106 REPORT OF THE COUNCIL. 



In the Southern Grounds it is indeed apparent that the females 

 move northwards at an earlier date than the males, the females pre- 

 dominating among the fish of mature size marked near Smith's Knoll, 

 off the Norfolk coast, while the males are in excess in marking experi- 

 ments farther south. 



Experiments on the Eastern Grounds show the annual movements 

 offshore in the summer and inshore in the spring which have already 

 been remarked by many investigators. Practically none of the fish 

 recaptured, however, were of mature size. It is hoped that the ex- 

 periments of 1909 will cast some light on the movements of mature 

 plaice in this locality. 



An observation involving deductions of considerable importance has 

 been made on the fish trawled for marking. The fish are found to 

 differ as to the appearance of the eyes, which are in some cases 

 markedly bright, in others dull. In four experiments particulars of 

 the recoveries of the fish so distinguished have shown that the plaice 

 with bright eyes were recaptured in far greater proportion than the 

 rest. The percentage of the former recovered ranged from 49-54, that 

 of the latter during the same period from 23-34. The eyes therefore 

 would appear to aftbrd a test of the condition of the fish. The high 

 proportion captured in the case of the bright- eyed plaice was fully 

 maintained in two other cases in which only fish of that kind were 

 marked. 



The many experiments in which no distinction was made between 

 these classes of plaice uniformly show a lower percentage of recaptures. 

 Thus in forty-nine experiments made during spring in the course of 

 the International Investigations, the percentage recovered only ex- 

 ceeded 40 per cent in five cases, whereas in an experiment made in a 

 worse fishing season 50 per cent of the bright-eyed plaice were retaken 

 in a less number of years. These facts suggest that previous experi- 

 ments of the intensity of fishing drawn from marking experiments, 

 high though they undoubtedly seemed, were too low. The percentages 

 of recoveries during a year met with among these selected bright- 

 eyed plaice somewhat recall indeed the proportions of Mr. Bidder's 

 bottom-drift bottles returned from fishing vessels. 



Eggs and Larvae of Fishes. — The cruise of the Huxley in June, 

 1909, yielded some important additions to our knowledge of the eggs 

 of many fishes. The eggs occurring in the greatest quantities were 

 those of Mackerel, Sprat, Horse-Mackerel, and Solenette, and the 

 cruise may be said to have considerably advanced our knowledge of the 

 spawning of these species of fish in the Flemish Bight. The great 

 numbers of the eggs of these species which were taken indicate that 



