25 
size of the plaice further south results from the practically 
unrestricted exercise of this method of fishing. 
The size of the plaice captured also suggests some 
doubts as to the accuracy of the generally accepted theory 
of the life history and migrations of that fish. It is 
usually stated that the mature plaice inhabits and spawns 
in comparatively deep water (10 to 20 fathoms), that, the 
fertilised eggs and larve drift inwards towards shallow 
water, and that as the fish grows it migrates outwards 
towards the 20 fathom line. The observations made in 
Luce Bay, where plaice of 20 inches in length were found 
close in towards the shore in water of six fathoms and less 
in depth, show, however, that the above distribution is not 
universal, and that there is no necessary relationship 
between the depth of water and the size of the fish on the 
bottom.* Large plaice are found in Luce Bay because 
trawling is prohibited there and they are not interfered 
with. It is, however, reasonable to suppose that the 
absence of mature plaice on the inshore grounds of such 
an area as the Lancashire and Cheshire District is due to 
the great extent to which these grounds have been fished 
over. The amount of fshing on the inshore grounds is 
much greater than in deeper water, and the fish on the 
latter area are much less disturbed. ‘The eftect of this 
extensive fishing inshore has been to reduce greatly the 
average size of the plaice present, and it is to be noted 
that investigations into the hfe history of this fish have 
been made in comparatively recent times—since the ex- 
ploitation of the inshore grounds by the trawlers on the 
modern scale has taken place. This effect of trawling in 
reducing the average size of the fishes present on a 
ground is well known, and was first demonstrated by 
* Our observations, however, have been confined to the months of 
October and November. Possibly the large plaice may migrate from 
the Bay in winter and during the spawning season. 
