330 REPORT OF THE COMMISSIONER OF FISHERIES. 



southward so far that a fresh-water passage eould easily be traced 

 through a succession of small ponds between it and Madera Creek. 

 Short]}' afterwards suckers ( Catostom us occidentalls) appeared in the 

 latter creek, where they had not previously been seen, although the 

 stream had been under observation for eight years. " 



Not only is it apparent that the streams flowing into San Francisco 

 Bay are intimately connected, but it is also probable that the basin 

 as such is really a part of the great Sacramento-San Joaquin system. 

 The onh' channel for conununication with the latter is through the 

 salt waters of San Pablo and Suisun ba3\s. But conditions obtaining 

 in this passage are greatly modified during periods of exceptional 

 rainfall, when the drainage water from a large part of the state flows 

 through it. It is possible that at such a time the salt-water barrier 

 of the bays, though generally efi^ective, may be broken down and an 

 opportunity offered for the extensive migration of f resh-w^ater fishes. 

 Aj'res^ has shown that such migrations actually occur. He records 

 several fresh-water species as having been taken in various parts of 

 the bay of San Francisco during the unusual floods of 1862. He also 

 adds that snakes, even, were cast up alive on the beach. 



Thirteen species of fishes have been collected from the streams tribu- 

 tary to San Francisco Bay. All are identical with forms found in the 

 Sacramento and San Joaquin rivers, a careful comparison of specimens 

 from the two basins having revealed no structual difi^erences whatever. 

 Four of these species, belonging respectively to the genera Entosphe- 

 nys, Salmo, Gasterosteus, and Cottus^ are able to withstand salt water 

 and m.ay frequently pass out into the bay. The others are apparently 

 able at certain times to pass between neighboring streams, and occa- 

 sionally to take advantag'e of an open channel for migration between 

 this basin and the Sacramento. 



The relation existing between species found in this basin and that 

 of the Pajaro River to the southward remains to be discovered. The 

 results of an examination of the coastwise creeks to the north of 

 Monterey Bay will also be of great interest. 



rt Madera Creek occasionally becomes so reduced in size during the dry season that its water might 

 be held in a few barrels and its entire ichthic fanna easily placed in a pint cup. The presence of a 

 species in such a stream could hardly escape an interested observer. 



6 Ayres, Dr. W. 0., Proceedings California Academy Natural Sciences, Vol. II, p. 163. (Feb. 3, 1862.) 

 " For the last two months the fishermen who supply the markets of this city with iish have taken in 

 the bay of San Francisco many fresh-water fishes, of species generally found in the rivers, not those 

 inhabiting the smaller creeks. These have been caught at all the various points of the bay at which 

 salt-water fishes only have previously been found. It is well known that the surface waters of the 

 bay have been nearly fresh during these floods, and the fishes in question must have followed down 

 and lived this length of time in the fresh surface water. They have not been seen in the bay before 

 this. The foUowiiig species have been noticed: 



Archoplites interruptus. Algansea formosa. 



Catostomus occidentalis. Lavinia compressa. 



Catostomus labiatus. Ptychocheilus grandis. 



Orthodon microlepidotus. Mylopharodon robustus." 



Mr. Charles A. Vogelsang, chief deputy California Fish Commission, under date Jan. 24, 1905, 

 writes: "There is no question but that at this season of the year suckers, catfish, carp, and black bass 

 can be found in the waters of the bay on the Berkeley shore and on the east side of Angel Island." 



