NATURAL HISTORY OF THE SALMON. 73 



instance, the net-fishing used to be voluntarily stopped 

 in some rivers before the run of grilse had nearly ceased, 

 whilst in others, the fishing was carried on for six weeks 

 later, or tiU after the conclusion of the run of grilse ; and 

 the difference is great between different rivers and estuaries 

 as to the natural facilities for capturing a fish which does 

 not rest and loiter like the adult salmon, but rushes on, 

 if Mr. Mackenzie will permit us the phrase, with the 

 ardour of youth, and of youth, too, on its marriage- 

 jaunt. But such cases do not destroy the fact that 

 salmon and grilse are always either both, or neither, in- 

 habitants of any given river ; and comparatively few of 

 those cases even disturb the fact that they are found 

 present in certain proportions to each other, and just in 

 such proportions as we might expect to find between the 

 adolescents and the adults of the same species. 



Take next the test furnished by a comparison of 

 season with season, instead of river with river. Mr. 

 Mackenzie says, " It is a common remark amongst fisher- 

 men, that though the salmon fishery may be bad, still 

 the grilse fishery may be productive ; each fishery vary- 

 ing in quantity to correspond with the favourable or 

 unfavourable season in which they were spawned — 

 clearly showing two distinct fisheries and nature of 

 fish." Not at all. The " common remark among fisher- 

 men," the accuracy of which we have no motive to deny, 

 does not necessarily imply two distinct kinds of fish ; 

 but, at least as probably, different broods of the same 

 fish, born in different years and representing different 

 spawning seasons. Not only, however, is Mr. Mac- 

 kenzie's fact as to grilse being sometimes abundant in 



