518 EEPORT OF COMMISSIONER OF FISH AND FISHERIES. 



between rivals is probable. If one could secure for the ascending fishes 

 an easy passage over the intercepting cataracts and dams, then certainly 

 very few fish would die from getting sawdust in their gills. 



That young salmon bred from a race of salmon which has its own 

 river, when they are set free in a strange river and one which is in an 

 unusual degree polluted by sawdust, will not be prevented by this cir- 

 cumstance from returning to this last-named stream after their wander- 

 ing in the sea, one had a convincing illustration in the great exiieriment 

 instituted last year by Director A. Hansen. In olden times the salmon- 

 shoal which had its spawning-place in Soli River could ascend to it 

 through the then passable Soli cataract, but when they, for the sake of 

 the increased mill-business, erected above the cataract a dam so high 

 that the salmon could not ascend to their spawning-grounds, this salmon 

 shoal gradually died out entirely. With the consent of the mill-owners 

 Mr. Hansen in 1868 constructed a hatching-apparatus, which in Novem- 

 ber of the same year was supplied with impregnated salmon-eggs trans- 

 ported from the fishery at Hellefos. On St. John's Mght, 18G9, the 

 young arising therefrom were liberated from the aijparatus into the 

 river, partly above and partly below the dam. Last summer a portion 

 of the planting returned as young salmon, and according to experience 

 gained elsewhere we should wait for the great body of them until the 

 coming summer ; because the greatest portion appear to pass the first 

 two years of their lives in the rivers and two years in the sea. 



In case one could aid the advance of the salmon around the Sarp cata- 

 ract or Soli cataract — and perhaps in this way a few less important 

 water-falls — and in connection therewith furnish the Glommen with arti- 

 ficially hatched young, one may now be fully assured that the abun- 

 dance of sawdust which incumbers both branches of the Glommen, 

 which again unite between Sarpsborg and Fredrikstad, will not prevent 

 the salmon from going up to the falls, where they will then probably 

 soon find access to a rightly constructed salmon-ladder, which would 

 help them up to a portion of the great river freer from sawdust. The 

 result of Mr. Hansen's experiment should therefore be a good support 

 for the watchful action of the management of our association, which will 

 in due time be communicated to the members. 



