TENDING THE PONDS. 239 



baskets can be replaced without any injury to the 

 ova that remain in them. The breeding trenches 

 described in the paragraph preceding this, des- 

 tined for the propagation of stock or store salmon, 

 should never be disturbed. 



The trenches of artificial ponds do not require 

 to be made so deep as the excavations salmon 

 make when they form their own spawning-beds, 

 because, in ponds rightly constructed, the volume 

 and force of water in them, and passing over and 

 through the gravel of the artificially constructed 

 beds, scarcely ever vary. It is not so with the 

 water in which salmon form their breeding-beds. 

 They are subjected to great variations in volume 

 and strength of water, and if they were not deeply 

 excavated, under a sufificiently resisting weight of 

 gravel, it and them would be frequently w^ ashed 

 away, and destroyed by the force of winter 

 floods. 



When the spawn is fairly deposited in the 

 ponds, either by means of trenches or wire 

 baskets, all that the breeder has to do is to see 

 daily that the grating through which the water 

 feeding the ponds flows is free from all obstruc- 

 tions — that the stream flows into ponds fairly and 

 regularly, and that their supply of water is always 

 of the proper uniformity, neither diminished by dry 



