166 SEA FISHERIES 



Domergue in the Bay of Biscay, on board the Vienne, 

 have shown that beyond a depth of 80 fathoms the sole, 

 turbot, and brill are no longer found. 1 Towards a depth 

 of 1 60 fathoms in the Atlantic a few flat-fish of the more 

 valued species are to be found, including the merry-sole 

 (P. megastoma), together with hake and certain Mediter- 

 ranean species. On the slope of the continental plateau 

 the capture of deep-sea forms of the Macruridce warns us 

 that between 160 and 270 fathoms the marine fauna has 

 undergone a radical transformation ; there are no more 

 edible fish. There are therefore no fishing-grounds at 

 a greater depth than 1,600 feet ; and those which can 

 be fished with profit are in less than 660 feet, or no 

 fathoms. In none of the depths explored have young 

 immature flat-fish been found. 



Whatever their species, fish are always on the move. 

 Two hauls of the trawl made in the same locality at 

 an interval of three or four hours will often give different 

 results. But the amplitude of their movements is very 

 small as compared with the vast extent of the seas. 

 These movements affect masses of fish ; sometimes 

 whole groups of species at once ; sometimes one species 

 after another ; but they never take any species beyond 

 the limits of its normal habitat. The menhaden or 

 American herring is unknown in Europe. The Baltic 

 herring forms a separate race, of smaller size than the 

 English herring. There are almost as many races as 

 localities. The Dutch adult herring is a large fish ; on 

 the banks of Iceland, in the Shetlands, and in Norway, 

 the herring is still longer and heavier : 400 Iceland 

 herring will fill a barrel, while 800 Channel herring 

 are required. The herring of the Zuyder Zee is not 



1 One single specimen of sole was taken from a depth of 120 

 fathoms near the bottom of the Arguin bank. 



