142 BULLETIN OF THE BUREAU OF FISHERIES. 



Breed iiK/ h<(hlts. — The Tahoe trout, or pogy, ascends the streams to spawn and 

 beoins spawnint;-, usually, about the middle of April. Mr. E. W. Hunt stated that 

 the troul heoan spawning about two weeks later than usual in lOO-i, and that they 

 averaged somewhat smaller in size than in former j-ears. He also stated that the 

 average number of eggs obtained from each female was about 1,400. As late as August 

 a few trout may be found spawning in some of the streams, but generally the vast 

 majority arc through by the middle of June. 



Some years ago the ('aliforuia Fish Commission established two good hatcheries on 

 Lake Tahoe. Each hatchery has a capacity of al)out a million eggs, and almost every 

 season both are tilled to their utmost capacity with the eggs of the Tahoe trout. The 

 fry developed from these eggs are planted in Lake Tahoe itself and in the small lakes 

 tributary to it. Many of these small lakes did not possess trout until they were 

 stocked by the commission. The fry are usually planted about the tirst week in 

 August. The large increase in the catches of trout during the past two seasons is 

 undoubtedly due to two factors, tirst the activity* of the California Fish Conunissiou in 

 keeping the lake well stocked, and second, for the past four years the beginning of 

 the open season on June 1 instead of May 1 as formerly, so that the trout are now 

 protei'ted during the most important part of their spawning season. 



The silver trout spawns in the lake, hence its eggs can not be obtained for the 

 hatcheries. 



Food. — Owing to the fact that the tishcrmen kept their trout alive several hours 

 after catching them, if was diiEcult to obtain good material for a study of the food. 

 As a result, out of a dozen stomachs of Tahoe trout that wei'c examined, only three 

 were found to contain material of any conse(iucnce. The other nine contained only 

 small quantities of insect fragments that were too small to identify. Two stomachs 

 from trout that were 1<! inches long were about one-fourth full. Each contained from 

 .50 to 75 Ddplnihi and fragments of adult ChiroiKintKs and chironomid pupa'. The 

 third stomach, from a male 15 inches long, contained 4.*i cubic centimeters of Daph- 

 )ii<(, a small fi'agmcnt of a beetle, and a few small fragments of other insects. The 

 iuind)er of individuals making up the 4.0 cul)ic centimeters of Daplinin was estimated. 

 Two separate measurements were made by allowing the material to settle for 24 hours 

 in graduated cylinders. In one case, 1.1 cubic centimeters contained 430 J)(ipJin!a., 

 and in the other, L 3 cubic centimeters contained 477 individuals. The average for 

 these two measurements is 378 individuals per cubic centimeter, which multiplied by 

 4.6 gives a total of 1,739 Daphnia. This, however, does not repres(»nt the total 

 destructitm o'i Ihi/i/miit for this single meal, as the Ijrood chambers of a large numl)er 

 of them contained either eggs or embryos. About two-thirds of the individuals were 

 Dtip/i/i/(/ jii/le.r and the refit were I). /i//i>h'?iii. It is an interesting fact also that no 

 Cop(»poda were eaten, since both Epl><ch\n'(t and D/'apfomus were nuich more abundant 

 than Ddjilniia. The former are much more powerful swimmers than the latter, but 

 this fact alone is scarcely sufficient to account for their entire absence from the menu 

 of the trout. A difference in size does not answer the question, for Ejiixchiim iiera- 

 denxtx is a large form and could be obtained as easily, apparently, so far as size is con- 

 cerned, as Dnphiiia. The three trout that had eaten Ditj>hnla must have obtained 

 them at a depth of at least 40 feet, for these crustac-eans were not found any nearer the 

 surface than this in the davtime on the feeding ground where these tish wei"e caught. 



