63 



concerned are displayed in figure 6. The plaice marked were on 

 the whole small and immature, as will be noted from the size of 

 the examples captured and returned to us. From a consideration 

 of those caught in the season of marking and in the following 

 winter and summer it is plain that little or no migration takes 

 place. There is a practical blank from November to January 

 each year, coinciding with that displayed by our trawling results 

 and the captures of the inshore fishermen, but their reappearance 

 in February and their persistence in territorial waters during the 

 summer is amply illustrated by the returns as displayed in the 

 chart. The migrants either returned to the bay where thsy were 

 marked or showed a slight tendendy to a southerly migration. 

 They are relatively sedentary, however, in the sense that the 

 seasonal migration is not to a great distance, as has already been 

 proved by an appeal to statistics and trawling experiments, and 

 the return is to the same feeding ground. 



During the first winter after marking, two were returned 

 which had migrated far to the north, and another was obtained 

 from Scottish waters in the following spring. Again, after the 

 lapse of more than a year, in the second winter of liberation, three 

 were returned to us from Aberdeen, Grimsby and Billingsgate 

 markets, but no information was obtained as to place of capture ; 

 it is evident that they must have migrated a considerable distance 

 to have been captured by other than local trawlers. Note must 

 be made of two females which in March had apparently not 

 migrated during a long period of liberation and of a size which 

 pointed to maturity. With this exception all the plaice which 

 had in the meantime reached mature size were recaptured after 

 about (or more) than two year's liberation far to the north, one 

 as far as the Moray Firth. This is so consistent that we are 

 justified in concluding that the plaice of the Northumberland 

 coast on approaching maturity, when they measure usually over 

 30 cm. (12 inches) migrate to join the spawning assemblages of 

 the Firth of Forth, of the Aberdeen Bank, and even of the Moray 

 Firth. The marking experiments made in Scottish waters have 

 proved that the mature plaice of the Forth region may migrate 

 far to the north, to the Moray Firth and still further north and west, 

 and the Moray Firth plaice even to the Atlantic, via the Pent land 

 Firth. The difference between the migrations of the immature 



