ON THE MIGRATIONS AND THE GROWTH OF PLAICE. 151 



Growth. — Attempts have frequently been made to state 

 the rate of growth for plaice, and the want of conformity in 

 the conclusions is no doubt due to the fact that there is a 

 considerable degree of variation brought about for the most 

 part by the long spawning period. The produce each year 

 thus varies greatly in size, and during growth they are to 

 some extent unequally affected by the successive seasons of 

 acceleration and retardation. The various regions in which 

 plaice occur are not equal either with regard to temperature 

 and food. The variations in the seasons also leave more or 

 less an impress on growth. 



The most important recent work on the subject has been 

 done by Fulton and Apstein, and notwithstanding that the 

 research was made in the one case on Scotch plaice, and in 

 the other on the plaice of the Baltic, the conclusions are very 

 much in accord. 



During the last six years I have carefully measured the fish 

 caught in the first haul at our trawling experiments, and in 

 my last report I brought together the results so far as they 

 related to the growth of the plaice. The experiment in 

 migration now under consideration serves to confirm the 

 determinations arrived at by an analysis of the plaice caught 

 by the trawl. I do not propose to give now, however, the 

 details in figures, nor the graphic consideration of these, which 

 have led to the conclusions given in the following table : — 



Plaice. 



Age. 



Average 

 Length. 



Gain. 



Average 

 Weight. 



Gain. 



Proportional 



Rate of Growth 



in Weight. 



Years. 



Inches. 



Inches. 



Ounces. 



Ounces. 





I 



3-9 





0-4 





... 



2 



7-9 



4-0 



3 



2*6 



650 



3 



IO-8 



2-9 



8 



5 



167 



4 



13 



2-2 



14-5 



6-5 



81 



5 



15 



2 



22"5 



8 



55 



6 



i6-8 



1-8 



31-5 



9 



40 



7 



18-4 



1-6 



40 



8-5 



27 



8 



19-4 



I 



47 



7 



18 



9 



20"2 



0-8 



53 



6 



13 



10 



20-8 



0-6 



57 



4 



^ 



