The eliminator trawl is a standard demersal trawl with very large diamond meshes in the wings and forward part of the trawl. It is designed this way to allow certain species to escape before they pass down to the cod-end.
The large mesh in the front of the trawl is very effective in letting the cod escape as soon as they have entered the trawl. With some adaption (reducing the very large mesh down to 300mm - 800mm) the trawl, while still letting a lot of cod escape still retains enough of other species to make it commercially viable.
The design was developed to allow the release Atlantic cod from a standard flat fish net with one of the objectives to allow fishermen back into areas where cod are more prevalent. This design was introduced in to UK fisheries after extensive trials in the North Sea.
The basic concept is to replace the netting in the front end of the trawl with netting made of much larger meshes, in this case increasing from around 160 - 200mm up to 2400mm mesh. These larger meshes extended back in the trawl to about 3 metres behind the fishing circle. Further back in the trawl the mesh size gradually reduced in size down the industry standard 80mm mesh cod-end. These larger meshes allowed much of the cod entering the trawl to escape through the larger mesh soon after they entered the mouth of the trawl. This is a fairly simple alteration to make to any trawl to enable the release of cod.
After the success of this gear in English waters Scotland also experimented with large mesh in the mouth of their trawls. They found that smaller mesh sizes 300mm - 800mm, gave better results in their fishery in that the gear released the cod but retained enough of the other species for the vessel to remain viable. The gear developed in Scotland became known as the Orkney Trawl.
All dimensions, mesh counts and cutting rates are for generic advice and information. Before constructing and fitting this gear into a trawl you should consult with your local fishery officers or legislators such as MMO, Marine Scotland and Daera in the UK. This should ensure that your gear meets the requirements of the area that your vessel will be fishing in.