— XXIX — RAPPORT 1903-04 ANNEXE GC 
From these data charts are in preparation, and are nearly completed, showing 
(1) the Average Size of Plaice at each trawling station; 
(2) the Abundance (Catch per Hour) of Large and Small Plaice (i. e. ex- 
ceeding and less than 30 cm. total length) at each station for each 
quarter of the year. 
(8) the Percentage of Plaice below 20 cm. total length at each station 
for each quarter of the year. 
The practical treatment of problems affecting the trawl-fisheries depends 
very largely on a knowledge of the effects of trawling, under commercial con- 
ditions, on the vitality of the fishes caught. Special experiments on this point 
have been made by the English steamer, though many more are still to be desired. 
I have made an analysis of the results of these experiments for inclusion in the 
interim veport, and have drawn some preliminary conclusions both from the 
special experiments which have been made, and from a comparison of the percen- 
tages of marked fish recovered. In certain experiments the low percentage of re- 
coveries appears to be traceable to imperceptible injuries sustained by the fish 
during capture rather than to any defect in the methods employed. 
The treatment of the important problem of the Rate of Growth of Plaice 
is reserved for the definite triennial report of the Committee, since the results of 
recent researches of great importance, based on the examination of otoliths, are 
not yet available. Extensive investigations by this method are being carried out 
both in Germany and England. 
Several other questions are also of necessity deferred until the different 
countries have published their results independently, e.g. spawning grounds, fecun- 
dity, size of maturity, and distribution of eggs and larvae. 
Lowestoft, 15th August 1904 
WALTER GARSTANG 
Convener 
