392 



A HISTORY OF FISHES 



As the net is towed slowly along the sea-floor, the resistance of 

 the water causes the two doors to pull away from one another, 

 each door with its attached warp acting after the manner of a 

 boy's kite. This trawl has a great advantage over that of the 

 beam variety in that the size of the opening is not limited by 

 the size of the frame, and the mouth of a modern otter trawl 



may be anything up 

 to one hundred feet 

 in width. At the same 

 time the beam keeps 

 the mouth of the net 

 open even if the 

 vessel loses way, 

 whereas if a [boat 

 towing an otter trawl 

 comes to a stop, the 

 boards tend to fall 

 down flat and may 

 not always come into 

 position again when 

 the vessel begins to 

 move once more. An 

 important modifica- 

 tion of the otter trawl 

 largely adopted in 

 recent years is known 

 as the "Vigneron- 

 Dahl Trawl." In 

 this net the wings are 

 longer than in the 

 ordinary trawl, giving 

 a greater mouth open- 

 ing or "fishing 

 Fig. 139. spread," and the 



Diagram to illustrate the principle of working a ground warns being 

 Seine Net from the shore (seen in plan). -^ ^j^^^ ^^^^^^^ ^.^j^ 



the sea-floor tend to scare the fish inwards towards the track of 

 the net. 



Several types of seine net are in use in various countries, but 

 cannot be described in detail here. Briefly, seining consists in 

 surrounding a shoal of fish with a long net, suitably buoyed, 

 and gradually drawing this closer until the imprisoned fish 

 can be readily removed. The net is usually paid out by a boat 



