722 



BULLETIN OF THE BUKEAU OF FISHERIES 



in spite of the very considerable area covered by the stations and the variation in 

 depth from 50 to 90 meters. 



The contrast between this low bottom salinity on Georges Bank and the more 

 saline water that then bathed Browns Bank (33.02 per mille) has already been 

 comnsated on (p. 719). 



It is probable that wide regional variations in bottom salinity would have been 

 recorded all along the shores of the gulf in March at depths less than 20 to 30 

 meters, corresponding both to the precise depth and to the location relative to the 

 sources of land drainage, had more readings been taken so shoal, because the values 

 ranged from 32.3 to 33.1 per mille at the bottom of Massachusetts Bay at depths 

 of 12 to 70 meters on February 24 to 28, 1925, and from 32.4 to 33 per mille at 25 to 76 

 meters on March 10 of that year, the higher values at the deeper stations, the lower 

 values at the shoaler stations. In the Ipswich Bay region, however, between Cape 

 Ana and the Isles of Shoals, the bottom water varied only from 32.9 to 33.2 per 

 mille in depths of 39 to 64 meters on March 12, 1925 {Fish Hawk cruise 9). 



ANNUAL VARIATIONS IN SALINITY IN MARCH 



An approximate idea of the variation in salinity that may be expected from 

 year to year in the gulf at the beginning of March results from the following com- 

 parison between the observations taken in its western side by the Albatross in 1920 

 and at nearby locations by the Halcyon in 1921: 



'Approiimately. 



These tables show salinities averaging about 0.4 per mille higher in 1921 than in 

 1920, at depths less than 150 meters along the coastal zone from the mouth of Massa- 

 chusetts Bay to the neighborhood of Cape Elizabeth; but the readings for the two 



