470 



BULLETIN OF THE BUEEATJ OF FISHERIES 



surface and bottom samples taken at each station on July 15, 1925, between 3 and 

 4 p. m., when the tide was one-third flood. The greatest number of salinity deter- 

 minations was made at harbor Station No. 2 and at the inshore Sound Station No. 6 

 at various stages of the tide. The monthly averages at these Stations for July and 

 August of both years are shown in the following table. 



Table 9. — Salinity of the water 



Harbor station No. 2. 



Tip 



Do 



Do — 



Sound station No. 6. 



Do 



Do 



Do 



Month 



July.... 

 August. 

 July.... 

 August. 

 July.... 

 August. 

 July.... 

 August. 



Year 



1925 

 1925 

 1926 

 1926 

 1925 

 1925 

 1926 

 1926 



Salinity per mille 



Surface Bottom 



26.32 

 26.93 

 27.17 

 27.59 

 27.91 

 28.10 

 27.70 

 28.15 



26.77 

 27.87 

 27.47 

 27.95 

 28.05 

 28.21 

 27.81 

 28.50 



The salinity is rather constant in the deeper waters of the Sound, and the varia- 

 tion from year to year is comparatively small, while in the inshore and harbor areas 

 we find noticeable changes occurrmg according to the stage and range of tide and 

 amount of river discharge. In several instances observations were made during a 

 complete tidal cycle, from low water to high water and back again. In the following 

 table the scries taken at Station No. 2 on August 24, 1925, is given and shows the 

 typical changes in water conditions that occur at various stages of the tide. This is 

 shown graphically also in Figure 26. 



Table 10. — Effect of tide on physical conditions, Station No. 2, August 24, 1925 



Since the range of tide on this particular date is but 0.2 foot above the mean 

 range, the changes in water conditions can be regarded as intermediate between 

 those that occur with extreme spring or neap tides. Changes in salinity are least 

 at the time of neap tides and greatest with the spring tides. 



The differences in sahnity between top and bottom samples were generally 

 less than 1 per mille and naturally were highest at Station No. 1, where fresh water 

 enters the harbor from the Wepawang River, and least at Station No. 6, in the 

 Sound. Occasionally, however, extreme differences were found following heavy 



