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take up the question: can we with our present knowledge form an opinion as to whether 

 there are any means by which the natural increase in the younger year-groups 

 can be influenced? 



Two different methods have been proposed for the attainment of this end; the one 

 to increase the stock of young fish by means of artificial fish culture, the other to 

 protect the smaller sizes by forbidding the sale of fish under a certain size, by 

 legally regulated size of mesh, or by the closure of certain areas. 



We shall briefly discuss here, how far the investigations made can contribute to throw 

 light upon each of these practical questions. 



4. The artificial culture, as is known, follows the method of rearing the 

 fertilized eggs until the larvse escape. It has proved impossible to keep them alive in 

 any very large quantities after this stage, and the various fish culture establishments can 

 therefore place in the sea only eggs in the last stage of development or the young larvae. 

 The Norwegian establishment, which produces the largest quantity of gadoid larvœ, sets 

 free yearly somewhere over 150 millions of these stages. When these young stages are 

 once set free into the sea, it is impossible to follow their further fate directly, especially 

 where eggs and larvœ of the same species were already present beforehand. On account 

 of their small size (some millimeters in length) and their delicate structure any notion of 

 marking experiments is here excluded. We can form no other picture of the further fate 

 of the liberated larvas than that which the plankton stages occurring in the sea offers in 

 general. There is nothing in fact which entitles us to believe, that the artificially reared 

 eggs or larvae would be differently situated as regards the surrounding medium from those 

 which have developed naturally. 



In judging of the importance and the fate of the plankton stages the following cir- 

 cumstances must especially be remembered: 



a. the natural conditions at the spawning places, 



b. the number of eggs and larvae naturally occurring on the spawning grounds, 



c. the passive wanderings (with the oceanic currents) of the plankton stages, 



d. the natural changes in the life of the younger stages of the gadoids and their 

 region of distribution. 



With regard to artificial culture in the open sea as a practical venture we may point 

 out the following: 



a. When each species seeks out its definite spawning places and its eggs and larvae 

 are only found under definite, specific natural conditions, we must accept it as a rule, 

 that liberation of larvae at other places with physical conditions of a different kind can 

 scarcely be favourable to the fate of these. Experiments have also sufficiently shown 

 the great influence of the physical conditions on the development. 



b. When the eggs and larvae are present on the spawning grounds in such quantities 

 as have been demonstrated by the quantitative investigations, the numbers produced by 



