344 MB YOUNG ON THE GROWTH OF GRILSE AND SALMON. 



anticipate that a larger number will become smolts in about a twelvemonth after 

 then* first spring, than was the case with those observed in Dumfriesshire. This 

 may possibly arise from then- being with me so much nearer the salt-water, of 

 which I find the influence on salmon, in all its stages, to be most remarkable. I 

 conceive, however, that the question of the true history of this important species, 

 from the egg to the smolt, has been set at rest. To connect that early state with 

 the grilse, and the latter link with the adult salmon, is therefore the object of the 

 present communication. My long continued superintendence and control of some 

 of the finest and most productive salmon fisheries in Scotland, and the peculiar 

 position I occupy, as residing almost within a few yards of the cruives upon the 

 noted river Shin, afford me advantages which I trust I have not altogether ne- 

 glected. 



I have now made many experiments on these fish, taking up the subject 

 where it was necessarily left off by Mr SHAW ; and I find, that, notwithstanding the 

 slow growth of the parr in fresh water, such is the influence of the sea, as a more 

 enlarged and salubrious sphere of life, that the very smolts which descend into it 

 from the rivers in spring, ascend into the fresh waters in the course of the imme- 

 diate summer as grilses, varying in size in proportion to the length of then- stay 

 in salt water. 



Thus, in the months of April and May ef the year 1837, I marked a great 

 number of the descending smolts by making a peculiar perforation in the caudal 

 fin with a pair of small nipping irons constructed for the purpose ; and in the 

 months of June and July I caught a considerable number on their return to the 

 rivers, all in the state of grilse, and varying from 3 Ib. to 8 lb., according to the tune 

 which had elapsed since their first departure from the fresh water, or, in other 

 words, the length of their sojourn in the sea. 



Again, in April and May of the present season (1842), I marked a number of 

 descending smolts, by clipping off the dead or adipose fin upon the back, and care- 

 fully replacing them in the river. In the course of June and July following, I 

 caught them returning up the river, bearing my peculiar mark, and agreeing with 

 those of 1837, both in respect to size, and the relation which that size bore to the 

 lapse of time. Two of these smolts, as marked last spring, and which I caught 

 again as grilse, I have transmitted to the care of Mr GOODSIR, College of Surgeons, 

 in whose hands they may be seen for the satisfaction of the curious or the scep- 

 tical. 



I have no doubt that many who argue on supposition, not on facts, may ask, 

 how, when salmon from the ovum to the smolt are so slow of growth, their ad- 

 vance from the smolt to the grilse should be so rapid ? In regard to this, I can 

 only state the fact as I have repeatedly ascertained it ; and it is not the less a 

 fact, although some of the final causes which produce it may be uncertain or 

 obscure. My own opinion is, that it is owing to their change of domicile from 



