ON SALMON. 



51 



importance compared with those in the west and north. If we regard 

 the relative importance of the yield of the river fishing in proportion to the 

 whole catch as an indication of the intensity of spawning, it would seem that 

 relatively there is far more spawning in the south, but we also find that 

 spawning results in a relatively far larger total yield as we proceed 

 northwards. 



18801906. 



It is impossible without further information to say whether it is a fact 

 that some of the fish which are hatched in the south go northwards when 

 older, or whether it is that the southern fish return to spawn when they are 

 younger and smaller, whereas the northern fish only return to spawn when 

 they are older and heavier (and in this way each individual smolt would 

 eventually give a larger result in weight). For the present this must remain 

 an open question. It is most likely, after what we have seen, that both 

 causes are operative, but, in any case, this remarkable geographic 

 distribution of yield in our salmon fisheries has had new light throw 

 upon it, and that, too, from a source which has not hitherto been 

 available. 



(e.) Distribution of the Year-Classes. 



As I have stated previously, and as will be seen on examination of the 

 tables in the Appendix, the smolts are not all of the same age, nor have 

 they all spent an equal time in the sea when they return for the first time 

 to spawn. 



Some return sooner, others later, quite independently of the age at 

 migration. 



This circumstance is a matter of great importance to the general stock 

 of salmon, as we shall see later. 



In the following table I have arranged all the fish I have investigated 

 from Christiansand, Trondhjem and East Finmarken in 1908 and 1909, 

 according to district and year of birth. 



When we examine the table carefully it is evident that the fish which 

 we have to deal with in our fisheries in any one season, and of which the 

 majority are on their way to the rivers to spawn for the first time* are born 



* Fish with spawning marks are also included, but as was seen before, they are only 

 a very small proportion 2 to 10 % of the total catch. 



42 



