20 THE IMrOVKRISHMENT OF THE SKA. 



In spite of all that has been said as to the inadequacy of the 

 Garland's experiments for yielding a scientific verdict on the effects 

 of the prohibition of trawling, there appears to me to be only one 

 possible conclusion from the foregoing figures ; viz. that there was a 

 general diminution both of plaice and lemon soles in the closed waters 

 after the prohibition of trawling, and a still more marked increase in 

 the abundance of dabs and long rough dabs. 



It must be remembered that whatever irregularities occurred in the 

 Garland's work as to the duration of the hauls of the trawl and such 

 matters, these necessarily affect the figures for all species of flat-fish 

 alike. The contrast remains that, under precisely the same experi- 

 mental and climatic conditions, plaice and lemon soles are seen to have 

 decreased, and dabs and long rough dabs to have increased during the 

 decade. 



Dr. Fulton's conclusions are, therefore, in all respects correct, so far 

 as I am able to determine, and are independent of the errors which 

 were associated with his methods of demonstration. 



Under these circumstances I see no reason for disputing Dr. Fulton's 

 principal explanation of the changes which were induced in the relative 

 abundance of fiat fishes in the closed waters during the period of pro- 

 hibited trawling. It appears to me to be reasonably established that 

 pari passu with the increased destruction of plaice and lemon soles 

 in the open waters, there has been a progressive diminution of these 

 fishes even in inshore waters which have been continuously protected 

 from the effects of trawling operations. It also appears to be satis- 

 factorily demonstrated that under the conditions just mentioned a con- 

 spicuous increase in the abundance of dabs and long rough dabs has 

 taken place in the inshore waters. 



Nevertheless, it is certainly open to reasonable doubt whether this 

 increase in dabs has been exclusively, or even mainly, due to the pro- 

 tection of the spawning grounds of these fishes; for the observed 

 increase of long rough dabs is as great as that of common dabs, yet, 

 from their preference for the deeper waters, the long rough dabs cannot 

 have received the same measure of protection as the common dabs 

 from the prohibition of inshore trawling. The possibility should be 

 borne in mind that the increase of dabs may have taken place quite 

 independently of the prohibition of trawling, in consequence of the 

 decrease of plaice and lemon soles with which they may be supposed 

 to be natural competitors — a suggestion previously made by my col- 

 league i\Ir. Holt, in connection with similar problems on the Devon- 

 shire coast {Jour. M. B. A., vol. v., 1898, p. 320). It is obvious that any 

 diminution of the species which normally maintain a rivalry with dabs 

 for the available food supply must confer an advantage upon the dabs, 



