143 



in appraising the relative influence of sail and steam, that 

 marked fish may have been overlooked especially aboard 

 steam trawlers. On the other hand, it has to be 

 remembered that steamers are excluded from the 

 territorial waters in which the majority of the marked fish 

 were recaptured. On the whole, the figures in the table 

 agree fairly with practical experience of fishing methods 

 in the district. 



Rate of Growth of Plaice in the Irish Sea. 



This is very variable, as might be expected. The 



growth of a fish depends on the amount of food present on 



the ground which it inhabits, and it is well known that 



different grounds vary greatly in this respect. The 



present experiments were not favourable for observations 



on the rate of growth. In order to study this to the 



greatest advantage, a large number of fish would have to 



be marked and liberated before the period of the year 



when growth begins. We did, indeed, set free 566 before 



the end of March, but of these the great majority 



captured were taken before the end of July, and only a 



comparatively small number after that time. In May, 



June and July we set free 227 plaice, but few of these 



have been recaptured. Conclusions as to the general rate 



of growth based on these are not reliable. Up to the end 



of July, however, our figures afford reliable indications 



as to the growth rate. These figures are : — 



Average increase in length up to the middle of January 004 inch. 



Do. do. do. February ...0-04 



Do. do. do. March 007 



Do. do. do. . April 02 



Do. do. do. May 0-42 



Do. do. do. June 0-86 



Do. do. do. July 1'5 



Do. do. do. August 1-95 



Do, do. do, September... 2 -62 



