Since it was first introduced in Europe in 2006, the use of electrical pulse fishing for flatfish and shrimp has raised questions from skeptics about the unknown effects on marine organisms, the potential detriment to biodiversity and the benthic ecosystem, and the way in which it alters fishing effort and catch efficiency.
Such concern over their use means that pulse trawls are currently banned under European Union legislation. However, 80 Dutch registered vessels fishing in the North Sea have been granted a derogation until 2019 for the purpose of research.
In traditional beam trawls, a tickler chain disturbs the seabed in front of the mouth of a net, facilitating capture of fish. In a pulse trawl, the tickler chain is replaced with electrodes attached to the net, which send out a low-voltage and low-frequency electrical pulse. This causes a tailflip in shrimps and a cramp response in flatfish, and makes it easy to scoop them up in the net. Experiments have also shown that the bycatch of benthic invertebrates is substantially reduced, which is particularly useful in the shrimp trawl.
However, concerns remain over the effects on bycatch of roundfish such as cod, in which vertebral fractures have been observed.
Dutch fisherman Cor Vonk, owns the pulse/beam trawler TX-1 Klasina-J, with his father and brother, and started pulse fishing in 2011, using a 10-volt pulse.
“We were one of the first vessels in the Netherlands to transfer from beam trawl to pulse, and the change cost several hundred thousand euros,” he said. “We soon discovered that there was a lot to learn and it took us well over a year before we really got to grips with what we were doing. From then on, once we were using it properly, the economics started to make sense.”
Vonk explained that each trip with the beam trawl uses around 38 tons of gas oil, but with the pulse trawl, their consumption is closer to 16 tons.
“We were amazed to reduce our fuel usage by more than half and were impressed when Wageningen Marine Research (formerly IMARES) also calculated a 60 percent carbon dioxide reduction,” he said.
The Klasina-J catches the same amount of sole with the pulse as with the beam trawl, and their catch of plaice, turbot, and brill is around half.
“This means that we have 50 percent fewer discards with the pulse, which is good for the ecosystem,” Vonk said. “Also, because our nets do not make contact with the seabed, there is minimal damage to the benthos. Another plus for us is that those nets last a lot longer, so our expenses are reduced considerably.”
In November 2016, the Netherlands sole and plaice pulse fishery, managed by the Cooperative Fisheries Organisation of the Netherlands (CVO), was turned down for Marine Stewardship Council (MSC) Certification.
Certifier Acoura Marine found that while the fishery met the requirements of MSC’s Principles 1 and 3, which deal with healthy target stocks and effective fishery management, it just fell short of meeting those for Principle 2, which addresses ecosystem impacts, and was therefore not recommended for certification.
Acoura Marine argued that while the physical impacts of pulse fishing on the seabed were lower than those of conventional beam trawl fishing, there was insufficient knowledge of its impacts on seabed ecosystems to state with certainty that pulse fishing does not have any significant impacts. Additional research and a longer time series of data was needed before the fishery could be reconsidered for certification.
Jurgen Batsleer, of the Dutch fishermens organization VisNed, explained that many of these issues were already being addressed, with Wageningen Marine Research conducting a four-year research program to study the effects of electric pulses on the ecosystem. The research group will present its results in 2019.
“We are looking at the short- and long-term functioning and chemistry of the seabed ecosystem, at the internal effects on fish, eggs and larvae, and on bycatch. At the same time, we are building up a detailed picture of the fishery distribution and landings, as well as interactions with endangered, threatened or protected species is being built up,” he said. “We are also about to start a project looking at the effects of the shrimp pulse, and it will be interesting to see how these compare with the flatfish pulse.”
An issue with control and enforcement highlighted by the MSC assessment has already been addressed by the fishery’s management authority, with enforced use of logbooks and the recording of voltages amplitudes used for each trawl put in place in January 2017. In addition, an independent certification for pulse has been agreed, which sets out the requirements with which all pulse vessels must comply.
Batsleer believes that acceptance of pulse fishing under the Common Fisheries Policy (CFP), moving from derogation to admission, would help the case for MSC certification.
“The European Commission has proposed to the council and the European Parliament in the draft regulation for technical measures, that this fishing method should be formally and definitively permitted. However, the matter is still being contested by several E.U. countries and NGOs,” he said.
Batsleer is hopeful that the results of the extensive research project will provide sufficient positive information for another attempt at MSC certification within a couple of years, and that this could open the way for greater use of pulse fishing in Europe.
