A STUDY ON TROUT AND YOUNG SALMON. 



are by many people considered young salmon. From several 

 localities such trout have been kindly forwarded to me for exa- 

 mination, by men, who either took an interest in getting 

 the species of these fishes determined, or acted in the belief 

 that they were sending me those sizes of young salmon, which 

 I had not been able to catch. 



I must admit, that the real cause of the trout returning to 

 the rivers during autumn, to me seems a mystery, and I can 

 offer no contribution towards a solution. 



Considering the numerous reports as to the trout being 

 injurious to ova and fry of salmon, I was led to suppose that 

 the trout in question perhaps ascended the rivers in order to 

 devour ova and fry. 



In order to test this supposition I have examined the con- 

 tents of large numbers of stomachs. In the trout, which has 

 spawned during autumn, the stomachs as a rule contained ova 

 and fry of salmon and trout, sometimes in not inconsiderable 

 quantities. The stomachs of the fat and shiny fishes, belonging 

 to the immigration group of autumn, did, during autumn 1898, 

 not contain ova or fry. On one accasion I examined ca. 100 

 stomachs, taken from the fishes which on May 5, 1899 were 

 caught at Forve bridge (vide table VI). Among these, only one 

 contained a small salmon fry; the rest were empty. Thus these 

 fishes would not seem to remain in the river on feeding pur- 

 poses. On the contrary it is highly probable that they eat next 

 to nothing. As I propose to show later on, they hardly grow 

 at all during winter. While ascending the river in autumn 

 they are fat and in splendid condition, they are in May, when 

 emigrating again, much more slender; they are in fact very lean; 

 the flesh is not so red; they do not fetch the same price, and 

 are also not so good eating as prime fish. 



As mentioned before, not all fishes belonging to this 

 group, ascend the rivers in autumn. Some remain in the sea 



Nyt Mag. i. Naturv. XXXXII, IV. 19 



