Beam Trawl - Pulse trawl

Alternative names

  • Sumwing pulse trawl
  • Electric fishing

Summary

The pulse trawl is a development of a standard beam trawl as a method of targeting bottom living species but in particular Dover sole. Using the standard beam and beam shoes the ticker chains and heavy ground gear has been replaced with a series of wire electrodes that pass an electrical pulse onto the seabed to stimulate the fish to rise up and fall back into the trawl. The beam if often replaced with a hydro dynamically shaped Sum wing beam arrangement to further reduce seabed impact.

A pulse beam trawl in use

Environmental impact

The pulse trawl has been developed over many years to replace the traditional beam trawl gear to reduce its seabed impact, reduce discards and reduce fuel consumption. The pulse trawl has done this but there is some controversy over its true impacts on the seabed and marine environment. More information on this can be found at http://www.pulse.eu.com/.

 

Other information

The pulse beam trawl was developed  from traditional beam trawl design with the targets being to reduce the seabed impact, reduce discards and cut fuel consumption. The main aim of this was to improve the environmental credentials of the Dutch beam trawl fleet.

Fishing with electricity has been trialled on many occasions in the past. However fishing with electricity is in effect banned within European waters. Therefore all the development and use of pulse beam trawling has had to be done under a dispensation from this regulation.

The Dutch developed a system where there was a series of electrodes trailing from the beam down to the seabed in front of the trawl.   By sending a series of low voltage pulses  through these electrodes into the seabed they can make the Dover sole and other fish rise off the seabed and drop back into the trawl. the power and frequency of these pulse has been perfected to suit their main target species of Dover sole.   he electric current was delivered from the vessel to the gear by a long cable stored on a self tensioning winch.

The environmental credentials of the gear was further improved by the development of the Sumwing style beam that was designed to skip just above the seabed with minimal seabed contact.

Recently some net makers have designed purpose built trawl to suit the rigging for the pulse trawl. As a result of the electrodes being able to support the leading edge of the trawl they are now making this leading edge much wider that makes the gear more efficient for bottom living species.

However there is a lot of criticism of the pulse trawl due to the possibility of adverse effects on other species.  There several investigative projects on going to better understand the true impacts of pulse trawling on the seabed and the marine environment.

Gear classification

Main target species (UK)

  • Dover Sole
  • Lemon Sole
  • Plaice

Possible bycatch

  • Any demersal species