_ 37 — JOH. HJORT AND C. G. JOH. PETEKSBN 



zostera, though not so numerous as the I-group. With exception of some few places 

 with resting water, extremely few specimens of the 0-group were taken on the bottom 

 throughout the entire summer. The 0-gronp was eagerly sought for through the whole of 

 autumn in Nyborg Fjord on the Great Belt, but found extremely rarely. Even in December, 

 only a few specimens under 19 cm. were observed. The steamer "Thor" investigated all 

 depths in the Kattegat with trawl and sand-eel net, both the middle and the bottom layers, 

 but could not find any mentionable quantity of the 0-group. 



From all these investigations on the natural history of the cod during the first year of 

 life, we can conclude that the distribution of the first bottom-stages is dependent above all on 

 the influence of the oceanic currents during the free, floating stage. According to the change 

 of these currents in the different geographical regions and in different years, the distribution 

 of the small yoiing cod will also change. It is clear, that all practical considerations of at 

 some time influencing the stock of the cod and of fishes related to it, must reckon with these 

 important conclusions. 



As said above, experiments have been made in Norway in accordance with these experiences. 

 Pelagic cod larvae are being set out in some fjords, but not in others as nearly as possible 

 similar. The quantities of the bottom-stages in both are to be compared later by exact inves- 

 tigations. 



In this way, we hope after some years to win trustwortly material for judging the question, 

 whether the setting out of cod larvae is of use or not. 



3. Rate of growth, migrations and tlie fisheries of the cod 



In all the countries which have joined our common investigations, a number of measurements 

 of cod have been made in the course of the last two years, partly at the fishing-ports, partly 

 on board the research steamers. A rich material of measurements, relating to the rate of growth 

 of the cod in accordance with the method described in Section II, has tlius been collected both 

 from the Norwegian Sea and from the North Sea. 



From these it appears chiefly, that its growth is very different in different regions. We 

 saw above, in the section on the spawning of the cod, that the first spawning group had an 

 average size of ca. 70 cm. in northern Norway whilst tlie corresponding size at Iceland was 

 70 to 80 cm. Similar differences appear m the present material, perhaps in all groups. 



For this reason, it will only be possible to display the results of the measurements made 

 when they have all undergone a thorough comparative examination, which up to the present 

 has only been done in part. As a description of the results, moreover, would require a minute 

 treatment of the matter, we must restrict ourselves here to a reference to Section II where the 

 conditions at Iceland have been more closely exemplified. 



The information regarding the place of capture, obtained at the same time as the measure- 

 ments, gives an insight also of the habitats of the various size-groups during the different 

 periods of the year, from which again, conclusion may be drawn regarding the migrations of 

 the fishes. 



At Iceland, the occurrence of the cod at all depths from — 630 m. could be ascertained, 

 though ordinarily in small quantities only, deeper than 270 m. 



