76 U. S, BUREAU OF FISHERIES. 



the year of a record collection of trout eggs, the total in round 

 numbers amounting to 2,056.000, or 21^ per cent more than in any 

 previous year in the station's history. 



At the Neosho station 848,000 rainbow-trout eggs were collected 

 between November 16 and February 19. This stock was materially 

 reduced by losses, both in the egg stage and subsequently, and from it 

 181,965 fingerlings Nos. 2 and 3 were realized for distribution, with 

 about 10,000 remaining on hand at the end of June. 



It having been found that the best eggs at this station are the 

 product of very young iish, a systematic policy of selective breeding 

 and liberal feeding, with the object of increasing the percentage of 

 early spawners, has been in progress for some time. The elforts in 

 this direction are apparently bearing fruit, as the proportion of 

 spawning trout under 2 years of age is steadily increasing, being 

 now about double what it was before the experiments were instituted. 



A slight deviation from past methods was made in the feeding of 

 fry and small fingerlings. For the purpose of varying the diet 

 the fish were given clabbered milk twice a day and beef heart three 

 times a day. They took the milk readily and seemed to thrive 

 equally as well as when fed exclusively on heart. 



No definite cause could be assigned for a slight loss occurring in 

 each lot of rainbow trout as they attained a length of 1^ inches. A 

 few of the fish showed what appeared to be an extremely minute 

 threadworm in the intestines, but at 375 diameters these were hardly 

 distinguishable. By immediately cutting oif all food for a period of 

 24 hours and then giving nothing but clabbered milk for tlie suc- 

 ceeding four days the loss was reduced to normal proportions. 



Late in April a more serious epidemic broke out in the troughs 

 containing rainbow trout 2 or more inches in length, the more promi- 

 nent symptoms being distortion of the head, faded-appearing gills, 

 and an abnormally dark color, the latter being most pronounced 

 among badly affected individuals. The kidneys showed disintegra- 

 tion with crystals. A careful examination by the bureau's pathol- 

 ogist failed to disclose the cause of the disease, but it is believed 

 it may have been due to the presence of mineral substances in the 

 water supi)ly. There was no evidence of it among fish that had 

 been removed from the hatchery to rearing ponds as fingerlings No. 

 1|, and thinning out of the young fish and early removal from the 

 hatchery to rearing pools will hereafter be resorted to in the hope 

 that a recurrence of the trouble may be averted. 



The disease gyrodactylus developed in one pool of No. 2| finger- 

 ling trout early in May, but was quickly dissipated by immersing 

 the fish for a fraction of a minute in a i : 15 solution of pure cider 

 vinegar. Ichtliyophthirius made its appearance in one pond, but 

 loss from this cause was prevented by immediately transferring the 

 affected fish to another pond where they could be held in a good 

 flow of running water. 



Excellent results were attained in the hatching of a lot of 50,000 

 eggs from wild rainbow trout received on June 10 from the Bozeman 

 (Mont.) station. The product of these eggs will be reared and 

 reserved for a brood stock at Neosho and auxiliary stations. 



The result of the season's work in the propagation of pond fishes 

 at Neosho station was the poorest experienced in many years. This 

 is attributed largely to adverse climatic conditions. An almost 



