Pulse Trawling

Pulse trawling (also known as electro trawling) is a technologically advanced – and highly controversial – method of commercial fishing which has only been used on an experimental basis up until now, but appears to making a major breakthrough into mainstream commercial fishing across Europe’s fisheries.

Pulse Trawl

Pulse trawling uses electrodes mounted into nets to shock fish out of the seabed and into the net.

Development of Pulse Trawling

Pulse trawling is an adaptation of beam trawling, a method of commercial fishing which has been used for over one hundred years. Beam trawling is used to catch demersal species (those that live and feed on or near the seabed). The mouth of the net is held open by a solid metal bar and up to twenty ‘tickler chains’ thrash the seabed in front of the net to stir up fish (especially flatfish and prawns which bury themselves under the sand and silt of the seabed) which then allows them to be scooped into the net. Beam trawling is considered one of the most environmentally destructive forms of trawling by environmental groups such as Greenpeace due to the very high levels of bycatch and the damage to the seabed that this type of fishing causes.

The pulse trawling system was invented by in the Netherlands by Piet Jan Verburg in 1992. This method of fishing replaces the tickler chains of traditional beam trawling with a series of electrical drag wires mounted into the net. These wires create an electrical field around the net which shocks and stuns fish out of the seabed and moves them into the net (1). The Dutch have remained the biggest proponents of pulse trawling and have advanced the use of this technology claiming that pulse gear has less contact with the seabed meaning that there is more of the target species caught, lower levels of bycatch, less damage to the seabed and fish that are caught have less damage done to them and therefore reach a higher price at market. Furthermore, and the point that is of most interest to commercial fishermen if that pulse trawls are up to ten times lighter than traditional beam trawl gear (9), meaning that fishing with pulse gear uses up to 40% less fuel than traditional beam trawling (1), (2) . Although it costs on around £300,000 to convert a beam trawler to a pulse trawler and retrain the crew to use the new equipment, the savings that can be made mean that this investment can soon repay itself.

Pulse Trawling: Officially Banned by the EU, But Increasing in Use

It is important to note that officially pulse trawling is banned in European waters by the EU. Article 31 of Council Regulation (EC) No 850/98 covers unconventional fishing methods and states:

“The catching of marine organisms using methods incorporating the use of explosives, poisonous or stupefying substances or electric current shall be prohibited.”

Emphasis added.

Technically, this makes pulse trawling, or any kind of fishing using an electric current illegal anywhere in the European Union. However, a legal exception is made to allow pulse trawling to be carried out for research purposes. This gives fishermen a way around the ban by allowing them to fish using pulse trawling gear as long as they claim they are only doing so as part of a research programme.

Impact and Expansion

Burrowed flatfish

Flatfish which bury themselves under the sand, such as this brill, are the target of pulse trawlers.

However, the evidence of pulse trawls that have been used in the real world does suggest that they are as safe as has been claimed. Pulse trawling was used extensively in the East China Sea in the 1990s to catch shrimp. By the year 2000 there were around 10,000 beam trawlers working the area, 3000 of which were equipped with pulse trawling gear (3). Catches of all kinds of shrimp, especially the burrowing species of shrimp, began to go up. However, lack of regulation meant that different levels of power were being used in the pulse gear, and it soon became apparent that damage was being caused to both juvenile shrimp populations and other benthic species (those that live in the seabed itself such as crabs, shellfish and starfish) (3), (4) . Pulse trawling was therefore banned in the seas around Zhejiang Province which had previously been the most popular area for pulse trawling, and the rest of the East China Sea soon followed (3) .

Despite the official ban on pulse trawling its use has been expanding across European waters. In 2007 a number of pulse trawlers have been allowed to operate, using the experimental basis of this type of trawling to circumvent the EU ban on fishing with electric currents. The Dutch fishing industry has lobbied to allow greater freedom to use pulse and electrical trawling gear and in 2010 they were partially successful in getting the restrictions on pulse trawling eased – a maximum of 5% of the Dutch commercial fishing fleet was allowed to use electrical fishing gear. This may have seemed like a small rise but it meant a quadrupling of the number of pulse equipped vessels. In 2012, the amount of Dutch trawlers allowed to operate pulse trawls was increased to 10% of the fleet by the EU, showing that the European Union had little intention on upholding its own ban on this type of fishing.

Due to Europe’s Common Fisheries Policy (CFP) Dutch pulse trawlers were permitted to operate within twelve miles of Britain’s coastline and fishermen working out of ports in Essex and Kent certainly do not agree with the Dutch view that pulse trawling is a clean, safe and environmentally responsible way to catch fish. Reports began to emerge that masses of dead Dover sole were being brought up in the British trawler’s nets and the number of live and healthy flatfish, particularly sole, had declined dramatically. In an article in the Sunday Times the fishermen directed the blame squarely at the Dutch:

[It’s like] “fishing in a graveyard…What they don’t catch they annihilate…Virtually everything is dead.” – Tom Brown, Secretary of Thanet Fisherman Association.

“This is absolutely devastating for us because we never caught so many fish that [were] already dead…It’s a waste of time going to that area now. It stinks of dead fish.” – Jeff Loveland, owner of two fishing boats operating out of Ramsgate, Kent.

“I have fished there for 30 years and never seen anything like it. I think the pulse is killing the food in the seabed. Three years ago I caught 40 tons of sole in those grounds in one year. It was the best year we’ve ever had. There is nothing there now that I can catch.” – Roger Free, commercial fisherman from West Mersea, Essex.

Despite the concerns of British commercial fishermen pulse trawling has been quietly allowed to expand into British waters. Twelve fishing vessels which are registered under a British flag now operate pulse trawling gear, meaning they can operate within the twelve mile zone from the British coastline which was previously protected from this type of fishing. However, George Monbiot, writing in the Guardian in February 2015, stated that it is highly likely that at least some of these vessels are financed and equipped by the Dutch fishing industry, even though they are registered as United Kingdom fishing boats. This expansion in pulse trawling is often referred to as a ‘trial’ or ‘research exercise’ to get around the EU ban, although this does not change the fact that these vessels are actively fishing using electrified pulse trawls within British waters.

Pulse Trawl

Simplified diagram of a pulse trawl in action.

A study into pulse trawling by the ICES (International Council for the Exploration of the Sea) backed up the claims of the British fishermen. The study found that cod which were close to the pulse trawl gear (but not caught in the net) suffered from cracked vertebrae and internal hemorrhaging, and pulse trawling has the potential to increase mortality rates in cod, although more research was needed (5). The study went on to say that less fuel was used by vessels using electric gear, and there was a lower bycatch of benethic species. However, it was also stated that “there are indications that the gear could inflict increased mortality on target and non-target species that contact the gear but are not retained” (5), and the study warned that pulse trawling in the real world could have a significantly different impact on the marine environment than they predicted (5). Further research was advised and it was stressed that pulse trawling should only continue on a limited scale and in a highly regulated way (5) (although this has not stopped the Dutch and British expanding pulse trawling in 2014 and early 2015).

Further evidence of the destructive impact of pulse trawling was gathered in 2013 when an article published in the peer-reviewed academic journal Fish and Fisheries found that pulse trawling had a serious impact on fish eggs and embryos in a freshwater environment (6). An article in The Independent in March 2015 likened pulse trawling to fracking (i.e. something which is meant to be clean but in effect has major environmental impacts) and also said that entire areas could end up being “fished out” due to the effectiveness of pulse trawling (7).

The Future

Up until 2014 pulse trawling was still fairly rare. However, with the Dutch fishing industry pushing hard for greater acceptance of this technology, and the European Union appears reluctant to back its own ban on using this technology in European waters. There is also pressure from some sections of the commercial fishing sector across Europe who are attracted by the lower fuel costs and better quality catch. Already ‘British’ pulse trawlers are operating in the North Sea, and some commercial fishing companies believe it is only a matter of time before pulse trawling becomes more common than traditional beam trawling (8), and fishermen who have spend over quarter of a million pounds converting their vessels into pulse trawlers will not revert back to conventional fishing without a fight. In 2017 pulse trawling’s transformation into a mainstream commercial fishing method moved another step closer with Elisa Roller, ?the Head of Unit at Directorate General Maritime and Fisheries Affairs of the European Commission, told a meeting at the EU parliament that pulse trawling was “the most innovative, most researched and most fuel-efficient gear” to use in commercial fishing. She went on to say that she was sufficiently satisfied by the research that had been carried out to allow pulse trawling to become a mainstream method in EU waters.

It remains to be see what consequences this will have on Europe’s fish populations and the wider marine ecosystem.

References:

1. Pulse Trawling – Ecomare.nl.
2. Pulse Trawling – zeeinzicht.nl.
3. Yu, C., Chen, Z., Chen, L., and He, P. (2007) The Rise and Fall of Electrical Shrimp Beam Trawling in the East China Sea: Technology, Fishery, and Conservation Implications. – ICES Journal of Marine Science, Issue 64.
4. Zapped: Britain’s Fishing Graveyard – The Sunday Times, 24/6/12
5.
6. Monbiot, G. (2015) We should be outraged by Europe slaughtering sea life in the name of ‘science’, The Guardian.
7. McCarthy, M. (2016) Nature studies: Pulse fishing is the ‘Marine Equivalent of Fracking’, The Independent.
8. Pulse Trawl – Orion Fishing.

9. http://upflow.co/l/8Ub3/news/pulse-trawling-set-to-get-green-light

Share this page: