188 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



into the Estuaries of the Mersey and Dee to the South. 

 The migration path most commonly followed is, however, 

 that leading towards Red Wharf Bay to the West, and 

 most of the large and medium-sized plaice which inhabit 

 the Nelson Buoy grounds, and survive the summer and 

 autumn fisheries there doubtless form part of the shoals 

 which appear off the coasts of Anglesey and Carnarvon 

 during the last months of the year. The plaice-marking 

 experiments show this very clearly — even the meagre 

 records of single experiments, such as those of last year, 

 summarised in the present Report — show it, and the 

 evidence becomes convincing when we deal with groups 

 of experiments carried out under similar conditions. 

 This, then, is the fate of the majority of the survivors of 

 the summer and autumn Nelson Buoy plaice fishery — they 

 migrate to the westward to risk the winter fishery there. 

 But in most of the experiments a few plaice have been 

 recaught about the end and the beginning of the year on 

 the banks near the north-east of the Isle of Man. These 

 are generally the larger plaice, and this migration is a 

 spawning one. 



Both the migration from Nelson Buoy towards Red 

 Wharf Bay, and that towards Bahama Bank are, like the 

 offshore migration from the nurseries to the Nelson Buoy 

 grounds, compensatory movements the effect of which is 

 to cause the fish to inhabit water of as nearly as possible 

 the same physical conditions. The migration outwards 

 from the nurseries is one from warmer water, rising in 

 temperature, into colder water; and those from Nelson 

 Buoy towards Bahama Bank and towards Red Wharf Bay 

 are migrations from colder water, falling in temperature 

 into warmer water. It is by reference to such compen- 

 satory migrations, the effect of which is to preserve as 

 nearly as possible the optimal conditions, that we must 



