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REPORT OF COMMISSIONER OF FISH AND FISHERIES. 107 
Oyster investigations, San Francisco Bay.—Investigations having for 
their object to determine if the waters of San Francisco Bay are suit- 
able for the breeding of the Atlantic coast oyster (Ostrea virginica) 
have been conducted by Mr. Charles H. Townsend, naturalist of the 
steamer Albatross, during such periods as that steamer has been de- 
tained at San Francisco or Mare Island. These inquiries 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 attachment and growth of spat derived 
from the planted beds. The results are very gratifying, and, while not 
conclusive 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 species has thereby been constantly maintained in the 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 
supposed 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 with the eastern coast, that the water temperature 
in at least the southern part of San Francisco Bay is sufficiently high 
to fulfill all the necessary requirements of reproduction. Any failure 
to produce 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 propagation, 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 offshore into the deeper water. Here wild oysters 
of the Atlantic coast type may be found during the low tides which 
expose the outer portions of the shell banks. They are numerous, and 
when the tide is sufficiently low it is possible to gather them by hand, 
ranging in size from yearlings to specimens several years old. Consid- 
erable quantities are obtained annually in this region, and also on other_ 
