374 MR SHAW ON THE GROWTH AND MIGRATIONS 



ling, and is actually one of the 90 individuals marked as fry in May 1836, though not 

 captured on its first return. It was retaken on the 1st of August 1837, fifteen 

 months after being marked as a fry on its way to the sea. It weighed about two 

 pounds and a half, and represents pretty correctly the average size of sea-trout 

 on their second migration from the sea. These older fish usually make their ap- 

 peai'ance in our rivers in greatest abundance in the months of May and June. In 

 consequence of the specimen now before you having been in fresh water for a 

 considerable time, it has acquired a dusky exterior. To shew the better and 

 brighter aspect of the species, I have placed beside it a specimen of corresponding 

 size taken from the river in May. 



In consequence of the herling having greatly abounded in the river Nith in the 

 summer of 1834, 1 took the opportunity of marking a great number of them (524), 

 by taking off the adipose fin, and returning them into the river. During the fol- 

 lowing summer (1835), I recaptured 68 of the above number as sea-trout, weigh- 

 ing on an average about 2^ pounds. On these 1 put a second distinct mark, and 

 again returned them to the river; and on the next ensuing summer (1836) I re- 

 captured a portion of them, about 1 in 20, averaging a weight of 4 pounds. I 

 now marked them distinctively for the third time, and once more returned them 

 to the river, also for the third time. On the following summer (23d day of Au- 

 gust 1837), I recaptured the individual now exhibited (No. 11) for the fourth 

 time. It then weighed 6 pounds. This fish exhibits the nature of the several 

 different marks put upon itself and the other individuals, as they were succes- 

 sively recaptured, from year to year, on their return to the river. These marks 

 were as follows : 1st, The absence of the adipose fin (herlings in 1834) ; 2d, One- 

 third part of the dorsal fin removed (sea-trout in 1835) ; 3d, One-half of the anal 

 fin taken off (large sea-trout in 1836). Captured and killed in 1837.* 



I also marked, in the summer of 1835, about 120 sea-trout, by putting cop- 

 per-wire into the dorsal fin of one-half of that number, while I marked the other 

 half by twisting a small portion of the copper- wire round the right maxillary 

 bone. Of the latter group I recaptured five individuals the following summer, 

 and found that they also had gained an average increase in weight of 1^ pound. 

 None were recaptured with the wire in the dorsal fin* which I attribute to the 

 circumstance of that part being of too fragile a nature to retain the wire for a 

 sufficient length of time ; and therefore, though they no doubt returned, they 

 could not be recognised. 



From the numerous and long-continued experiments which I have thus been 

 conducting for many years on this species of migratory trout, I have come to the 



* Where only the cartilaginous portion of the fins is taken off, they frequently prove defective 

 marks, as nature always makes an effort to heal and restore those important organs of locomotion, when 

 injured. But when taken off close to where they articulate with the body, the parts are never restored. 



See, as examules, the dorsal and anal fins of No. 11. 



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