CULTURE OF THE MONTANA GRAYLING. 7 



before the yolk sac is entirely absorbed answers a good purpose. 

 Liver emulsion rendered as fluid as possible, and then strained through 

 ordinar}^ mushn, will serve to tide the fry over the precarious stage 

 until they are a month or six weeks old, when they can be fed the 

 same as trout fry ; but during the first stages they must be watched 

 closel}^ and fed much more frequently than trout fry. If fresh blood 

 can be procured and stirred until it becomes a homogeneous fluid, 

 free from clots, it can advantageously be supplied either straight or 

 mixed with the strained liver emulsion. But, owing to the very 

 small size of the grayling fry, artificial feeding is under all circum- 

 stances quite a problem. At the Bozeman station they have been 

 reared to maturity in the manner mentioned with a loss of from 50 to 

 70 per cent; and the mature fish have been stripped and the eggs 

 hatched and fry planted. This has been done several seasons, though 

 only a portion of the females yielded good eggs and many males were 

 not in good breeding condition, possibly from a lack of their natural 

 food and from being kept in spring water. 



The fry should be transferred to shallow, sunny nursery ponds with 

 a good current of stream water, of a higher temperature than spring 

 water, if possible — say from 55° to 60"^. They begin to forage for their 

 natural food as soon as placed in the pond, and are exceedingly active 

 and industrious. If the water is found to contain an abundance of 

 their natural food, which can be determined by examination with 

 the microscope, they will do well. In addition, however, it is well 

 to feed the fry at least six times a day for several weeks; otherwise 

 they may begin to eat each other, being very cannibalistic. Owing 

 to this tendency it is, moreover, advisable to begin with two or three 

 times as many fry as it is desired to rear. 



Output of the government grayling hatchery. — The following table is 

 a statistical resume of the results of grayling propagation by the U. S. 

 Bureau of Fisheries in the last decade. 



Output of Grayling from the U. S. Fisheries St.\tion at Bozeman, Mont., 



1898-1907. 



o 



