— 17 - 



B. HELLAND-HANSBN 



extremely instructive to know how the different proportions would have appeared, 

 had intense fishing not taken place. Now we have naturally no means of knowing 

 this: if for no other reason because we have not sufficient material to be 

 certain of the actual numbers of haddock existing in the North Sea, and because 

 we cannot therefore make any real comparison between them and quantity 

 caught. 



We have previously mentioned that the whole catch is not as a rule brought 

 to market. But since in our material we include all the individuals we have 

 caught, it is possible for us to give approximately the average relation 

 between marketable and unmarketable North Sea haddocks. If we 

 take existing sale-conditions in England and Scotland we will find that the 

 lowest limit for marketable may be put at about 21 cm.; though a few years ago 

 this limit was slightly higher (D'Arcy Thompson). 



Out of the total number, 49-4, we get on either side of 21 cm.: 



Unmarketable on an average 6-4 haddock per trawl-hour 

 Marketable — — 43-0 — — 



Total . . . 49-4 



or in other words roughly about one seventh of the average number 

 caught by the trawl in 1902 — 6 was unmarketable. 



As is well known the catches of haddock in Britain are sorted into 

 different market sizes, viz. Extra Large, L,arge, Medium, Small and Extra 

 Small — this latter being a new group of the last few years. According 

 to D'Arcy Thompson these groups correspond with the following average 

 lengths : 



Extra Large 60 cm. (half of them between 55 and 63 cm.) 



Large 40 - ( — — 38-43 cm.) 



Medium .... 35 — 



Small 30 — (half of them between 28 and 33 cm.) 



Extra Small 23 — 



D'Arcy Thompson informs us that the largest measurements for the Faeroes 

 were 83 cm., and for Iceland 89 cm. In the North Sea east of Scotland Extra 

 Large are rarely found, but about the Shetlands a few are caught up to 

 75—77 cm. 



In fig. 4 we have introduced vertical lines which practically correspond with 

 the limits between the different market groups. In reality there are no sharply 

 defined limits, since the groups overlap. However any error due to schematic 

 arrangement will be of but minor importance. It is easy to find by planimetry' 

 the approximate numbers of fish per hour for each one of these groups in the 

 average catch. 



' After testing by direct calculations this method of mensuration we have found the values to 

 be identical. 



