- 68 — 



Denmark. 1) Systematic fishing experiments have been carried out along 

 the Danish coast in order to procure informations as to the frequency of young 

 plaice as compared with that in the pre-war years. 



2) Age determinations of plaice from the North Sea, Skagerak and Baltic 

 waters have been carried out. 



3) Measurements of plaice landed by Danish fishing vessels from the western 

 Baltic have been undertaken. 



4) Racial studies of plaice from the Baltic waters have been undertaken. 



5) Collection of plaice eggs with Hensen's egg-net have been carried out 

 in the Belt Sea. 



6) Marking experiments with plaice from the western Baltic have been 

 undertaken. 



7) An experiment with transplantation of 6000 plaice from the North Sea 

 to the Lesser Belt have been carried out. 600 specimens were marked. 



England. New work on the plaice has been limited to the research on bottom 

 fauna described below, but measuring work at sea has been continued on a similar 

 scale to last year. 



Progress has been made with writing up the results of the 1920 — 21 intensive 

 study of the plaice. A report on the age and maturity determinations is practically 

 complete, and much has been done on the commercial statistics and measure- 

 ments at sea. A report on the plaice eggs collected during the spawning season 

 1913 — 1914 has been submitted for publication and the data obtained during the 

 season 1920 — 21 have been tabulated. The egg production has been calculated 

 by the methods used for 1918 — 14 data, and it is thus possible to compare the 

 egg production of these two seasons. For the period December 18th to February 

 13th, the egg production of 1920 — 21 was very nearly twice as great as in 1913 — 14. 

 This is without allowance for temperature, which will make the difference between 

 the index numbers still greater. 



The otoliths of 1920 plaice caught in a continuous hne of hauls with the 

 otter trawl, extending from the Leman ground to within a short distance of the 

 south end of Texel Island, were collected in May 1922 for comparison with similar 

 collections made along the same line in May 1906 and May 1920. The otoliths have 

 been stored for future examination. 



Examination of the measurements made to March 1922 has been commenced 

 with a view to comparison with the years dealt with in the Provisional Report. 

 An increase of small plaice is very evident during the summer months of 1921. 

 A small amount of material is available for the comparison of the size composition 

 of the catch of trawl and seine, but at present is inadequate for a firm conclusion: 

 there are, however, definite indications that the smaller fish escape the seine. 



In a general sense the catch per 100 hours fishing during 1921 is markedly 



