The Rise And Decline Of The Ol^mpia Oyster 



the late Dr. A. E. Hopkins, an outstanding service to the 

 southern oyster industry which climaxed the contribu- 

 tions of one of the world's foremost oyster scientists." 



Space will not permit a review in detail of this report. 

 It is fully supplemented and illustrated by pictures and 

 graphs. Anyone interested in the detail of the work, can 

 secure a copy from the Superintendent of Documents 

 Washington, D. C. But I feel that it has such basic value 

 and interest to those who may read this article that I 

 should copy from it the following findings: 



1. Grounds on which Olympia Oysters are grown are 

 surrounded by dikes to retain a few inches of water 

 over the oysters at low tide. The maximum range of tide 

 at this place is about 20 feet, the average about 14 feet, 

 and most grounds are located between the minus 2 foot 

 and plus 4 foot tide levels. 



2. Average water temperature varies between a win- 

 ter low of 6 to 9 degrees C. and a summer high of 18 to 

 20 degrees C. In summer the temperature is highest when 

 the tide is low, and the shallow water often reaches 30 

 degrees C. while during winter low tides occur at night 

 and a temperature as low as about -2 degrees C. has been 

 recorded. 



3. Salinity of the water on the oyster beds at high tide 

 varies, in Oyster Bay, between about 26 p.p.m. in winter 

 and about 29 p.p.m. in summer; in Mud Bay the range is 

 about 27 to 29.5 p.p.m. Salinity of the surface water, how- 

 ever, is subject to greater variation. 



4. Hydrogen-ion concentration varies throughout the 

 year from a pH of 7.7 to 7.8 in midwinter to about 8.4 in 

 late spring. It is probable that prolific growth of algae in 



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