EDITOR'S INTRODUCTION xv 



theories, but it has confirmed others, notably the 

 view expressed by Scrope that the parr remained in 

 fresh water longer than some people thought. The 

 method of reading and the significance of the scale- 

 markings are explained in the Appendix. Here it will 

 be enough to state briefly the results of the study. 

 They show that : 



1. The parr remain in fresh water normally for 

 two complete years before donning the silvery smolt 

 dress and migrating to the sea. They may, however, 

 migrate after one year, or remain in fresh water for 

 three years or even four. Mr. Hutton believes that 

 it is a question of nutrition, and he is probably right. 

 Rich southern rivers like the Avon or Test enable 

 parr to grow and develop more quickly than the 

 barren hungry waters of the north. But the two- 

 year period is probably most common in Great 

 Britain. 



2. Having gone down to the sea the fish may 

 remain there for one, two, three, or even four years 

 before it returns to spawn. This was a surprising 

 discovery, for it used to be thought that the fish ran 

 up every year, increasing in size between each visit. 

 But now it is proved that even a 5o-pounder may be 

 what is called a " maiden " fish, that is to say one 

 which has never been up to spawn before. 



3. There is a proportion of fish which spawn more 

 than once, more or less according to the old notion, 

 but it is relatively small. In the Wye, indeed, Mr. 

 Hutton has found that only 7 per cent of the fish 

 examined had spawned before, and only a fraction 

 of that fraction had spawned twice. Out of six 



