610 U. S. BUREAU OF FISHERIES 



under as nearly identical conditions as possible. In accordance with 

 the program outlined above the inferior lots will be discarded later 

 in the season. 



While the breeding work is still in its infancy it is already evident 

 that the results Avill be of great practical value. Probably the most 

 notable result up to the present time is the demonstration that the 

 time at which trout spawn is determined primarily by heredity, al- 

 though evidently influenced to some extent by environmental condi- 

 tions. At the Pittsf ord station there are several strains of trout from 

 different sources and these all showed marked difference in the date 

 on which they are ready to spawn. This was shown in a striking 

 manner in one pond containing two strains of brook trout. When 

 examined on October 28 practically all of the fish of one strain were 

 ready to spawn while the other strain shoAved noi indications of being 

 ripe. 



Moreover, it appears that the relative time of spawning is constant 

 from year to year. The earliest fish to spawn in 1929 were also the 

 first to spawn in 1930, In 1929 the eggs were taken on October 29 

 while in the following year the fish were ready to spawn on October 

 25. The advance in the spawning date in 1930 is in accord with the 

 general belief that older fish usuall}^ spawn somewhat earlier than 

 those spawning for the first time. 



Another indication that the spawning date is determined primarily 

 by heredity is the fact that all of the progeny of a single pair of fish 

 are usually ready to spawn at approximately the same time. This is 

 in striking contrast to the condition in mixed lots where the spawn- 

 ing period almost invariably extends over several wrecks. 



It is evident that this is a matter of considerable practical impor- 

 tance since it is possible by selection to develop a strain of fish with 

 a short spawning season which will result in a considerable saving 

 in labor. It will also be possible to develop early or late spawning 

 strains as desired. Furthermore, the eggs should be of better qual- 

 ity, since there is considerable evidence that fish which have been 

 closely confined for some time produce inferior eggs. 



Stocking exfervments. — During the summer and fall of 1930 plant- 

 ings of fingerling black-spotted trout and Montana graylings were 

 made in several streams in Vermont in order to determine if these 

 two species will thrive in eastern waters. Contrary to the general 

 belief it has been found, as pointed out in previous reports, that both 

 the black-spotted trout and the grayling do well at the Pittsford 

 hatchery so it is evident that the climatic conditions are favorable 

 for both species. The black-spotted trout occurs naturally under a 

 wide range of conditions in the West, and it is not impossible that 

 they may be found better adapted to certain eastern waters than the 

 native brook trout. 



During the past two years several hundred rainbow and steelhead 

 trout have been tagged and liberated in Vermont streams. These 

 were all adult fish which had been reared at the Pittsford station. 

 So far only a small percentage of the tags have been accounted for, 

 but enough have been returned to indicate that the fish have lived 

 up to their reputation as having a much more roving disposition than 

 the brook trout. 



