MATURITY 1^2 



their first descent as smolts may vary is at least suggested, if it is not 

 proved, by examination of the scales. Out of the 45 sets of scales of 

 Loch Lomond fish examined by Mr. Hutton and myself, one fish, a late 

 descending smolt (Fig. 30) had not reached the sea at all. Of the 44 

 others the scales indicate a residence in salt water subsequent to descent 

 thus : — 



23 remained in the sea over o winters (Fig. 45). 



16 remained in the sea over i winter (Fig. 46). 

 4 remained in the sea over 2 winters (Fig. 47). 

 I remained in the sea over 3 winters (Fig. 48). 

 The 23 first noted of course ran as whitling in the same year as they 

 descended as smolts, and it is interesting to note that of these, as I 

 have stated, 5 showed evidence of spawning. 



I am unable, with the data at my command, to deduce any general 

 principle as to the effect which continuous residence in the sea without 

 spawning may have upon the growth of the sea-trout in contrast to its 

 rate of growth when spawning has early occurred and thereafter been 

 continued each year. The variations are bewildering even in the few 

 data which I possess. For example the fish which remained over 3 

 winters in the sea without spawning, whose scale is shown in Fig. 48, 

 weighed 1 1 lb. Its record is as follows : — 



Fresh-water life ... ... ... 3 years] 



Sea life without spawning ... 3 years [si vears= 1 1 lb. 

 Sea life with spawning ... ... 2^ years J 



fhe fish which remained over 2 winters in the sea without spawning, 



whose scale is shown in Fig. 47, weighed 4^ lb. Its record is : — 



Fresh-water life ... ... ... 3 years) 



Sea life without spawning ... 2 years [51 years = 4^ lb. 

 Sea life with spawning ... ... | year j 



But I give (Fig. 49) the scale of a fish which spent 3 winters in the sea 

 without spawning, and although 1 1 years old weighed only 2^ lb: Its 

 record is : — 



