68 BULLETIN OF THE BUREAU OF FISHERIES. 



The fate of these precociously matured males has been a matter of some specula- 

 tion. It has been both claimed and denied that these died as do the sea-run adults 

 after the spawning season. The writer had an opportunity in the spring of 191 5 of 

 testing this. He was at this time marking series of young blueback (sockeye) and 

 chinook yearlings at the Bonneville (Oreg.) hatchery. Mature male chinooks, with 

 fluid milt which could be expressed, were frequently encountered. A number of these 

 were marked and held in a tank at the hatchery until July. Some had died in the 

 meanwhile, but in some of those which remained the testes had practically recovered 

 the normal immature appearance, and the characteristic coloration above described 

 was much less conspicuous than it had been at the time the fish were marked and placed 

 in the tank. The fish were apparently in perfect condition, and the scales show that 

 they were growing actively at the time they were preserved. It is not known whether 

 young males which have thus recovered from the effects of ripening the sex products 

 will migrate to the sea. 



PRACTICAL SUGGESTIONS. 



Although information of still greater practical value may be expected to come 

 from the study of the adult fish, some of the conclusions reached in this study appear 

 to offer important suggestions, which may be applied in practical fish culture, as to the 

 proper time for planting fry from the hatcheries. 



In the early days of the artificial propagation of salmon it was an almost universal 

 practice to "plant" ±he fry as soon as they were hatched. The mortality among the 

 helpless alevins, encumbered by the heavy yolk sac, must have been enormous, and the 

 hatcheries probably inflicted as much, or more, damage to the salmon runs as they did 

 service of value. More recently the tendency among the more intelligent and scientific 

 hatchery men has been to abandon the practice of planting alevins and to hold the fry 

 at least until the yolk sac is absorbed. The system of holding and feeding fry after the 

 yolk is absorbed has followed and with this, a not unnatural idea, that the longer the 

 fish are held and fed the greater the chance of their surviving. The vaUdity of this 

 assumption is, however, dependent upon several factors which have not been suffi- 

 ciently considered. The following more important ones may be mentioned here: 

 (i) The possibility of an increasing percentage of loss among fish so held which would 

 ultimately seriously reduce the number of fish planted; and (2) the effect of holding 

 fish beyond the normal time of migration on (o) their chances for survival and return 

 as adults, (b) the time of return as adults and whether they will return as spring or as 

 fall fish," and (c) the development of the normal feeding and protective reactions 

 (instincts) which are essential to their survival after planting. 



It is a well-known fact among hatchery men that salmon fry held and fed in hatchery 

 ponds will, after a time, "go bad." At such times the fish usually refuse to eat well 

 and show a distinct tendency to collect toward the lower end of the trough, tank, or 

 pond in which they are held. If persistently held the loss rapidly increases but finally 

 lessens as the critical period is passed, after which there is usually no more serious diffi- 

 culty experienced in holding the fish. This critical period usually comes after the fish 

 have been held and fed from 6 to 12 weeks — on the Columbia River in May or June 



a The greater value of fish composing the spring run has been noted above (p. 5). 



