— 1-24 — 

 , 1. The number of the winter rings shows.how many years, old _the.-CO.d; is. 



2. If the scales of the cod are investigated at all seasons, they' show at what tinie 

 the winter concentration of the elementary rings begins, in other words, when a stoppage 

 in the growth of the fish takes place in any definite region; they, correspond on the 

 whole to its rhythmical growth in the region concerned. 



3. By comparing the growth in the different regions we can investigate the condi- 

 tions of growth of any species over the entire region of its distribution. The scale in- 

 vestigations thus yield us not only an insight into the age of the gadoids, they give us 

 also a deeper understanding on the whole of the conditions of life of these species. 



We may now consider what the scale investigations can tell us for certain regarding 

 the growth of the cod in the different localities and then compare the different parts of 

 the region over which the species is distributed with one another. 



North Sea. The growth in the North Sea is more regular and more rapid 

 than in any other of the regions investigated. In the first year the cod may reach a 

 length of 20 cm., on an average 14 cm. according to Heincke. In" agreement \yith this 

 the scales of the first year are very large, having up to 30 elementary rings. It is 

 remarkable that some few (about 2%) smaller individuals occur at times with only 5-6 

 rings. The growth during the following years is so regular, that the determination ' of 

 the age is more difficult here than in any other of the regions investigated ; it is only in 

 the specimens over 60 cm. in length that the winter rings are well-marked, presumably 

 because the spawning has then begun. 



The rate of growth according to Damas is in the first year 12 — 15 cm., in the second 

 year 12 — 15 cm., and from the 3rd to the 5th year 8—10 cm. annually. 



' In the Norwegian Skager Rak fjords the growth during the first year is also, 

 very good. The o-group shows the following average lengths: 



In June .... 3—4 cm. 



- July .... 5 — . 



- August. . . 6 — 



- September .9 — 



- December .13 — 



Some isolated specimens of the o-group of 22 cm. in length were found in No- 

 vember. In autumn, however, as is shown by Damas' and Dahl's investigations, a new, 

 smaller o-group appears which is quite distinct from the older. Its occurrence must be 

 due either to a late spawning or to the circumstance that these fish have remained in 

 places where they have only grown slowly. The further growth is influenced by the 

 fact, that in the strand-region of the Skager Rak the cod becomes mature at a much 

 small&r size than in the North Sea. Whilst the limit for the inception of maturity, in the 

 North Sea may be placed at 60 cm., mature cod of, only 22 cm. have been found in 

 the Skager Rak fjords; most were mature at 30—40 cm. in length. The age deter- 



