520 U. S. BUREAU OF FISHERIES 



ington on the problems of the Olympia oyster industry. The Wash- 

 ington State Department of Fisheries and Game constructed an 

 adequate field laboratory at Olympia, purchased a boat, and pro- 

 vided a boatman as well as some of the operating expenses. The 

 investigation is being directed by Doctor Hopkins of the bureau, 

 and it is planned to continue the work for several years. 



The primary purpose of this investigation is to develop effective 

 methods of collecting seed oysters in order to rehabilitate and expand 

 the industry. Experiments made during the summer gave highly 

 satisfactory results. The daily abundance of spat obtained in the 

 two most important oyster-producing bays was determined through- 

 out the season and at the same time records of temperature, salinity, 

 pH, and plankton were kept. In Oyster Bay setting took place in 

 two distinct periods, centering, respectively, in June and August. 

 In Mud Bay only one important setting period occurred during June 

 and July. A comparative study is being made of hydrographical 

 conditions in these two apparently almost identical neighboring bays 

 in order to throw light on the causes of these differences and on the 

 factors favorable to setting of oyster larvae. 



The hermaphroditic Olympia oyster carries its larvae for some 

 time in the mantle chamber. Counts of larvae shoAved that an in- 

 dividual may bear up to 350,000 at once, the number depending 

 roughly on the size of the parent. Spawning began early in May 

 and some gravid specimens were found as late as the middle of 

 November, though spawning was most general and profuse in May 

 and early June. 



Wire baskets of shells suspended from floats in the deep channels 

 well removed from the main oyster beds obtained a set considerably 

 greater than that on the best seed grounds. Few soat were caught 

 in the surface few inches of water ; the maximum number were taken 

 at a depth of 10 to 20 inches, below which the abundance gradually 

 diminished to a depth of 8I/2 feet, the greatest depth tested. 



A modification of the egg-crate filler has been developed as a spat 

 collector for use in the dikes in which Olympia oysters are produced. 

 The new type presents a large amount of horizontal surface, absent 

 in the case of the standard filler, and permits circulation of water 

 through the cells. Most spat were caught on the under horizontal 

 surfaces, few on the upper. Because of the free circulation of the 

 water, the vertical surfaces caught more spat than similar surfaces 

 on the standard filler. Although the new type consists of one-fourth 

 less paper, it caught three times as many spat as the standard. 



Investigations in Oregon and California. — During the past year 

 experiments have been conducted by H. C. McMillin in Oregon and 

 California on native, eastern, and Japanese oysters. There is a 

 widespread interest in oyster culture in these States, bvit a large 

 majority of the persons now engaged in the industry have had no 

 practical experience. For methods of culture and harvesting they 

 rely almost solely on printed matter, written or verbal suggestions, 

 and demonstrations with seed, or young oysters, on various portions 

 of their lands. Because of this some time has been spent on projects 

 intended to illustrate the rudiments of oyster culture to the growers. 



A survey of oyster bottoms in Yaquina Bay revealed that this area 

 contains about 200 acres of natural beds, all of which occur below 



