804 



BULLETIN' OF THE BUKEAU OF FISHEKIES 



SALINITY IN MIDWINTER 



The general oceaiiographic survey of the inner part of the gulf carried out by the 

 Halcyon during the last days of December and first half of January, 1920-21, affords 

 our only picture of the salinity of the offshore waters for that season. 



These midwinter observations prove interesting from several view points. In 

 the first place, when added to the winter records for Massachusetts Bay and for the 

 Bay of Fundy for other years they show that little alteration takes place in salinity 

 from autumn to midwinter, evidence that this season sees no extensive indraft of 

 the saline slope water over the bottom. The regional distribution of salinity in the 

 upper 100 meters gives evidence to this same effect, for this was highest near shore 



Fig. 163.— Salinity at the surface, December 29 1920, to January 9, 1921. Contours tor every 0.2 per mille 



in the western side of the gulf as in May instead of in the eastern, as is the rule 

 at other times of year. This distribution appears most clearly on the sui'face pro- 

 jection (fig. 163), with 32.7 per mille off Cape Ann but only 32.5 per mUle in the 

 Nova Scotian side of the basin; likewise at 40 meters and at 100 meters, where these 

 same localities were the most saline. These, in fact, were the only stations where 

 the 100-meter salinity was then higher than 33 per mille, so that this isohaline 

 paralleled the northern and western slopes of the. gulf at this level. 



The bottom water of the two sides of the basin at 200 meters and deeper then 

 proved almost precisely alike in the two sides of the basin (about 33.9 per mille off 



