36 -RECENT EXPERIMENTS IN STURGEON HATCHING ON THE 



DELAWARE RIVER. 



BY BASHFORD DEAN, 



Instructor in Biology, Columbia College, New York City. 



The region of the Delaware River near its mouth has long been the seat of an 

 extensive fishery for sturgeon (Acipenser sturio ). At Delaware City, Del., the great 

 number of fish brought in daily to the wharfs during spawning time provides an oppor- 

 tunity especially favorable for experiments in artificial propagation. The studies by 

 Prof. Ryder ( published in the U. S. F. C. Bulletin for 1888) were here carried on in 1888, 

 and during the present season this station was again selected for experiments to be 

 made in behalf of the U. S. Commission of Fisheries. 



At the time of the writer's visit the fishermen were bringing daily to the slaughter- 

 ing wharfs from 50 to 100 fish; and among these (May 16, 17, 18, 1893) a number of 

 spawners were taken. There was thus abundant material for purposes of experin en t. 

 In the following paper the results of these test studies, in their bearing upon practi- 

 cal sturgeon-culture, are briefly reviewed. 



Fertilization. — The fertilization of the eggs, as known from former experiments,* 

 is easily accomplished. The milt and roe appear to even retain their capability of fer- 

 tilization under conditions seemingly very unfavorable. Ripe fish when brought into 

 the docks had been out of the water at least several hours; no precaution had been 

 taken to insure their careful transportation, and they were usually near the point of 

 death. In one case eggs were successfully fertilized which were taken from a fish 

 apparently lifeless. The milt appears to remain active as long as a. quarter of an 

 hour after the fish had been slaughtered. 



In the mode of fertilization care in details appears to be needless. Eggs from 

 ripe fish are readily fertilized whether extruded by pressure or obtained by excision. 

 In the latter case there is apparently no preference to be given to eggs from different 

 ovarian regions. Excision is certainly the more speedy and convenient method. The 

 eggs may be received with equal success in vessels earthen, metal, or wooden. 

 Especial cleanliness is not vitally essential — in one case eggs were fertilized in an 

 earthen bowl from which a fixing solution of concentrated acetic-sublimate had been 

 hastily rinsed. 



Milt may likewise be taken as well by excision as extrusion. In case the fish be 

 not actually "ripe" sufficient milt for a fertilization may often be obtained in a 



*In the United States those of Seth Green, 1875 (Fish Hatching and Fish Catching, Rochester, 

 1879); Prof. Ryder, 1888, and William Lanz, 1890 (Ohio F. C. Report). 



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