308 KNUT DAHL. 



About 500 metres from the mouth of the river was a h'ttle 

 waterfall which prevented the further ascent of sea-trout. Of 

 this latter form fullgrown individuals in no small number occurred 

 in this lower stretch of the river mingled with trout of the above- 

 mentioned sizes, right down to the river mouth. Undoubtedly 

 some of the fishes in the above representation, which are not 

 sexually mature, are the brood of the sea-trout, which in time 

 would emigrate and develop in the sea. As will be observed 

 these facts are very complicated. However, a prohibition against 

 killing trout under 20 cm. in the lower part of this river, where 

 sea-trout run, will deprive the people living on the surrounding 

 farms of the whole catch of freshwater-trout. 



Certainly this catching of smaller trout cannot be termed 

 specially important, except as offering chances for sport fishing 

 or fishing for food; but it will be easily understood that a pro- 

 hibition against killing fish under 20 cm. will be difficult to 

 obey. 



Such rivers are plentiful in our country, even to such a 

 degree, that most rivulets or brooks running into the sea may 

 probably be said to possess similar conditions. 



Provided it should be deemed necessary to secure the pro- 

 tection of young trout by means of a prohibition against kill- 

 ing such fish, consideration of the conditions peculiar to these 

 rivers would prompt us to fix the size limit as low as 15 cm. 

 Smaller fish would be of no value for food or sporting purposes. 



If the authorities however would be satisfied with protect- 

 ing these young fish by means of a regulation prohibiting the 

 sale of sea-trout under 20 cm. in length., the interests of these 

 rivers presumably would be served. However in forming such 

 a regulation it must be strongly kept in mind, that such a 

 provision, to he effective, must also refer to freshwater-trout. 

 As I have before mentioned, it is generally quite easy to distin- 

 guish sea-trout and freshwater-trout, excepting the young and 

 the sexually mature fishes. Now the sizes below 20 cm. are just 



