112 SEA FISHERIES 



entered the trawl only 5 escaped, while 77 per cent, 

 of the haddock were captured ; but of whiting only 4 per 

 cent, were retained, 96 per cent, escaping the large 

 meshes. Other tests were made with pockets of different 

 mesh (8 inches, or 2 inches square, and zoj inches, or 

 2f inches square). The one net allowed 93 per cent, 

 of the fish caught to escape ; the other, 97 per cent. 

 These experiments refer only to the pocket of the trawl ; 

 the rest of the net being of a mesh 3 inches square allows 

 all the smaller fish to pass without difficulty. 



This inquiry, which was scientifically conducted, 

 teaches us more than one lesson. The otter-trawl is 

 evidently the direct cause of the diminution of the 

 numbers of flounders and of flat-fish in general. How- 

 ever, it is less deadly to the haddock, and scarcely affects 

 the round fish, and its effect in respect of herring is 

 insignificant. It is therefore certain that it does con- 

 tribute to the emptying of the North Sea, but in a very 

 limited degree. If by chance its ravages were greater than 

 this inquiry proves them to be, we should be forced to 

 attribute them to the indirect action of the otter-trawl 

 upon the fish ; that is, to the disturbance of the bottoms 

 which constitute the nurseries or spawning-grounds. It 

 must be remembered that such disturbances as these, 

 whether natural or artificial, are destructive agencies. It 

 is very probable that this is not simply a vain hypothesis, 

 although there is no actual proof of its truth. 



IV 



So far we have considered only the large trawl or otter- 

 trawl, which is employed in the Atlantic and on the 

 northern fishing-grounds. I must now say something of 

 the Mediterranean trawl, known as the ox-trawl or grand 

 gangui. The ox-trawl is drawn by heavy boats known as 



