32 FISH CULTURE. 



will be much fall between the ponds, the water should dis- 

 charge' at each outlet into a box or pool, and flow through 

 the race below in a gentle current. I' The water is thus 

 aerated without creating a rapid, which is unfavorable to a 

 spawning-ground. When the supply is small, the water 

 in a pond may back half way up the race which feeds it. 

 At the end of each raceway strips should be nailed perpen- 

 dicularly against the board sides, one set on each side at 

 the entrance into the pond, and another set three or four 

 feet above, so that wire gratings can be slipped in to secure 

 the spawners when they are driven from the race above. 



I would here impress on the beginner the necessity of 

 not allowing too rapid a stream in the raceways, or having 

 the water shallow, or gravel in the ponds where they enter. 

 If he does, the trout may find a more acceptable spawning- 

 place in the upper part of the pond, even in broad sun- 

 shine, than in the covered race above ; and if he attempts 

 to secure his spawners at the head of the pond with a seine, 

 he will frighten back into deep water those that might, 

 perhaps, enter the raceway. 



If the sides of the raceways are lined with boards, it 

 will not only secure them from the effects of frost and 

 prevent dirt from falling in, but will also be a protection 

 against muskrats. A hundred feet of hemlock or third 

 quality pine will cost but a trifle, and will line a raceway 

 fifty feet long. This is also the most effectual way of pro- 

 tecting the sides of ponds from these pests. On perfectly 

 level ground, however, if the water comes within a few 

 inches or a foot of the top of the bank, there is no harbor 



