704 
BULLETIN OE THE BUREAU OF FISHERIES 
shores of Nova Scotia ( < 32.2 per mille) is thus shown to be of local origin — i. e., merely 
a part of the generally low salinity of the coastwise belt, resulting from the drainage of 
fresh water from the sundry streams that empty along that sector of the coast line. 
At the time of our spring cruise in 1920 the surface water over the eastern half 
of Georges Bank and in the southeastern part of the basin of the gulf was more saline 
than 32.5 per mille, this area of high salinity indenting Y-like into the inner parts of 
the gulf, with its one arm extending northward along the eastern side of the basin to 
the mouth of the Bay of Fundy and the other westward toward Cape Cod in a man- 
ner better shown on the chart (fig. 91) than verbally. It is probable that this contrast 
in salinity between the western and eastern ends of Georges Bank is characteristic of 
this season of the year. 
The distribution of salinity on Georges and Browns Banks also makes it proba- 
ble that the saltest surface water in the Eastern Channel and in the neighboring part 
of the basin of the gulf then took the form of an isolated pool entirely cut off from 
the still more saline surface water (>33 per mille) of the Atlantic basin outside the 
edge of the continent, reflecting some local stirring or upwelling of the water. 
Apparently it would not have been necessary to run out more than about 25 to 
30 miles from the continental edge of Georges Bank in February and March to have 
encountered surface salinities of 33 per mille and upward; but the low value (32.16 
per mille) at our outermost station on the Shelburne profile (station 20077) suggests 
that the isohaline for 33 per mille then departed farther and farther from the conti- 
nental slope, passing eastward from Georges Bank, to leave a widening wedge of less 
saline water next the edge of the continent. 
The most spectacular event in the yearly cycle of salinity of the Gulf of Maine 
is the sudden freshening of the surface near its shores, which follows the spring 
freshets of its rivers, an event happening earlier or later, according to the date when 
the snow that blankets New England, New Brunswick, and Nova Scotia melts and 
the ice in the lakes and streams goes out. In this respect the spring of 1920 was 
late, following a severe winter. The effect of this outpouring of land water makes 
itself evident, by lowered salinity at the surface, earlier off some parts of the coast 
than off others. However, this regional variation does not correspond directly to 
the latitude of the rivers concerned, because the effect of the Kennebec was made 
evident in 1920 by surface salinity nearly 1 per mille lower close in to its mouth 
(station 20058) than either to the westward or to the eastward of it as early as 
March 4 (fig. 91); but any effect that the discharge from the Merrimac may have 
had on the preexisting salinity up to that date must have been confined to the 
immediate vicinity of its mouth, because the surface was then about the same for 
the general sector between Cape Elizabeth and Cape Ann as for the offing of the 
river (32.2 to 32.3 per mille). 
In 1925 (an earlier spring on land as well as in the sea) fresh water from the 
Merrimac had developed a streak of low surface salinity (30.7 per mille) for about 6 
miles out from the mouth of the river by March 12, with slightly higher surface 
values (31 to 32 per mille) to the north and south ( Fish Hawk stations 20 and 28, 
cruise 9, pp. 1009, 1010). While higher values in Massachusetts Bay (32.4 to 32.9 per 
mille; Fish Hawk cruise 8, March 10, stations 2 to 18A; p. 1004) prove that low salin- 
ities from this source had not yet spread southward past Cape Ann, the freshets from 
