AQUATIC PLANTS IN" POND CULTURE. 21 



REMOVAL OF VEGETATION TO PERMIT SEINING. 



For the removal of vegetation in ponds preliminary to the periodi- 

 cal seining oj^erations the pond cultiirist must depend upon mechani- 

 cal methods of clearing away the foliage. It is customary to begin 

 the removal of the young fish for distribution soon after their yolk 

 sac is absorbed, or after the fry have been feeding but two or three 

 weeks. At this season the growth of vegetation is not so exuberant 

 as later in the summer, and the firet crop of fish may sometimes be 

 collected by seining around the edges of the ponds without the pre- 

 liminary clearing away of the vegetation. Often, however, the shal- 

 lower portions of the ponds must be cleared before even the first crop 

 of fish can be removed. Later the fish will have sought the deeper 

 portions, from, wliich they can not be removed without first drawing 

 off the water. In the latter process the foliage, if left, would settle 

 down as the water diminished, entangling the yoimg fish or smother- 

 ing them, and it is accordingly necessary to clear away the plants 

 before drawing off the water. The methods of removing the foliage 

 are thus reduced to a mowing process under water, varied and 

 adapted as conditions and circumstances may demand and ingenuity 

 may devise. The methods and apparatus here described have been 

 employed at pond-culture stations but are also applicable to natural 

 ponds where the character of the bottom permits of seining opera- 

 tions. 



At the Fish Lakes station the removal of the aquatic foliage was 

 accomplished by mowing with ordinary scythes such as are used in 

 a hayfield. The shallower portion of a pond was mowed first, and 

 the water was then partially drawn off', so that it did not reach above 

 the armj)its of the mowers, its average depth being from 3 to 4 feet. 

 The cut foliage rose to the surface and was carried to the shore in 

 boats. 



When it is desired to transfer young fish from the ponds at North- 

 ville, Mich., the slash boards are removed from the overflows and 

 the water drawn down. As it recedes from the banks a few feet, 

 men rake the Chara into piles, taking care that no young fish are 

 destroyed in the operation, and continue this process until all the 

 water and young fish are confined to the kettle of the pond. It was 

 formerly customary to remove the vegetation by the use of teams, 

 but experiments show that if left exposed for two weeks the Chara 

 settles and finally disappears after the pond has been refilled. The 

 presence of this decaying vegetation ought to stimulate the breeding 

 of more or less insect life for young fish to feed upon. 



The method of separating plants and young fish at the Mill Creek 

 station of the Michigan Fish Commission is described by the superin- 

 tendent, in su})stance, as follows: A space 10 feet wide around the 

 pond is first cleared, of foliage with a common iron-toothecl garden 

 rake, a piece of galvanized-wire netting of one-fourth-inch mesh 

 being fastened to the back of it to prevent its becoming entangled 

 in the weeds. (Any tinsmith can solder the wire cloth to the iron 

 back.) After this has been done a homemade rake is used to remove 

 the foliage from the deeper water of the pond. The rake is of rude 

 construction, consisting of a cedar pole 8 feet long and 4 or 5 inches 

 in diameter, provided with teeth 6 inches apart and 12 inches long. 



