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Condition of nourishment. Quantity of food available in a selected area. 



England. 10) The bottom fauna of an area on the Dogger has been invest- 

 igated by means of the Petersen grab. (See also under Plaice Committee). Many 

 stomachs have been examined and the contents identified. Special gear is being 

 evolved to take quantitative hauls of the larger freely moving animals forming 

 part of the cod's dietary. 



Scotland.. 10) In a large number of experiments, the stomach contents of 

 the haddocks caught have been determined on the research steamer, but in addition 

 a fair number of samples of stomachs from various size groups have been preserved 

 and brought to the Laboratory. At the same time, similar methods have been 

 adopted with regard to possibly competing species found on the same grounds. 

 The dredge and small trawl have been used to ascertain the quantity and quality 

 of food available on the various grounds. 



11. Study of methods of age determination, in conjunction if possible with tank 

 experiments. 



England. 11) A beginning has been made with the study of cod scales in 

 conjunction with the Petersen method of age-determination. 



Scotland. 11) Attention has been devoted to the study of methods of age 

 determination in view of its cardinal importance. Scales from representative samples 

 have, as far as possible, been taken periodically from each area for age determination. 

 The early year groups have been easily defined, so that a relatively small pro- 

 portion of fish under 30 cm now require to be scaled. Work is now being concen- 

 trated upon defining the older groups whose representatives are all scaled for 

 examination. A batch of Norwegian scales has been worked through and the study 

 of racial characteristics is being developed. 



12. Determination of size and age at first maturity, particularly in cod. 



England. 12) Observations on maturity were carried out at sea both on 

 the Research Ship and on commercial vessels, and on shore; a naturalist and a 

 measurer being detailed for service on the North East coast for this purpose. 



Scotland. 12) All cod material is handed over to the English Department. 



Denmark. 12) Some age determinations of cod have been made. 



13. Study of the migrations of cod and haddock including marking experiments 

 with mature cod. 



Denmark. 13) The pre-war marking experiments with cod in the North Sea, 

 Skagerak, Kattegat and the Belts have been worked out. 



England. 13) Cod were marked and liberated from the "George Bligh", 

 and also from a motor coble on the Yorkshire coast. They were measured and 

 marked either below the dorsal fin or on the operculum, and scales were taken 



