58 THE AGE AND GKOWTH OF SALMON AND TKOUT. 



Remembering the fact that these samples from Utskarpen have been 

 taken two months later in the season than the samples from the Trondhjem- 

 fjord, and also in a different year, we are entitled to say that the average 

 lengths are in fairly close agreement. Consequently if the growth is so 

 similar in districts so remote from one another, we are justified in assuming 

 that these values are fairly characteristic, at any rate for the northern parts of 

 the country. This assumption, moreover, is confirmed by various small 

 samples which I have occasionally had the opportunity of examining. 



How matters stand in the south I have not yet sufficient material to 

 say, though a few samples from the Os river near Bergen and from the 

 S0ndeled river at Ris0r show no essential difference from what I have 

 described in the case of the northern streams. 



With regard to maturity in sea trout, both prior to and subsequent to 

 migration, our sample from the Trondhjem-f jord unfortunately does not tell us 

 anything, since we were unable to make the necessary examination of the fish. 



I have, however, obtained valuable information from a large sample 

 obtained from Utskarpen in Ranen. 



In Tables XVIII. and XIX., I have made an analysis of the samples that 

 were taken between 1st and 10th September, 1907, partly in the Dalos 

 river at Utskarpen and partly in the sea at the mouth of the stream. 



Table XVIII. includes all the fish which were caught in the Dalos river, 

 and which, both by their appearance and from the structure of their scales, 

 may be said never to have quitted it. 



The table shows us that it is only exceptionally that the river contains 

 fish which are more than six winters old, and which have not been to 

 the sea. Consequently we are dealing here practically solely with those 

 age-classes which characterise the sea trout smolts. Their size, too, as 

 we notice, varies between 10 cm. and 25 cm., exactly what was found to 

 be the case with the migrating sea trout in the Trondhjem-fjord. 



By means of the table we can make out the following summary of 

 sex and maturity in relation to age. 



