig. 207) is essentially estuarine 

 in type, as might have been expected from the contour of its bottom as well as from 

 the trend of its coasthne and from the large volume of fresh water discharged from 

 the rivers tributary to it. The very considerable outflow from the gulf takes place 

 at and near the surface — southward and westward past Nantucket Island and Shoals, 

 in part, but in part as a clockwise movement circhng around the eastern part of 

 Georges Bank. 



The evidence marshaled in the preceding pages — measurements with current 

 meters, drifts of bottles, temperatures, salinities, distribution of the plankton in the 

 superficial waters, and dynamics — can be harmonized with one type of dominant 

 circulation only — a general anticlockwise eddy around the basin of the gulf. 

 The demonstration of this, named by Huntsman (1924) and by me the "Maine" or 

 "Gulf of Maine" eddy, with all it implies in its biological bearing, is perhaps the 

 most interesting result of the joint explorations of the gulf. 



The circulatory features most clearly estabhshed within the gulf are as follows: 



The eddying drift is operative throughout the year but differs in velocity, and 

 generally in detail, from season to season. It is also comphcated by subsidiary eddy- 

 ing movements in the Bay of Fundy, Massachusetts Bay, Vineyard Sound, around 

 Nantucket and Nantucket Shoals, and around and over Georges Bank, which are 

 clockwise around these shoals but anticlockwise in the bays and basins, as Huntsman 

 has shown to be the rule in northeastern American waters. 



In the late summer and early autumn, when our information is the most exten- 

 sive (fig. 207), the surface stratum of the inner part of the gulf eddies anticlockwise 

 around an area of high density, the precise location of which shifts, from summer to 

 summer, from the offing of the Bay of Fundy to a center in latitude about 43° to 43° 

 30', 60 to 70 miles southerly from Mount Desert Island. 



The eastern side of the circling movement follows so definite a track northeast- 

 ward and then northward, paralleling the coast of Nova Scotia, that at least 8 per 

 cent of all the bottles yet put out in the gulf off Cape Ann and to the northward are 

 known to have followed this route, no doubt with others not reported for one reason 

 or another. The large number of bottles that have stranded on that coast shows a 

 strong tendency inshore. This Nova Scotian side of the Gulf of Maine eddy also 

 receives water in some volume from the dead zone off Cape Sable in summer, and 

 in some years a westerly drift past Cape Sable into the gulf of Maine persists from 

 spring through summer. 



