A STUDY ON TROUT AND YOUNG SALMON. 295 



to the various trout forms of the fresh waters. Having reached 

 the sea these fish become sea trout. 



First of all I was made aware of this fact by obtaining in 

 my nets in the sea, especially in or around river mouths, trout 

 which differed considerably from the sea trout. These trout 

 differed in colour considerably from the general colouring of 

 the sea trout and possessed more of the gay and bright 

 colours peculiar to the trout forms of the fresh waters. For 

 comparison I have several times in mountain lakes caught 

 trout and satisfied my self as to their similarity to the sea 

 trout. Whether fry or young of the fresh water forms are 

 to be found among the young trout emigrating in spring, I 

 have been unable accurately to decide, as no marked diffe- 

 rence is noticeable between the young of the sea trout and 

 the young of other trout forms. On this occasion I have com- 

 pared the young of mountain or lake trout as well as the young 

 of trout from brooks where sea trout cannot ascend, with the 

 young sea trout emigrating from our rivers in spring. I have 

 been unable to find any marked difference between them, and 

 the colours especially are in the main features strikingly alike. 

 Even such a detail as the anal fin being oHvegreen or brownish 

 yellow with blackish forepart and a creamy streak along the 

 front edge is constantly noticeable in all such young which 

 I have examined. Only after having reached the sea and for some 

 time lived there do the young of the sea trout acquire the strong 

 silver colour and in other respects become distinguished from 

 the other trout forms. 



Thus a recently emigrated freshwater trout may clearly be 

 recognised as such in the sea, only when it belongs to older 

 stages. 



However I deem it highly probable that such an emigration 

 of freshwater trout to the sea also includes younger stages, and 

 further that this emigration may take place to an extent not 

 unimportant to the economy of the sea trout. 



