EESULTS OF SALMON MARKING 89 



second fish may have spawned in the interval of 

 447 days, which is, of course, the interval between 

 marking and recapture, not necessarily an indication 

 of the length of time spent in the sea. Yet even 

 without the second fish we have the first and third 

 each with a precisely similar interval, yet one with 

 twice the increase of the other. That these bull- 

 trout do go to the sea may be inferred from the fact 

 that sea lice are commonly found upon them, as well 

 as gill maggots, when they come into the river. 

 They are by no means confined to the Tay, but occur 

 sparingly in other parts of the country. Personally 

 I have noticed them also in the Ness, Helmsdale, 

 and Dee. Giinther has described them from the 

 Beauly, and Parnell from the Forth. 



The last series of observations on the habits of the 

 salmon to which reference may here be made has 

 been obtained by the marking and recapture of clean 

 run fish. Now the habits of clean run salmon, 

 otherwise spring fish, have given rise to much dis- 

 cussion, very largely because some rivers contain 

 spring fish, while others, for no apparent reason, do 

 not. It is proposed in another chapter to deal with 

 early and late rivers, and in this rather to deal with 

 the habits of the spring fish after it has entered its 

 " spring river." At the outset, however, it seems 

 necessary to recollect that the habits of spring fish 

 seem to be subject to considerable variation under 

 the conditions which obtain in difierent countries. 

 In Norway, Iceland, Lapland, and possibly elsewhere 

 clean summer fish ascend freely in snow water. In 

 Scotland " snaw bree " prevents fish running ; by 



