ARTIFICIAL PROPAGATION OF STURGEON. 7 



Two of the most important deductions from the investigations 

 made during the experimental work are that sturgeon eggs become 

 ripe and suitable for impregnation only when the male and female 

 fish are kept together in the same pond or reservoir and that the 

 spawning act takes place probably only at night. These two observa- 

 tions explain why it has always been very difficult to get npe eggs 

 from sturgeons caught during daytime or kept in ponds or inclosures 

 with the male and female fish in separate compartments. 



In our experiments, specimens of .4. ruthenus have been held in 

 large ponds, and their eggs have become ripe. Russian sturgeon have 

 l^een retained in a reservoir about 32 feet long, 11 feet wide, and 6 

 feet deep, supplied with a current of water pumped directly fi'om 

 the Ural River. One night these fish spawned, and two days later 

 there were found in tlie mud at the bottom of the pond thousands of 

 eggs. Some of those fish hatched into healthy fry, but, as is always 

 the case under natural conditions, most of them had not been fer- 

 tilized, and therefore tliev perished. 



With regard to artificial propagation of sturgeon, as elaborated 

 by Russian fish-cultiirists in the hitest work, the methods have been 

 as follows : As tlie eggs flow from the female sturgeon they have a 

 tendency to become united into a glutinous mass, which must at 

 once ha prevented. We received good results by stripping the eggs 

 into a wire screen, washing them thoroughly with river water, and 

 then putting them in a tin pan and fertilizing them with milt diluted 

 with water. Several minutes hiter, before the eggs had become 

 sticky, we again washed them thorouglily with river water, which at 

 this time in the Ural and Kura Rivers is very turbid and of a yellow 

 color, because of the enormous quantity of chiy and sand in suspen- 

 sion. By such use of muddy river water analogous to the employ- 

 ment of swamp muck or of 'starch for overcoming the adhesiveness 

 of pike-perch eggs in the United States, we counteracted the sticki- 

 ness of the sturgeon eggs, which thereafter lose that quality and 

 become easv to handle in any fish-liatching ai)paratus. We ol)tained 

 quite. goodVesults in using two very different kinds of apparatus, 

 namely, the Williamson trough and the Chase jar; but in both cases 

 we preferred to employ not running water, which is always a little 

 muddy, but filtered water without circulation and with constant 



aeration. ,111 



After three or four days of development the eggs hatched, and 

 thousands of fry were obtained. For the first four or five days the 

 young do not require anv external food, liaving a sufficient quantity 

 of nourishment in their yolk sac; but after that period we introduced 

 into the troughs and jars living food consisting of the smallest 

 fresh-water crustaceans (Daphnia, Bosmina, etc.) collected in small, 

 warm waters with fine-meshed nets. The ivy soon begin to seai-ch 

 for these crustaeeans. When they become larger and accustomed 

 to take food, we begin to feed with chopped earthworms, of which 

 young sturgeon are verv fond. Fed in this way sturgeon grow very 

 rapidlv, attaining during the first month a length of about \\ inches 

 and during five months 10 to 11 inches. Fry of two to three months 

 have already begun to closely resemble the adults and are very pretty 

 fish. 



35286°— 21 J 2 



