Pulse trawling could be a more benign ecological option than conventional beam trawling if properly understood and adequately controlled, though this comes with a number of caveats and unresolved questions.
Although the pulse systems currently used don't appear to have major negative impacts, ICES considers the existing regulatory framework insufficient to prevent the introduction of systems that potentially could have such impacts.
One aspect relates to the power, shape, and frequency of the electrical waves sent out by the electrodes rigged onto the fishing gear. To avoid development of pulse systems that are potentially harmful for the ecosystem, the advice recommends the undertaking of experiments to identify the key pulse characteristics and thresholds below which there is no evidence of significant long-term negative impact on marine organisms and benthic communities.
There are also outstanding questions on the delayed mortality of species, as well as on how the electricity might affect them in other ways such as reproductively. There is now more knowledge on medium-term effects, although it is unclear whether injuries sustained as a result of the pulse trawling are limited to cod or extend to other gadoid species.
The advice also states not to generalize the research results to allow the expansion of pulse trawl to other areas or to use new technology without an appropriate impact assessment.
It was also found that with the current pulse characteristics the risk of detrimental impact on species and habitats covered by the Natura 2000 Directives is considered low.
Pulse trawl net; photo: Ecomare