REPORT OF THE COUNCIL. 425 



populations on the more important grounds, as well as upon the more 

 important seasonal changes in such characteristics ; and a series of 

 summary reports is in course of preparation for submission to H.M. 

 Government during the current year as each is completed. 



Fish Measured. — As a rough indication of the material obtained 

 upon these voyages, it may be stated that more than 88,000 measure- 

 ments of fish, representative of the total catch on almost every occa- 

 sion, were made and recorded at sea during the past year, in addition 

 to other work. 



Nearly 300,000 fishes have been measured in this way since the 



commencement of the investigations, as shown in detail in the following 



table : — 



Plaice. Haddock. Others. Totals. 



1902-5. Voyages I-LAa . . 65,509 15,950 128,775 ... 210,234 



1905-6. „ LVII-LXXV 24,954 10,755 52,885 ... 88,594 



Totals 90,463 26,705 181,660 ... 298,828 



Marking Experiments. — During the past year 2042 marked plaice 

 have been set free. 



To the end of June, 1905, 5115 marked plaice had been liberated, of 

 which 1224 have since been recaptured, yielding a percentage of 23*9 

 per cent. 



More than 7000 marked plaice have thus been set free up to date. 



The data yielded by these experiments are now sufficiently numerous 

 to yield valuable indications of the main differences in the annual 

 rate of growth of plaice in various parts of the English area. In certain 

 areas they also show the progressive rate of growth from month to 

 month. In addition to these results the experiments have thrown a 

 continually increasing light on the seasonal migrations of the fish, the 

 intensity of fishing in different areas, and upon differences in the rate 

 of growth and habits of the two sexes ; they add thus to our knowledge 

 of the life history of this species in matters of considerable importance. 



Transplantation experiments have been carried out during the spring 

 months of 1905 and 1906 in order to check the results already reported 

 as having been obtained during 1904. 



The results of these experiments indicate that the rate of growth 

 on the Dogger Bank is always markedly higher than on the coastal 

 grounds south of 54° N. lat., though subject to variation in actual 

 amount from year to year. Experiments have been carried out during 

 the present year in order to determine whether this urea of rapid 



