â9â KNUT DAHL. 



Among the fishes caught in the upper part of the river 

 during the same excursion (vide table VI, col. 2), and all of which 

 with a single exception, were sexually mature, only one was 

 below 30 cm. in length. 



The same fact will also be observed if the 3 last columns 

 in table VII are examined. They represent fishes caught, during 

 the breeding season, in the Battenfiord, the Gula and the Mandal 

 river. We also here notice the fact that there is no absolute 

 size limit at which sexual maturity is attained. At the same 

 time however it transpires, that the majority of trout spawn 

 when they have reached a length of 30 — 35 cm. 



If we examine those columns in the tables which are con- 

 structed upon the results of fishing experiments conducted during 

 the spawning time, it is obvious how exceedingly scarce the 

 mature fishes are, compared to the number of immature fishes 

 in the rivers during autumn. 



This fact however must not be considered as contain- 

 ing a correct representation of the real relation between the 

 numbers of mature and immature individuals in this species. 

 The fact, that sexually mature fishes rarely occur in the catches, 

 is to a large extent due to the hauls being effected in the main 

 courses of the rivers. These do not to any large extent seem 

 to afford spawning beds for the trout, the mature fishes pre- 

 ferring to enter side-rivulets and brooks of even quite incon- 

 siderable size and water-volume, localities where the use of seines 

 is excluded. Not only does this refer to the brooks and rivulets 

 joining the large watercourses, but nearly every small water- 

 course or even gutter, which directly joins our fiords or the open 

 sea, forms spawning places where trout breed in autumn. In 

 the immediate neighbourhood of the mouth of such small water- 

 courses one may during autumn always be sure to find large 

 trout, who only ascend the brook, when in the last stages of 

 maturity. 



