— 94 — 



by surrounding the cod-end of the trawl by flne-meshed netting gave the same result; 

 the small fish passed through the trawl and were taken in the outer fine-meshed net. 

 From 25 cm. the numbers of the specimens rapidly decreased, after 40 cm. more slowly_ 

 The curve shows the following relative numbers: 



at the size . . 20 25 30 35 40 45 50 55 and 60 cm. 

 occurred ... 80 175 110 60 20 ^ 5 3 » 1 specimens 



Thus for every haddock at 60 cm. in length in the hauls there were about 200 at 

 25, 50 at 35, and almost 10 at 45 cm. 



The weight curve is very different from the number curve. Its maximum is at 30, 

 that of the latter already at 24 cm. The specimens under 32 cm. constitute by weight 

 almo.st the half of the catches. The curve also shows that, although but few specimens 

 of the larger sizes are present, yet these constitute a not inconsiderable part of the weight. 

 It is also very interesting to examine the different parts of the curves more closely. For 

 this purpose we may mark off on the curves the limits which the fish trade in Scotland 

 employ to distinguish the different market classes of the haddock. These 

 market classes, which together constitute the marketable fish in contrast to the too small 

 unmarketable fish, are as follows: "extra small", "small", "medium", "large" and "extra 

 large". The accompanying table shows the limits for the sizes of these classes (in cen- 

 timeters) and the average numbers and weights which fall to each class per 

 hour of fishing according to the curves (fig. 27). 



Number Weight 



Class Limits in cm, Specimens o/o Kg. °/o 



Extra small 21 — 27 19-9 40 2.7 22 



Small 27 — 32.5 13.1 27 3.2 27 



Medium 32.5 — 37.5 6.6 13 2.5 21 



Large 37-5— 5° 3-o 6 2'5 =" 



Extra large 50—60 0.4 1 0.7 6 



Total marketable 21 — 60 43.0 87 11.6 97 



Unmarketable under 21 6.4 13 0.3 3 



Total... 15 — 60 49.4 100 1 1.9 100 



If we now consider the numbers, the fact is very obvious that the classes "extra 

 small" and "unmarketable", thus the classes up to 27 cm. in length, contain more spec- 

 imens than all the other classes. Even excluding the "unmarketable", the class "extra 

 small" is alone almost, as numerous as all the other classes of the "marketable" fish, 

 and the class "small" is also more numerous than the three largest classes together. 

 The "large" constitutes only Vis^h of the whole number and the "extra large" not 

 even 1 %. 



The weight on the other hand is evenly distributed between the classes "extra 

 small", "small", "medium" and "large", but the classes "extra large" and "unmarketable" 

 have a much smaller weight. On comparing number and weight we have the following 

 important relations: The class "small" has the same percentage under number and weight; 

 it represents the average in both cases. On an average all the haddock weigh 0.23 kg., 

 and this weight corresponds to a length of about 30 cm. The classes "large" and 



