SALMON— SMOLTS MIGRATING— GRILSE. 93 



altliou,c:li some excellent observers are still disinclined to believe that it is possible 

 these iish can increase so rapidly in size that one descending' in May a few ounces 

 in weight could bo capable of returning within two or three months as a 4 lb. or 

 5 lb. grilse. But it is not impossible that as we see differences in the periods of 

 descent of smolts, so some may return in one season, the remainder in tlio 

 succeeding year.* It is remarkable that grilse do not commence ascending until 

 two or three months subsequent to the descents of smolts, whereas had they 

 been upwards of a year in the sea it would appear strange Avhy some few at least 

 had not previously put in an a{)pcarance, this invariable absence from the nets 

 almost seeming to point out the probability that they arc entirely absent. 



It has been maintained that grilse are a distinct species of the SalmonidiB, but at 

 Howietoun, as I shall have to observe under the head of " salmon raised in fresh 

 waters," the par turned to smolts, and subsequently to grilse, f and from these last 



however, caught about the same time at Inverness by Mr. Hutchinson, and each weighed about 

 5 lb. In the river Berridale, in Caithness, Mr. Alexander Morrison in the year 1794, in the month 

 of May, marked five smolts or salmon fry, in such a manner, that if ever any of them returned 

 to the river, and were caught, no doubt could remain as to their being of the number so marked. 

 Two of these smolts, then become grilse, he caught in six or seven weeks after thoy had been 

 marked, when they weighed about 3^ lb. each. In April following, he caught another of the 

 number, then a salmon, which weighed between 7 lb. and 8 lb. ; and in the month of August he 

 caught a smolt weighing 8 lb." He also stated : "I ascertained by experiment that a grilse which 

 weighs 6 lb. in February after spawning, will, on its return from the sea in September, weigh 131b." 

 (p. 13). 



Sir W. Jardine writing in 1835 respecting the fisheries in Sutherlandshire, in the Edinhurgh 

 New PliilosophicalJournal, T}. 47, observed: "Last spring several thousands of fry were marked 

 in the different rivers, among others, by Mr. Baigrie, in the Laxford and Dinard, on the west 

 coast. In the Laxford, the first grilse (marked iir April as fry) returned on the 25th June, and 

 weighed 3 J lb. Many others were got during the season from this weight to 6i lb., returning to 

 the rivers where the fry were marked, which was known by a particular mark being used in each, 

 and showing that a return to their breeding-ground was as frequent, or rather as constant, as 

 among the higher animals." 



Mr. Young of Inrernliin, in 1843, observed that "in the months of April and May, 1837, he 

 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 he caught a considerable number on their return to the rivers, all in the state of grilse, 

 and varying from 3 lb. to 8 lb. according to the length of sojourn in the sea. Again in 1842 

 similar experiments led to similar results. In the Tweed numbers of smolts have been 

 marked by a silver wire having been passed through and fastened to the back part of their 

 tails. None were obtained the same year, but the experiment was repeated the succeeding 

 season, and several were taken as grilse. The Duke of Roxhurghe, on May 14th, 1855, had a 

 smolt marked by the insertion of a peculiar shaped wire through its gills ; it was retaken 

 July 21st, 1856, as a grilse, weighing G^ lb. Brown, Stornwntfiehl Experiments, remarked that in 

 May, 1855, 1300 smolts were marked at Stormontfield by cutting off the adipose fin, and 22 were 

 recaptured as grilse the same summer, the first on July 7th, 1855, when it weighed 3 lb. ; one on 

 the 20th, 51 lb., 24th, 5 lb., 30th, 7^ lb., 31st, O^lb., August 4th, 7^ lb., and on the 14lh, 8 lb. 



Those left in the pond, continued Mr. Brown, though healtJiy at the end of the year had not 

 increased in size very much, many male pars were full of milt and some of the fry were very 

 small, not being much above three or four inches in length (pp. 49, 51). Also, that in 1859 " the 

 first marked grilse was taken six weeks after leaving the ponds, and had increased from not more 

 than 1 oz. or 1.^ oz. to 3 lb. 3 oz." (p. 78). That "the experiments here have shown that 

 marked grilse of one year return as salmon the next : that all the smolts of one year do not 

 return the same year as grilse, the one half returning next spring and summer as small salmon" 

 (p. 92, 93). 



* Buckland (Nov. 9th, 1879) remarked that in his opinion some may return to the river the same 

 year they go down as smolts, but that some stay one, if not two years in the sea. " Grilse have 

 even been captured of the extraordinary weight of 14 lb. Such a striking augmentation of size has, 

 in all probability, resulted from the operation of several causes. A longer stay than usual on the 

 feeding-grounds, or a richer and more abundant supply of food, would have a marked effect in 

 the acceleration of growth. Other causes on the contrary may tend to retard their natural 

 development. It is not unlikely that grilse leave the sea in shoals on their return to the fresh 

 water. On such a supposition it is easy to understand how straggling fish may return in their 

 company, which have not been on the feeding-ground more than one-hali. of the time which the 

 shoal itself has spent in the ocean. To such circumstances the small size of occasional grilse of 

 only a single pound in weight may, with much probability, be ascribed" (Ramsbottom, On t]ie Salmon, 

 1854, p. 22). 



t Br ov^B, Stormontfield Experiments, observed that " these experiments have shown that smolts 

 were caught, marked as grilse the first season, and salmon the second " (p. 94). Ramsbottom, 



