Multi Rig - Quad rig

Summary

A method of towing four otter trawls side by side. The idea of multiple nets is to target a wide area of seabed with no increase in gear drag. This method is used to target bottom living species and nephrops.

Environmental impact

Any of the selective measures for a single trawl can be included in a quad rig trawl to improve its selectivity and reduce discards. Although this fishing method may appear dramatic it can be quite environmentally friendly. Several scientific trials of quad rig have evidenced that it catches much less round fish bycatch than a single or twin rig on the same fishing grounds. Used properly it should use less fuel for the same financial returns. Despite having many more nets the overall swept area and interaction with the seabed is usually less than or similar to that of a comparable twin rig vessel. the net used in this rig are very small with a very low headline height that restricts the number of round fish entering the trawl making them a good choice to target bottom living species without much by catch of round fish

Other information

In recent years in the North Sea some of the vessels from UK and Denmark have been experimenting with the use of more than two trawls. One method that has seen favour is the move from three warp twin rig to quad rigging. One of the main reasons is that there is no need for vessel alterations and the same three warps, trawl doors and clump weight can be used for both resulting in a the only major financial outlay being on 4 new smaller trawls. As they make the move from two to four nets the actual size of the gear is further reduced by about 30%. Quad rig allows the vessels to cover an even wider area of seabed but with a lower trawl headline height, this increases the nephrops catch but reduces the by catch of round fish such as haddock and whiting. The push for quad rig in Europe has mainly been by Danish and Rep of Ireland vessels.

Some of the Danish vessels have gone further than four trawls, trialling towing six nets using four warps, eight nets with five warps and even up to twelve nets. To tow this number of trawls needs great financial outlay in major vessel modifications and new gear to rig the vessel out. Apart from the few Danish vessels trialling these forms of multi rig there has been no sign of general acceptance within the industry in UK and EU of these multi rig methods by industry. It would appear that at this time the use four nets as a quad rig provides enough increase in efficiency and financial benefits without excessive complication and financial outlay

Gear classification

Main target species (UK)

  • Megrims
  • Monkfish
  • Nephrops

Possible bycatch

  • Any demersal species that frequents the nephrops grounds
  • Flats
  • Immature round fish
  • Juveniles of the target species