468 Memoir Sears Foundation for Marine Research 



that distinguish them as parr (p. 467), and they begin to acquire scales. As they 

 grow, they seek a new habitat, since the area that provided them with food and shelter 

 when they were younger is no longer adequate. Thus each one establishes a more or 

 less definite territory of its own as described by Katteberg (^5). The behavior pattern 

 has been described by Huntsman as follows {yo): "salmon . . . may become related to 

 particular local environments which may be called their homes. Such relation may 

 involve having a place or places for rest on the bottom, for stationing in a current, 

 and for cover, with more or less roaming as well as precise dashes in taking food." 



That parr move about in the parent stream now seems established. Huntsman 

 (6y: 399) found that freshets may greatly alter or destroy their home, and that this 

 and other factors induce or force the parr to descend from their spawning area to lower 

 waters of the parent stream, there to populate lakes as well as estuaries that have 

 fresh or brackish water (but not full sea water, which kills parr; 7^: 409). Some may 

 reascend varying distances upstream and populate places that are accessible; falls as 

 low as one foot seem to stop parr less than a year old. 



Subject as they are to many vicissitudes and to different environmental condi- 

 tions throughout their range, the populations of young vary widely at all times in abun- 

 dance as well as in size and growth relative to age (dependent mainly on food and 

 temperature) and hence in time of smoltification, not only from one general area to the 

 next and from one river to another in the same general area in different years, but even 

 from year to year in the same river. Such data as are available indicate that parr 

 throughout the Atlantic Salmon's range may spend anywhere from one to seven years 

 in the river before they become smolts, and that, generally, parr life is longer in northern 

 than in southern regions (Table 11). Most of the parr in America spend two or three 

 years in the river, but longer northward. In England and Scotland one- or two-year 

 smolts are the rule. In southern Norway it is usually three years, but northward, five-, 

 six-, or even seven-year smolts are common. 



In general, the fastest growing parr develop the soonest into smolts, but little is 

 known about the factors that initiate and control smoltification. According to Pye- 

 finch {116: 9): 



Smoltification is in some way connected with size, but the nature of this relationship is by no means direct. 

 ... It seems possible that rate of growth may be more important than the mere attainment of a critical length. 

 Reference has already been made to the observation that growth during the first year is an index of growth later 

 in life. Therefore, assuming that the internal changes which occur during smoltification are seasonal in their 

 incidence, a rapidly growing fish may have developed far enough for these changes to take place when it is only 

 a little more than a year old, whereas a fish which grows more slowly is not sufficiently well-developed for these 

 changes to take place then and so must wait until the following spring. 



Elson concluded that, as a general rule, parr that have reached or exceeded a 

 certain size towards the end of one growing season are likely to become smolts at the 

 next season of descent {43: 5). Those that have nearly but not quite reached a length 

 of 10 cm at the end of the summer will, if they grow fast, reach a much greater length, 

 say 14—16 cm, at the end of the following summer, and make big smolts. Those that 



