— 19 



B. HELLAND-HANSEN 



numbers were under and only 40% were over the limit for maturity. 

 Of marketable fish (over 21 cm.) rather more than half, or about 54%, were under 

 the limit for maturity. 



3) Variations in the composition of the average catches 



In figs. 5 — 8 can be seen the average size-distribution in the dif- 

 ferent years from 1903 — 1906 (inclusive) both within the several groups 

 of areas and also within the whole North Sea so far as examined. 

 The curves are drawn exactly in the same way as those in fig. 4, except that 

 owing to the paucity of large haddocks we have left out that part of them which 

 goes beyond 50 cm. The figures show the size-distribution in the same average 

 catches as were given in the tables on page 13. 



It is quite clear from each one of these four figtires that as we leave the 

 shallower southerly areas and go northwards the aggregate average numbers 

 increase. Everywhere we get least fish within the Southerly Areas and most 

 within the Northerly Areas, in accordance with the values previously given. These 

 differences in numbers are met with in the lower market-groups. Extra Smalls, 

 Smalls and Mediums. But even in the Mediums they become less pronounced, and 

 when we come to Large the relations are sometimes reversed. Thus in the 

 average catches for 1904 and for 1905 there were just as many Large in the 

 Mid group as in the Northerly group of areas. It is clearly shown too by 

 the original material that there were more Extra Large per trawl-hour 

 on an average in the Southerly group of areas than there were 

 in the Northerly group. The tables accordingly give the following number 

 of individuals per 100 trawl-hours, taking the average of all the years. The area 

 I is here included in the mid group of areas and not in the northern one as was 

 done before. 



Number per 100 trawl-hours 



cm. 50—54 55—59 60 and over 



Northerly group of areas 34 8 2 



Mid — — 20 6 6 



Southerly — — 17 15 23 



It can be easily seen from the figures how in the Northerly group of areas 

 Extra Smalls and Smalls constituted the bulk in all four years. Within these 

 areas however Mediums sometimes (as in 1904) contributed a considerable portion 

 of the whole catch: while the number of Large in all the years was small in 

 comparison to the total catch, even though in some years (1903 and 1906) the 

 numbers were in actual fact quite considerable. Within the Mid group of areas 

 the Mediums in 1904 exceeded all the other sizes: but in this group too in the 

 other years Extra Smalls and Smalls were easily in the majority. Here and to 

 a certain extent still more so in the Southerly areas there is a greater proportion 

 between the relative numbers of the Large group and the smaller market groups 

 than we get in the Northerly areas. Thus as a rule the number of Extra Smalls 

 and Smalls preponderates within each of the groups of areas. But this pre- 



