ON SALMON. 



39 



and which spawn for the first time in their third and fourth winter, very 

 seldom reappear in the form of fish with a spawning mark. 



This evidently points to the fact that few of the older fish survive 

 more than one spawning. 



With reference to the duration of time which elapses before a fish 

 which has once spawned again returns to spawn, the study of the scales 

 with spawning marks affords useful information. With certain reservations 

 one can read from the scales how many summers and winters have elapsed 

 since spawning occurred. To illustrate this I have drawn up the following 

 table, which shows the length of absence after the first spawning. These 

 figures must not be regarded as absolutely correct, but they are sufficiently 

 so for comparative purposes : 



19081909. 



Here, too, we seem to be able to trace a difference between the northern 

 and southern districts as regards the variation in the fish's absence after 

 the first spawning. 



Let us now sum up briefly what we have learnt from our investigations 

 as to the age of the salmon after migration. 



Everywhere throughout the country where our investigations have 

 been conducted we find that our material is composed as follows : 



By far the largest majority consists of fish which have never spawned 

 and which have remained in the sea from one to three and exceptionally 

 four winters, and which are therefore in their second to their fifth summer 

 after migration. 



These fish spawn in the second to the fifth winter after migration, and 

 apparently only a portion of them chiefly composed of the younger fish 

 survive the spawning journey and the actual spawning. This little band of 

 survivors returns again to the sea, and some of them after the lapse of one 

 year, others after two years, and very few after three years interval, return 

 to spawn for the second time. Only an infinitesimal portion of these, 

 about one in a 1,000, have shown that they have returned to spawn for the 

 third time. 



