— 9 — KNUT HAUL 



We thus uuulil nut seu llic possibility of iiicreasin;? the lisli stock of such a small 

 area by means of liberating: larvae which for a long tinio wore tlrifling. 



The ((uostion of the means of locally infhionciiig \\\e (Isli supply would, according 

 to our views, be to attempt to rear the larvae beyond the di'iftiiig sta^e and also to 

 investigate the occurrence of such young in nature. 



For the present, however, we thought it just to consider the fish stock of a considerable 

 stretch of coast as belonging to or common to the whole of the area. The old fish 

 could be proved to migrate and the eggs and pelagic stages of the young fish would 

 on account of tiieir dependence on currents belong to the whole area. 



The correctness of these views has been criticised by those concerned in the hatching. 

 In order to gain more knowledge, special investigations and experiinents have been 

 made in some of the Ijords of Southern Norway during the years 1903^ — 1905. 



Some of these investigations have been made by me and the manager of the 

 Flodevigen hatchery in common. Some have been carried out by me alone. 



The investigations in common have comprised: 



I) The collection of statistics on the occurrence of littoral cod fry in the Sondeled and 

 Helle fiords in connection with the liberating of cod larvae from the hatchery. The 

 statistics have been collected by means of repeated hauls with a seine in the same 

 localities at different times and by counting the number of littoral fry obtained. 

 II) Experiments as to the relation of cod eggs and larvae to density and temperatures 

 in sea water. 

 My investigations have comprised: 



1) A study of the hydrography of the Skagerrack fjords especially the Sondeled Fjord. 



2) The occurrence of fish eggs, larvae and young. 



3) The growth and general biology of the cod. 



4) Marking experiments on cod. 



5) Collection of statistics on the cod fisheries around Ris0r. 



6) Statistics showing the occurrence of littoral cod fry in the Sandnes and Stole Fjords 

 (see chart pag. 10), where no larvae have been liberated, and also in the Christiania 

 Fjord. The statistics have been obtained by a systematic repetition of certain hauls 

 with a fme-meshed seine, and by counting the fry caught. 



The results of these investigations have been published in detail in "Aarsberetning 

 vedkommende Norges Fiskerier", 1. hefte 1906 ^ 



As regards the details the reader is referred to that publication. 



In what follows I will endeavour by means of this material and other information 

 in our possession to set forth the main points which apply to the hatching problem in 

 the fjords of Southern Norway. 



' ünders0gelser over nytten af torskeudklœkning i Östlandske fjorde: 



1) Betaenkning afgiven af Kndt Dahl. 



2) — — - G. M. Dannbvig. , 



3) Bilag 1." Undersngelser og forsag foret, i fœllesskab af K. D. og G. M. D. 



4) — 2. — - — — af K. D. 



