808 BULLETIN OF THE BUREAU OF FISHERIES 



about 0.2 per mille for the preceding six weeks. Apparently this indraft of saline 

 water from offshore then slackened, for on February 13 the water (then virtually 

 homogeneous, top to bottom) still had this same saUnity. It then salted once more 

 to 33.04 per mille on the bottom by March 4 (no change at the surf ace) , with a 

 slight further increase during the next two weeks to 33 per mille at the surface and 

 33.17 per mille on bottom, which proved the maximum for the year, succeeded by 

 the vernal freshening already described (p. 723). 



In 1925 the salinity of the deep central part of the bay remained virtually 

 unchanged from February 7'^ until March 10, at about 33 per mille, surface to 

 bottom. 



In 1921 the bottom of the basin off Cape Ann showed no appreciable alteration 

 in salinity from December and January to March, with bottom readings of 33.87 to 

 33.99 per mille at all three of these stations (10493, 10503, and 10510) in depths of 

 200 to 250 meters; but the bottom water of the bowl at the mouth of Massachusetts 

 Bay off Gloucester freshened by about 1 per mille (stations 10489 and 10511, 33.84 

 and 32.7 per mille). 



It is doubtful, therefore, whether any appreciable drift iuward over the bottom 

 of the gulf took place during the winters of 1921 or 1925; and while rising salinity 

 gave evidence of some such movement into Massachusetts Bay in the winter of 1913, 

 the alteration from month to month was so small as to prove it small in volume as 

 well as intermittent in character. In the Bay of Fundy, again, according to Mavor 

 (1923, p. 375), salinity decreased slightly between January 3 and February 28 in 

 1917.^^ In short, such evidence as is available suggests that the winter sees a 

 decided slackening of the drift of slope water inward through the Eastern Channel. 



SUMMARIES OF SALINITY FOR REPRESENTATIVE LOCALITIES 



Summaries of the annual cycle follow for localities where the greatest number of 

 observations have been taken. Unfortunately, none of these stations in the open 

 gulf afford a complete year's cycle at intervals close enough, either in time or in depth, 

 to be more than preliminary, but at the least they will serve to illustrate the major 

 changes to be expected from season to season and from the surface downward. 



BAY OF FUNDY 



Mavor's (1923) records of salinity on 18 occasions, covering the interval from 

 August 25, 1916, to May 10, 1918, at a station near the mouth of the Bay of 

 Fundy, between Grand Manan and Nova Scotia, are especially instructive in this 

 connection. The outstanding event in the annual cycle of salinity here is the sudden 

 freshening of the surface that takes place in spring (fig. 165), occasioned by the out- 

 pouring of fresh water from the rivers emptying into the bay — chiefly from the 

 St. John. Tins occurred between the 10th of April and the 10th of May in both of 

 these years (probably the usual date). As described above (p. 743), the surface then 

 salts again as the thin stratum so affected mixes with the salter water from below, 



"No salinities wero recorded prior to that date during that winter. 



" Prince station 3, Jan. 3, salinity 32.6 per mille at the surface, 33.24 per mille at 100 meters, and 33.33 per mille at 175 meters, 

 while on Feb. 28 the values at these same depths were 32.06, 32.97, and 33.01 per mille. 



