APPENDIX H: GARSTANG _ 26 — 



» 



The Migration Experiments and the Trawling Experiments together have already thrown 

 a large amount of new light upon all these points; but they have shown that the deficiency 

 of the rate of growth on the inshore grounds is much gTeater than was ever anticipated. It 

 is impossible to avoid the provisional correlation of this difference with corresponding local 

 differences in the abundance of plaice, — the rate of growth being remarkably deficient where 

 the population reaches its maximum, and being remarkably high on some of the more distant 

 grounds where the population is relatively low. 



This being so, it is scarcely a self-evident proposition that the protection of small plaice 

 on the inshore grounds would lead to an increase in the quantity (weight) of plaice available 

 for capture on the offshore grounds. According to my interpretation of the present evidence, 

 a material increase in the numbers of small plaice on the inshore grounds would still further 

 retard their rate of growth; and it is a debateable question whether this result would be to 

 the general advantage of the fisheries, since it is now generally admitted that the problem of 

 the impoverishment of the trawling grounds is one which depends more on a decline in the 

 size and weight of the fishes caught than on diminishing numbers. 



The method of otolith-examination has, however, afforded a reliable means ef determining 

 the age of individual fishes. The analysis by this method of the sizes of plaice on different 

 grounds will in a short time yield a great amount of new information as to the rate of growth 

 in specially selected areas. It will then be possible to determine the precise law or relation, 

 which exists between density of population and rate of growth on grounds of uniform character. 



These questions have further to be considered in relation to the intensity of fishing. The 

 results already attained suggest that this intensity is much greater inshore than offshore, in 

 consequence of the operations of the sailing fleets, the influence of which requires simultaneous 

 consideration with that of the steam trawlers. 



I hope by these remarks to show, on the one hand, that the investigations in progress 

 have a direct bearing upon the special problem at the head of this section, and, on the other 

 hand, that the time has not yet arrived for definite conclusions to be drawn. In the meantime 

 the results of the transplantation experiments are exceedingly encouraging for those who believe 

 that the supply of fish in the sea can be increased by a rational exploitation based upon 

 scientific experiments. 



