MANUAL OF FISH CULTURE. 191 



viscid in about 20 minutes after fertilization and stick together in 

 masses of various sizes. This interferes with their aeration, lowers the 

 vitality, and leads to the attack of fungus. The practice heretofore 

 adopted for overcoming this condition has been either to spread the eggs 

 in very thin layers on the hatching-trays prior to the development of 

 the adhesive quality, so that after becoming fixed they would be properly 

 aerated, or to stir them continuously for several hours in order to over- 

 come their adhesiveness. The high degree of success attending the 

 hatching of the glutinous eggs of the tiatfish and the wall-eyed pike 

 indicates that the difiiculty encountered with the similar sturgeon egg 

 may be readily overcome. By gently stirring recently fertilized eggs 

 with a mixture of dry cornstarch and water or fine swamp muck and 

 water, the tendency of tlie eggs to stick together and to other objects 

 is avoided through the partial coating of the individual eggs with 

 particles of starch or dirt. Other substances that will remain suspended 

 and not be dissolved in water can doubtless be employed to advantage. 

 Swamp muck is probably the best, because cheapest and most easily 

 obtained; 2 quarts of it may be mixed with 10 gallons of water, which 

 will be sufficient to render non-glutinous about 3 gallons of eggs; the 

 same j)roportioivof water, eggs, and cornstarch is recommended. After 

 being transferred to the hatching station, the eggs may be placed under 

 running water and the supertluous foreign particles washed away before 

 being placed in the hatching apparatus. 



The apparatus used in hatching sturgeon eggs has been chiefly boxes 

 placed ill the oi>en water of the river. The glutinosity being overcome, 

 there seems no reason why hatching may not be conducted in the auto- 

 matic shad jar or in other modern appliances. 



In the experimental hatching operations many eggs have been lost 

 through attacks of fungus, induced by the character of the apparatus 

 employed. The use of floating-boxes in open water has led to the loss 

 of eggs by storms, rough water, and sudden changes of temperature. 



The incubation period is about 7 days in water having a temperature 

 of 62° to 06° F. The outline of the fish appears in 48 hours. 



The question as to whether eggs of the common sturgeon can best 

 be hatched in fresh or brackish water is not yet determined, but the 

 indications are that brackish water is preferable. One reason is that 

 the eggs are less liable to attacks of fungus in such water. 



An attempt to rear artificially hatched sturgeon at North ville was 

 unsuccessful, owing to the failure of the young to eat. The mouth of 

 the sturgeon fry is very small, and the food is largely of a microscopic 

 character, consisting of unicellular algte, infusoria, insect larvae, etc. 



In Europe, where the sturgeon fisheries are vastly more important than 

 in America, the results of experiments in sturgeon-culture have scarcely 

 been as satisfactory as in this countr3^ No method of separating gluti- 

 nous eggs except by stirring seems to have been devised, and the same 

 difficulty has been found in obtaining fish with ripe spawn and milt. 

 The retention of fish in inclosures has not generally been successful. 



