REPORT OF COMMmSIONER OF FISH AND FISHERIES. 107 



Oi/ster investigations, ^San Francisco Bay. — Investigations liaviug for 

 their object to deteniiiiie if the waters of Sau Francisco Bay are suit- 

 able for the breeding- of the Athmtic coast oyster ( Ostrea virf/inica) 

 have been conducted by Mr. Charles H. Townsen<l, naturalist of the 

 steamer Albatross, during such periods as that steamer has been de- 

 tained at San Francisco or Mare Island. These in(j[uiries have been 

 carried to all parts of the main bay and to San Pablo Bay, and have 

 had reference to the temperature and density of the water, the character 

 of the bottom, and the actual atta<3liment and growth of spat derived 

 from the planted beds. The results are very gratifying, and, while not 

 couclusive on all points, they seem to indicate that the conditions 

 existing in some portions of the bay are not unfavorable to the estab- 

 lishment of self-sustaining colonies of the eastern oyster. 



The oyster industry of the Pacific coast, exclusive of the trade in the 

 small indigenous species, has never extended beyond San Francisco 

 Bay, where it is restricted to the growing or fattening of seed or year- 

 ling oysters, brought annually in large quantities from the Atlantic 

 coast. This method of transplanting oysters has been practiced ever 

 since the completion of the first overland railroad, and a supply of the 

 eastern sjiecies has thereby been constantly maintained in tlie waters 

 of San Francisco Bay, yet it has generally been understood that no 

 natural increase has taken place in this region. To account for this 

 sup loosed failure to propagate, it has been assumed that the tempera- 

 ture of the water during the breeding season is lower than it should 

 be, but the subject has never been investigated and practically nothing 

 has been known regarding it. 



While the observations of Mr. Townsend were limited to a few 

 months in each year, temperature data covering all seasons have been 

 obtained from other sources, and these lead to the conclusion, based 

 upon a comparison witli the eastern coast, that the water temperature 

 in at least the southern part of San Francisco Bay is sufficiently high 

 to fuliill all the necessary requirements of reproduction. Any failure 

 to x^i'oduce spat would therefore have to be traced to other causes; but, 

 as a matter of fact, Mr. Townsend finds that the Ostrea virginica does 

 breed in this region and that the young attaches itself under suitable 

 conditions. To what extent this prevails, however, can only be deter- 

 mined after a more complete study of the bottom. The largest and 

 most important tract of oyster i^ropagation, according to Mr. Town- 

 send, is the region of the natural shell banks of native oysters along 

 the east side of the bay, beginning at Bay Farm Island and extending 

 well southward and off'sliore into the deeper water. Here wild oysters 

 of the Atlantic coast type may be found during the low tides which 

 exi^ose the outer portions of tlie sliell banks. They are numerous, and 

 when tlie tide is sufficiently low it is possible to gather tliem l)y hand, 

 ranging in size from yearlings to specimens several years old. Consid- 

 erable quantities are obtained annually in this region, and also on other 



