INTRODUCTORY 43 



clue to the characters of the various so-called species, and relegate 

 these different trout to a single form, in which numerous local races are 

 to be found." This is, of course, a very easy way of evading all 

 difficulties, but it does not dispose of them. I think the facts rather 

 point to such a differentiation as f have suggested above. 



What purpose would the solution of such problems as I have 

 here considered serve ? One never can tell of course in what direction 

 definite knowledge may ultimately prove useful. Something at least 

 is gained by the mere fact that the knowledge is definite. But there is 

 this further consideration. It has for some years been apparent that 

 the stock of sea-trout in once well-stocked waters has markedly 

 declined. Even as long ago as 1904 " The Spectator " feared that the 

 fish was " doomed to a not very remote extinction " ; and as recently as 

 August 1914, there appeared in " The Salmon and Trout Magazine " 

 a suggestive article on the decline of " White trout " fishing in Ireland 

 from the pen of that well-known writer " Corrigeen." Mr. Calderwood 

 also notes a general decline in the stock. 



If there is anything at all in the theory that there is any one, or only 

 one, species of trout in these islands whereof at any given point of time 

 a certain proportion is migratory and a certain proportion non-migratory 

 — the migratory habit per se in either case not being an indication of 

 '■ species " or even of " race " — then it necessarily follows that the 

 innumerable causes which have brought about a depletion of the stock 

 of trout in our once prolific rivers must be added to the many other 

 causes which have made for depletion in the ranks of the sea-trout. 

 If trout cease to exist in their pristine numbers in the main streams and 

 upper tributaries, whence, it may be asked, are the ranks of the sea- 

 trout of the estuaries to be reinforced? 



It is plain that such a question as this is far-reaching in its conse- 

 quences, for it at once opens out the further question whether our 

 fresh-water fishery laws dealing with trout have not been improperly 



