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add that the growth (weight) may vary considerably in different years and in 

 different localities. 



A good deal might be gained by studying the numbers of the different trade- 

 groups of fish brought to market. However for a deeper insight into these 

 questions a more exhaustive analysis would be required so that the numbers 

 of the different year-classes in relation to each other might be 

 ascertained. 



lyength-measurements can give this to a certain extent when the average rate 

 of growth is known. But it will, I think, appear sufficiently clearly from my 

 preceding remarks that this method has considerable limits and is frequently 

 open to much doubt, when we are dealing with so vast an extent of water as the 

 North Sea. Reliable results can alone be obtained if length-measurements are 

 combined with direct age-assessment, as for instance by means of testing 

 scales or otoliths. 



I have endeavoured to show that no insurmountable task is required for 

 obtaining a sufficiently representative material for showing the most important 

 problems concerning the occurrence of food-fishes like cod and haddock. In this 

 connection the catches of the market-trawlers would give especially valuable 

 information: if we could be furnished with the locality of capture and the number 

 of trawl-hours, — both given of course with requisite exactness —, and also if 

 the total catch of each single vessel, and not merely a part of it, could be 

 examined. 



