SPAWNING AND SETTING OF OLYMPIA OYSTERS 
443 
AIMS OF INVESTIGATION 
A great many comprehensive experimental studies have been made on the biology 
of the oyster of the Atlantic coast, Ostrea virginica, hut the only significant investiga- 
tion on the practical phases of the biology of 0. lurida was that of Stafford (1914, 
1915, 1916, 1917, and 1918). He made his observations in British Columbia, in the 
northern part of Puget Sound, where the system of oyster culture had not been 
developed to an extent comparable to that in use near Olympia. Townsend’s (1893) 
early paper gave the first general description of the industry on the Pacific coast. 
Recently Coe (1931a, 1931b, 1932a., and 1932b), Hori (1933), and Hopkins (1935, 
1936) have furnished more specific information about the species. 
The primary purpose of this investigation, which was undertaken in the spring 
of 1931 and continued through 1935, was to make an analysis of spawning activities 
and setting habits of larvae with reference to environmental conditions. By develop- 
ing such information, it was hoped that oyster growers might be assisted in the catching 
of sufficient seed oysters to restore and expand the industry. In the following pages 
the more important of the results are described. 2 
HYDROGRAPHICAL OBSERVATIONS 
The usual methods were employed for the taking and testing of water samples at 
different depths and under different tidal conditions. Specific gravity was measured 
with hydrometers certified and corrected by the National Bureau of Standards. A 
Hellige hydrogen-ion comparator was used with phenol red to determine the pH. 
Temperature of water samples was tested with standard thermometers, and in addi- 
tion, continuous records of water temperature on the oyster grounds, at the level of 
the oysters, were made with a frequently checked thermograph. 
GENERAL DESCRIPTION OF REGION 
Puget Sound is an extremely irregular, deep body of water extending roughly 
200 miles north and south in British Columbia and the State of Washington. It is 
continuous with the Pacific Ocean through the Straits of Juan de Fuca. The Sound 
is broken up into numerous bays and inlets which are generally quite deep except at 
their upper ends. Natural beds of native oysters were originally found in many of the 
small bays but were soon exhausted in all except a few localities where conditions 
necessary for successful propagation were especially favorable. 
The several bays near Olympia, Wash., have continued to produce oysters, while 
beds in other places disappeared, largely because of favorable environmental factors 
and because of the development of the system of diking the grounds and planting 
cultch employed by the growers. These bays are separated from the ocean by more 
than 150 miles of water, yet changes in salinity are relatively slight, due to the great 
depth throughout the Sound. 
2 1 wish to express my thanks to Charles R. Maybury, director of the Department of Fisheries and Game of the State of Wash- 
ington and to Charles R. Pollock, supervisor of fisheries, for their cooperation in maintaining the laboratory and supplying an as- 
sistant and boats. Since the division of commercial fisheries became an independent department in December 1932, the director, 
B. M. Brennan, has continued to support this work under trying financial conditions and he deserves much credit for what has been 
accomplished. 
It is a pleasure to express my thanks to the growers of Olympia oysters, all of whom have willingly given every possible assistance. 
I am particularly indebted to J. J. Brenner, E. G. Brenner, and D. I. Ginder, of the J. J. Brenner Oyster Co.; Ole Hanson and J. S. 
Waldrip, of the Olympia Oyster Co.; G. W. Ingham, Olympia Oyster Investment Co.; E. N. Steele; Charles Brenner; W. J. 
Waidrip; J. B. Bowman; J. H. Post; and the late Mrs. Minnie Blass. 
A large part of the credit for this work is due to H. H. Adams, who served during 5 years as a most capable and efficient field 
assistant. 
