— 39 — KNUT DAHL 



of hatching work, and tliat it will bo necessary to attempt a more serious inquiry into 

 the economic side of the question. 



The discouraging results in regard lo I ho prospects of the present cod hatching 

 gained by our investigations do not favour the assumption, that results of great conse- 

 quence will be attained, if we restrict the hatching work Lo a mere protection of the 

 eggs during the short lime of incubation. The logical consequence of the present 

 experience should be to attempt some technical advance in the treatment of the larvae. 

 Only when possessing the means of cheaply and plentifully producing fry in the bottom 

 stage will the fish hatcher occupy a position free from those serious doubts, which our 

 present experience of the conditions of pelagic larvae justly call forth. 



The problem would then be reduced to a question if a lack of fry really occurs 

 in nature and in this case whether such a lack might not with greater advantage be 

 remedied by means of a transplantation of fry from localities which are rich in fry '. 



These small Norwegian fjords are, as I have mentioned, perhaps the smallest waters 

 in which an extensive sea fish culture may be supposed to operate. Still our results 

 plainly show the contrast between what has been achieved to date by sea fish hatching 

 and the successful fresh water-culture from which the ideas of the prospects of sea fish 

 hatching have been taken. 



'e 



2. The large waters 



As regards the feasibility of the present hatching for large waters i. e. the coast, 

 the open bays and oceans, the results in our possession render the question very clear. 

 For these waters it is sufficient to refer to the clear examples, given in this Report, of 

 the great difference between the extent of the spawning areas peculiar to the different 

 species and the areas in which the fry is to be found in different stages, nor must we 

 forget the drift of pelagic eggs and fry which has been proved to occur over great 

 distances. 



On the one hand then it is clear, that the liberation of larvae would be incapable 

 of locally influencing the fish supply. On the other hand hatching operations on a 

 scale, that would be capable of influencing the enormous quantities of drifting fry 

 which the open waters of Northern Europe have been proved to contain , are from a 

 technical as well as from an economical point of view outside practical possibilities. 



• As is well known this latter method has been advocated by Dr. G. G. Joh. Petersen in regard to plaice 

 and has also been employed by him in Danish waters (the Limfjord) with very promising results. 



