362 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



much greater. Probably about 9 inches will represent the 

 average size of the fish caught ' in Morecambe Bay and 

 generally within the 3 miles limit. These fishes are now 

 marketable, and in suitable places all along the coast great 

 quantities at this size are caught in the stake nets. Larger 

 individuals are of course often got, but on these in-shore 

 fishing grounds mature Plaice are never or only very 

 exceptionally captured. It is these immature fishes which 

 in their gradual migration outwards form the mature 

 Plaice population of the more open sea. At or near the 

 spawning season they congregate on the spawning 

 grounds. 



Briefly summarized then the migratory movements of 

 the Plaice are (1) the passive drift in-shore of the develop- 

 ing eggs and metamorphosing larvae terminating as the 

 larva acquires the adult form and settles to the bottom, 

 and (2) the slow outward movement of the young fish, 

 deeper water being continually sought as it increases in 

 size. This movement ends as the fish becomes mature. 

 Thereafter its movements are probably very limited. 

 During the spawning season it probably does not travel at 

 all. With the extrusion of spawn another generation 

 begins the migratory cycle.* 



* We have described only the larger migrations which are part of the 

 life movements of the Plaice. Smaller and local migratory movements 

 are of course continually going on. Mr. R. L. Ascroft informs us of a 

 curious instance which illustrates the connection between these smaller 

 movements and physical events. A severe storm about 1885 was followed 

 by a very marked increase in the numbers of Plaice in one of the channels 

 of the Ribble estuary— the Bog Hole. For about four days great 

 quantities were caught, one of the sailing trawlers getting as much as 

 180 score of fish (value £30) in a day. The cause of this remarkable 

 abundance was that the storm and rough water washed off the " Sand 

 pipes" (Pectinaria belgica), which existed in great abundance on the 

 neighbouring banks, into the channel, and the Plaice followed the food. 



