18 THE LIFE OF THE SALMON 



fish would be allowed to remain in better proportion, 

 and the spawning season would in time harmonise 

 with the normal. A long belt of netting in a 

 river renders the weekly close time inoperative : 

 all early fish are captured, and only late-running 

 fish remain to keep up the stock. The statement 

 is by no means speculative. As will be shown at 

 greater length in a subsequent chapter, physio- 

 logical investigations of the most exhaustive kind 

 have shown that in widely different rivers geogra- 

 phically the ovaries of the salmon reach maturity 

 with remarkable seasonal uniformity. 



Reference has been made to the great variation 

 in the rate of growth of artificially reared smolts. 

 This does not seem to exist in the natural state. In 

 a series of smolt-netting experiments recently 

 made in the waters of the Tay below Perth it has 

 been found that, while various sizes of parr are 

 present, the silvery or migratory smolt is wonder- 

 fully uniform in dimensions. Great numbers of 

 smolts were passed under observation, and batches 

 were measured at intervals. They were found 

 to be from 5 to 6 inches in length (measuring to 

 the centre of the forked tail), and to weigh from 

 1 to 2 ounces. The netting and marking of Tay 

 smolts was commenced in the spring of 1903.* The 

 part of the tidal water where the fish were found 

 in greatest numbers was about four miles below 

 Perth. The river above this point is affected by 

 the tide for several miles, but the fresh water is 



* Twenty-third Report, Fishery Board for Scotland, Part II. 

 Appendix III. 



