636 U. S. BUREAU OF FISHERIES 



stage, more as a curiosity than anything else. No particular diffi- 

 culty was experienced in raising these fish, but the expense entailed 

 in feeding them for a prolonged period, and the impossibility of doing 

 so unless large ponds were constructed at great expense for the purpose 

 of holding them during the feeding period, prevented the general 

 adoption of the rearing system. 



For some years certain fish culturists and others had contended that 

 the planting of fry just after they had absorbed the umbilical sac was 

 an economic mistake, claiming that at this age they were weak and 

 comparatively sluggish in their movements, and would fall easy prey 

 to their numerous fish, bird, and other enemies. The late Robert D. 

 Hmne, who built and operated a hatchery on the lower Rogue River, 

 also one on the upper Rogue River, which the United States Bureau 

 of Fisheries operated for some years, was one of the first to take up 

 the rearing of salmon fry on any scale. 



In time these objections bore weight, and a few years ago the con- 

 struction of ponds in which fry could be held and fed until they had 

 reached a size which would insure them at least an even chance for 

 their lives was undertaken all along the coast, with the result that 

 to-day there is a pond capacity for about one-half of the total capacity 

 of the various hatcheries. 



Most of the nursery ponds have been constructed near the hatch- 

 eries and usually comprise oblong trenches dug in the earth and walled 

 wdth cement and stone. 



In Oregon the State authorities found that the best results in pond 

 rearing were obtained by using creek or natural ponds, which were 

 made by placing dams across the small streams in the vicinity of the 

 hatcheries. When first taken from the hatching troughs the fry are 

 placed in the artificial ponds imtil the danger from spring freshets in 

 the small streams is over. They are then transferred to the natural 

 ponds, where the continual flow of fresh water, and the logs, rocks, 

 etc., which provide shade and shelter, afford more natural conditions, 

 and in which the natural food of the fry supplements the artificial 

 food provided by man. 



A big advantage in connection with the use of natural ponds is the 

 comparatively small expense involved in providing for them as 

 compared with the large expense involved in the construction of 

 cement ponds. 



The young fry show when they are ready to feed by darting to one 

 side or the other when small particles of food are dropped in the water 

 and float past them. For the first few weeks they should be fed 

 regularly and as often as six times a day, and the earlier in the day 

 the feeding begins and the later it continues at night the better. 

 Two hours after feeding they will be found to be ravenously hungry, 

 and as they grow much faster for frequent feeding great care should 

 be taken to see that they are well fed. If not fed sufficiently, they 

 ^vdll bite at one another and cause more or less mortality among 

 themselves. 



