— 22 — 



These curves are not similar to the general curve in fig. 4. There is a 

 prominent size-group in all the four curves for the whole area investigated, 

 though it occupies different positions. Beside the big group which centres 

 round 20 cm. the curve for 1905, e. g., shows also a not particularly 

 prominent group centring round 30 — 35 cm. Now in a curve denoting the 

 whole year one would not find several groups if the various ages were re- 

 presented in an evenly decreasing series. Two groups separated by a depression 

 point accordingly to the fact that one or more year-classes are not fully 

 represented at the point where the depression occurs, or else that one or 

 more of the year-classes is abnormally over-represented at the sides of the 

 depression. 



By means of the comparison in fig. 29 we can now perceive an advance from 

 year to year of the situation of the groups. 



Thus in 1903 the greatest number is to be found in a big group centring 

 round 30 cm., the preponderance being within the group Smalls. In 1904 

 we find a corresponding group further to the right whose average length 

 is some centimeters more: part of this size-group belongs to the Smalls, 

 though the biggest quantity are Mediums. We can still trace the same 

 group in 1905, but later on the group is lost sight of. In 1905 we find 

 a group centring round 20 cm. (Extra Smalls). The corresponding group 

 centres round 25 cm. in the following year and still consists for the most 

 part of Extra Smalls. Quite a considerable quantity however come within 

 the limits for Smalls. In this way we can follow the different market- 

 groups and watch their development throughout a prolonged 

 period. 



And in this case it is remarkable that Extra Smalls scarcely occur in 

 1903 and 1904, while as an apparent consequence there are few Smalls in 

 1905 and in 1906 few Medium. But in 1905 we find a large amount of 

 small Unmarketables , and in 1906 we meet with a strongly developed 

 group of Extra Smalls. These curves correspond with the tables previously 

 given and clearly confirm the conclusion we arrived at, that the 1902 

 year-class and the 1903 year-class more especially occurred 

 sparsely in the succeeding years throughout all that portion 

 of the North Sea which was investigated, whereas afterwards a 

 relatively large quantity of haddock born in 1904 were found. 

 Similarly the big group in 1903 must be ascribed to year-classes dating from 

 1900 or there about, which year contributed quantities of individuals to the 

 haddock supply of the North Sea. 



It follows undoubtedly from these representations that there were 

 great variations from year to year in the occurrence of 

 the various market-sizes and in the proportion they bore to 

 the catches. The following tables exhibit these proportions in ciphers; 

 the first shows the numerical distribution of individuals in the different 

 years. 



