152 American Fisheries Society 



emergence is not dictated entirely by the absorption of the sac. 

 When I emptied the gravel out of some boxes last spring I found 

 a few very large fry, fifty per cent longer and two hundred per cent 

 heavier than any I had previously seen come from the gravel. 

 I showed specimens of these fry along with others taken from the 

 natural beds and from the troughs to Mr. Cunningham, Mr. 

 Babcock, Mr. O'Malley and Dr. Gilbert and they were all 

 astonished at the contrast. 



I am convinced that the contents of the sac was not alone 

 responsible for this fine growth and the only feasible explanation 

 I can think of is that they fed on the dead eggs or on the other 

 fry, and this hypothesis is not unreasonable when we know they 

 will eat the bodies of their parents. I also contend that the large 

 eye, so evident in these fry, is a certain indication of strength 

 and a great aid in eluding their enemies. Fry that hatch head 

 first are weaklings and they have all small heads and eyes. Fry 

 hatched in water of high temperature, sixty degrees or thereabouts 

 are what we call "pinheads, " which means that their heads are 

 not developed. Examine the screen at the foot of a trough in 

 which the fry are hatching and you will find a preponderance of 

 small eyed or blind fry amongst the abnormalities. 



HATCHERY FRY. 



Hatchery fry are born under a handicap due to indirect water 

 circulation, handling, and the bad effects of light, and this follows 

 till they are liberated. They are on the move continually and the 

 contents of the sac is dissipated in energy, which is unnatural. 

 This movement is due to an inclination to get to the head of 

 the trough and fresh water, or to avoid the light, and, to prevent 

 piling up and consequent suffocation, they have either to be 

 riffled or the screens so placed to attract the fry under them. 



Provision against light usually consists of a few covers on the 

 troughs or blinds on the windows, and these are inadequate, and 

 the movements of the attendants has such a taming effect that 

 they will actually come to meet them if they are being fed. 



As I stated before, the smooth sides and bottoms of the troughs 

 are not conducive to fostering their hiding proclivities and this 

 soon becomes weakened; to counteract this somewhat I placed a 

 layer of fine gravel in the bottom of all the troughs last season, 

 with good results. 



