SEA-FISHERIES LABORATORY. IAI 
THE MIGRATIONS OF PLAICE IN THE IRISH SHA. 
By James JOHNSTONE, D.Sc. 
The last plaice-marking experiments were made at the 
end of 1913, so that all the recaptures likely to be made must 
now have been reported. A summary has been prepared, 
and as this has some important bearings on the question of 
legal size-limits an abstract of the results is now presented. 
All the experiments made in the summer and autumn 
of the years 1905-1913 in the “ Nelson Buoy Area ”’ have been 
combined. Most of these experiments were made during 
the months June and July, one was made in September and 
one in October. _ About 1,100 plaice were marked and liberated, 
and the positions of recapture of about 280 of these fish have 
been traced. This is the material dealt with in the meantime. 
A series of charts have been prepared showing the positions 
of recapture, and the sizes of all the fish caught during each 
month from June to December, for the periods January to 
April, and May to September of the year following that of the 
experiment. These charts show as clearly as possible the 
general movement of the plaice shoals inhabiting the area 
of sea within the 20-fathom line off the coast of Lancashire. 
A further synoptical chart has been prepared showing 
the migrations. Contour lines have been drawn round the 
positions of recapture of all the fishes caught in June-July, 
in August, in September-October, in November-December, 
in January-April, and in May-September (the two latter periods 
applying to the year after that of the liberation of the fish). 
These contour lines represent successive “ fronts’? occupied 
by the moving shoal of fish during the periods mentioned. 
The evidence is very clear and convincing. It is not 
given here in the meantime, but I have prepared an abstract 
of the main conclusions. 
