TEE SACRAMENTO SALMON. 207 



the parent fishes spawned — the 5,000 mentioned in the experiment 

 were from eggs taken in California — but because their ocean feeding 

 grounds are not far off-shore, and in their two years' residence in the 

 ocean they have not wandered far from the point at which they entered 

 it. When it comes time to return to fresh water, their native stream 

 is the first to attract attention. 



Adult salmon may be found in the Sacramento Eiver at any time 

 of year. There are, however, two distinct runs, the earlier of which 

 passes iip the river during April, May and June, and the later during 

 August and September. The former is known as the spring run and 

 the latter as the fall run. The salmon of the spring run ascend the 

 river to the headwaters, such as the upper Sacramento, McCloud 

 Eiver and Hat Creek, and some of the earlier ones even pass Pit Eiver 

 Falls and enter Fall Eiver. The salmon of this run spawn mainly in 

 August. The fall salmon do not ascend the river so far as those of 

 the spring run, but turn aside into the lower tributaries, or spawn in 

 the main river. They reach their spawning grounds during the latter 

 half of October, November, and the first half of December. The main 

 river is very low at this time of year and only a small portion enter the 

 tributaries. 



Details of Migration. 



When the salmon enter the bay from the ocean, they come in against 

 the ebb-tide. They stem the current till the tide changes, and then 

 run out against the flood-tide, losing much of the distance gained 

 during the ebb. That they do not lose altogether as much as they 

 gain may be understood from the following explanation : 



The tide runs up the bay and river as a broad low wave, on the 

 upper side of which is flood-tide, and on the lower side ebb-tide. This 

 wave is about three hours going from San Francisco to Benicia; it 

 reaches Collinsville in about four hours, and Eio Vista in four and a 

 half hours. When the crest of a wave is at Isleton, its trough is about 

 at the Golden Gate. The farther the tide extends up stream, the 

 smaller the wave, the shorter the flood, and (as the flood and ebb must 

 together equal' twelve hours) the longer the ebb. The following diagram 

 will illustrate the movements of a salmon in passing through the bays: 

 a, b and c represent the tide-wave at successive points as it passes 

 up the bay. -<-3 indicates ebb-tide, and s->- flood-tide. Suppose that a 

 salmon enters the Golden Gate, G G, at the beginning of ebb-tide, 



