BIGELOW: COAST WATER EXPLORATION OF 1913. 263 



and there is no actual hydrographic evidence that abyssal water enters 

 at all into the Gulf. Between Cape Cod and New York, the chief 

 components of the coast water are the surface and upper layers of the 

 Gulf Stream, which is far more important here than in the Gulf of 

 Maine, and river water, northern water being hardly appreciable, 

 except perhaps in exceptional years (p. 266). Salinities and tempera- 

 tures do not afford any actual indication of upwelling here in summer 

 (p. 260) . South of New York the problem of upwelling assumes more 

 importance, because of the prevailing direction of the winter winds; 

 though no evidence of it was found in summer. But the questions to 

 what degree it is effective in winter and whether it floods the shelf, 

 or is limited to the waters outside the slope can not yet be answered. 



Oceanography of the Gulf of Maine and of the North Sea. 



A brief comparison between the Gulf of Maine and the North Sea 

 is pertinent because the latter is now the best known water-area, both 

 physically and for its plankton, on the globe. (For an excellent 

 summary of the hydrography of the North Sea, see Knudsen, 1909). 

 Both also support fisheries, which differ more in extent than in kind. 



The salinity of the North Sea as a whole, 34%o to 35%o, is considera- 

 bly higher than that of our Gulf. At the west end of the English 

 Channel, and off the north coast of Scotland, the two sources from 

 which ocean water enter, it is above 35%o. On the other hand, there 

 is a coast-belt fresher than 34%o, near Denmark; and of course the 

 surface grows much fresher passing through the Skagerrak into the 

 Baltic. The salinity of the North Sea further differs everj^'here 

 from that of our Gulf in being practically uniform from surface to 

 bottom, the result of strong currents; and in changing very little from 

 season to season. 



The Gulf of Maine agrees very closely in mean surface temperature 

 (about 48°) with the central parts of the North Sea (48.2°); and 

 Massachusetts Bay (50°-52°) corresponds with its southern part 

 (50°). This generalization can be extended also to the upper ten 

 fathoms of the whole of the North Sea, and to the whole column 

 of water (about twenty fathoms) in its southern half. The coldest 

 winter temperature of the North Sea ranges from 37.4° near Den- 

 mark to 42° near Scotland — in the central part it is 39°-40°; which 

 is slightly warmer than the Gulf of Maine, where the winter temper- 

 ature as a whole is about 36°-37°. On the other hand the North 



