(For international audience)


As a freelance researcher and journalist Willem Ment den Heijer believes in pulse fishing. In these two (long read) articles (printed in Fishing News), Willem explains why pulse is a promising alternative for the traditional beam trawl.

Part 1

Since a big part of the Dutch beam trawl fleet switched over to the pulse technic the fuel consumption decreased considerably, the emission of carbon dioxide dropped, the by-catch of benthic organism reduced, the damage to the bottom has been decreased and the quality of the fish increased. 

The pulse trawl is a promising alternative for the traditional beam trawl which uses heavy tickler chains to chase the flatfish out of the sea bed and which has substantial collateral damage to the ecosystem. The skippers of pulse vessels are focussed on catching plaice and turbot and brill. The pulse fleet is more focussed on sole, although catches of other flatfish are still relevant. That does not mean that they are catching more sole than they used to do. In Holland we have individual quota for sole. The trawlers are only catching the amount of soles which is allowed according to their quota. 

There is no increase regarding the annual sole catch. That is not possible. But what the skippers of pulse beam trawlers notice is that they can sometimes catch more sole during one trip. If that means that his individual quota will be finished soon than the skipper will do his utmost to avoid areas where they catch sole easily. So the skippers are always keen on the balance of the species which are quoted. Although the pulse trawl is a promising alternative to reduce mechanical disturbance of the sea bed, carbon dioxide emissions and fuel costs, it is not clear whether electricity may have negative effects on marine organisms and the benthic ecosystem. 

As a freelance researcher I have been making a lot of trips during the last three years on pulse trawlers in order to take samples of the catch. Sampling was based on checking out the difference in juvenile fish of the two pulse trawl nets. One net had a square mesh panel of 3,2 metre long and approximately 1,2 metre wide and the other pulse trawl net just had 8 cm meshes Apart from the fact that the trials with an escape panel was working (but needed more improvements) all the small fish I was collecting was alive. Juvenile flatfish, whiting, gurnard, mullets, but also weever fish, daddy sculpin, dragonet, scuted teleost and solenette were al alive as well as sea sponges, sea snails, whelks and king scallops. 

No signs of being damaged or dizzy due to the electric pulses. For me it was an eye opener cause a lot of fishermen who are not familiar with the pulse trawl think that all marine animals will be dead in the cod-end. Two years ago a French fisherman (gill netter) joined a Dutch pulse trawler from Arnemuiden cause he was curious. He did not believe his eyes after the first haul was coming on deck. He thought that fish is already dead in the cod-end. I think it is worthwhile to do more investigation but for me it is clear that there will be no significant (lethal) effects of electrical pulses on small marine fish and organism.

Part 2

Rumours about declining stocks due to the use of pulse fishing do not have any evidence at all. Besides almost all commercial stocks in the North Sea are in a very good condition.  Dutch fishermen noticed that different types of skate are getting more common in the Dutch continental shelf. Even small scaled gill netters, operating close to the Dutch coast, are recording skate more often. Especially starry ray (Amblyraja radiata) which is the most common skate. It is good to criticize an innovative fishing technic because that will lead to more research. 

There is a multi-annual research program that has started in 2016 to study the size of selectivity and the effects on environmental aspects, fish species and other marine organisms. An international steering group guides the research and the annual international stakeholder dialogue meeting. The ICES Working Group on Electrical Trawling (WGELECTRA) is involved and the advice of  Advisory Committee (ACOM) has been accommodated in the research project. The ACOM is responsible for providing scientific advice to competent authorities in support of the sustainable management of marine resources and ecosystems throughout the North Atlantic Ocean. 

According to the Dutch ministry of Economic Affairs pulse trawling shows a reduction in discards benthic fauna and undersized fish of more than 50 %. During the first part of the research, done by Wageningen University and Research, the scientists were focussed on the effects of pulses on different fish species. The first results are positive. Numbers of X-ray photographs from dab, whiting, smelt, grey gurnard and dover sole (caught by pulse trawlers) show no damaged at all. 

Still it is clear to do more investigation in order to avoid rumours. Meanwhile pulse trawling is still a promising alternative to beam trawling.