FISH-CULTURAL PRACTICES IN THE BUREAU OF FISHERIES. 723 



Soon after the yolk sac has been absorbed, or after the fry have been feeding 

 for two or three weeks, a portion of them are removed from the ponds and dis- 

 tributed to the waters they are to stock. The first crop may often be obtained 

 by seining around the edges of the pond without the prehminary clearing away 

 of vegetation, and for this purpose a novel casting seine has come into use at 

 Northville, Mich. The web is rigged upon two long bamboo poles, so that the 

 device may be operated entirely from shore, without roiling the water or unduly 

 disturbing the fish." 



After the young fish have sought the deeper portions of the ponds, pre- 

 liminary to drawing off the water to effect their capture, it is necessary to remove 

 the aquatic vegetation, a process of much labor and expense, consisting in 

 general of mowing under water, and carrying away the foliage by means of 

 pitchforks and boats. Various methods and devices for this purpose have been 

 evolved at the different stations, as described elsewhere.'' 



Ordinarily the assorting of young pond fishes by size is accomplished by 

 hand manipulation with a scaff net. To some extent, however, the separation 

 may be accomplished by regulating the size of the mesh in the nets used to 

 effect their capture. The superintendent of the San Marcos, Tex., station 

 suggests having an ample bag to the dip net in which quite a large lot of fish 

 may be taken from the tub or other retainer, then passing the net gently to 

 and fro in the water to allow the fry and smaller fish to escape, while the larger 

 ones are retained. This method is principally used for assorting black bass, as 

 it frequently happens there are schools of both fry and fingerlings in the ponds 

 at the same time. Nets of one-fourth inch square mesh will permit the escape 

 of all fish up to I K inches ; one-half inch square mesh will permit the escape of 

 all fish under 3 inches in length. 



At the Cold Springs, Ga., station the superintendent uses a box 3 or 4 feet 

 long by I foot wide and i foot deep, and water-tight to a depth of 2 inches. 

 Above this 2 inches one side is covered with wire cloth instead of being closed in, 

 the size of wire mesh being regulated for known sizes of fish. The box is par- 

 tially submerged in the pond in which it is intended to place the smaller fish of 

 a lot to be assorted. The young fish as caught are placed in the box, and then are 

 left undisturbed for an hour or two. At the end of this time the smaller fish 

 will have escaped from the box through the screen into the pond, when the 

 box with the larger fish remaining in it may be transferred to another pond and 

 emptied, or the contents may be poured into a suitable receptacle for transpor- 

 tation by tipping the box toward its solid side. Square-meshed galvanized 

 cloth is used for the screen, and if the fish are given plenty of time to separate 

 none of them are gilled, hung, or otherwise injured. 



1 Fuller, op. cit. 



6 Titcomb, J. W. : Aquatic plants in pond culture, Bureau of Fisheries Document 643. 1909. 



