FISHES, LAHONTAN SYSTEM OF NEVADA AND NORTHEASTERN CALIFORNIA. 5 1 



spawn. Some which were dissected did not appear to be ripe. They were very shy and fled at once 

 on the approach of a shadow, the jar of crunching gravel, or a heavy footfall; but the observer could come 

 close if the move was steadily made. The passage of large numbers continued intermittently, until 

 about May 16, when it became evident that the migration was waning rapidly. After May n none was 

 seen moving upstream. 



In the meantime spawning had begun and was progressing with great activity. On April 24 the 

 first females were seen depositing eggs. However, several ripe males and females were secured a little 

 earlier. By May 5 every suitable bar or gravel bed was occupied by spawning fishes, whose activities 

 entirely ceased before the i6th. 



The spawning is entirely suckerlike; it occurs in relatively shallow water where the flow is rapid, 

 often at the head of a bar which turns or parts the current. At times the dorsal fins project above the 

 surface, and in very shallow places where there is much crowding the whole back is exposed. Two, 

 three, or even five or more males attend a single female during the spawning act. They wriggle over, 

 alongside of, and around her, thrashing the water with such violence that close observation is impos- 

 sible. Spawning fishes are easily alarmed, but if the observer approaches in the water he may occa- 

 sionally get close enough to pick up specimens without difficulty. Eggs may be stripped and fertilized 

 with ease. 



The ovaries are large, the eggs small and very abundant. No enemy appeared on the spawning beds, 

 but the habit of depositing the eggs in shallow water often exacts an enormous toll from the yotmg of 

 the species, for a sudden fall in the volume of the river may leave many nests high and dry in a 

 single day. 



No doubt the migration and spawning activities here described are fairly typical. Usually the 

 water is so high, swift, and roily that very little of what is going on beneath its surface can be seen. Of 

 late years irrigation projects and power plants have at times seriously interfered with the flow of the river 

 and consequently disturbed the normal life of some of its native species. During the winter of 1911-13 

 the snow was very light in the moimtains and there were no heavy rains. The dam at Tahoe was closed 

 early, and a large amount of water was at the same time diverted from the channel of the Truckee above 

 Derby. The lower part of the river then became so reduced that water began to flow back from Pyra- 

 mid Lake (where it was higher than usual), up the river, down the slough, and into Winnemucca Lake, 

 the surface of which is lower than that of Pyramid Lake. This flow continued until the water of the 

 channel between the lakes was practically as brackish as that of the lakes themselves. No "cui-ui " 

 appeared in the river until a full month after the usual time, and then not until high water suddenly 

 forced back the brackish flow and sent a fresh stream out into the lake. On the advent of this directing 

 current the usual rush of "cui-ui" from the lakes began; large schools passed up the river (May 17) and 

 spawned at once. During the earlier back flow sufficient depth was maintained for the easy passage of 

 the fish, but it seems probable that there being no inflow of fresh water the waiting migrants were 

 unable to find the mouth of the river. 



The time of departure of the fish from the river could not be determined because of high water, as 

 no "cui-ui" were seen at anytime going down stream. A few individuals were seen in the river June 14, 

 when the water suddenly cleared. On June 5. and for many days thereafter, large numbers of dying, 

 dead, and decaying specimens were found at the mouth of Winnemucca Slough. This mortality among 

 the "cui-ui ' ' is said to be a regular feature of the season at this place. If a similar death rate prevails in 

 the lower Truckee, it was not evident at the time. However, the river was deep, the current strong, and 

 the lake was stormy when the examination was made. A few dead individuals are always found along 

 the river after the breeding season. It is possible and quite probable that the death rate is high just 

 after the breeding season, but there is nothing to indicate that all the fish die after spawning. The dead 

 and dying examples bore no evident scars. 



Diligent inquiry brought forth no account of the species spawning in the lakes. No one was found 

 who had even seen one there. Hours of observation from tufa domes failed to detect any among the 

 myriads of fishes which could be easily identified. Yet on May 11, igi^.largenumbersof "cui-ui" were 

 found depositing eggs along the shallows near some springs on the southwest shore. Both ripe males and 

 females were examined. The Indians were after them almost immediately, and they declared that 

 these were the first that they had seen in the lake. None was observed here May 16 or later. A few 

 individuals were found spawning in Winnemucca Slough. 



During the breeding season the males differ from the females in color and there is some variation 

 in both sexes. The males have a dense black stripe 5 to 6 scales wide extending 10 scales below the 



