Reducing the impact of mobile bottom-contacting fishing gears on seafloor habitats

A recent workshop invited stakeholders to provide feedback on the trade-off analysis between fisheries and the seafloor.
Published: 24 March 2021

​“The interconnectivity of all marine life through the food web means that every management action will have an effect to some degree on every part of the system. So measures designed to mitigate impacts on seabed integrity can be expected to have indirect effects elsewhere in the food web, even on top-predators." - Report of the Workshop to evaluate tradeoffs between the impact on seafloor habitats and provisions of catch/value WKTRADE, 2017

There are many different types of seafloor throughout the oceans which provide habitats for many marine species that live above, on, or in the seafloor.

Human activities can result in increased pressure on the seafloor: mining, extraction and dredging, coastal and offshore infrastructure, introduction of non-indigenous species, pollution, fishing and aquaculture practices.

Over the past five years, ICES has been carrying out a stepwise process to deliver guidance on seafloor integrity for Descriptor 6 of the European Commission's (EU) Marine Strategy Framework Directive (MSFD).

“Because bottom-contact fishing provides a major source of physical disturbance to the seabed around Europe, it affects many seabed habitats and is therefore a major pressure that needs to be addressed in order for Member States to achieve good environmental status under the Marine Strategy Framework Directive" says David Connor, Policy Officer, EU Directorate-General for the Environment.

In 2017, ICES held a series of workshops (WKBENTHWKSTAKE, and WKTRADE) to address an advice request from the European Commission to evaluate indicators for assessing pressure and impact on the seafloor from one human pressure – mobile bottom-contacting fishing - and demonstrate trade-offs in catch/value of landings relative to impacts and recovery potential of the seafloor. Methods for assessing seafloor impact from mobile bottom-contacting fishing gears were developed and from an ecosystem-based fisheries management perspective, these methods can also be used to inform managers about the interlinkages, and therefore trade-offs, between seafloor impacts and the socio-economic value from the fisheries. 

The resulting advice indicated that a large fraction of landings and revenue from bottom fisheries are obtained from a relatively small part of the area fished in the North Sea. This finding underscores a potential management option that reduces fishing impacts on the seabed with a relatively small cost to the fisheries.

In 2019, WKTRADE 2 advised on best practices to better reflect bio-economic cost and benefit tradeoffs and outlined progression towards potential management options which fully account for the socio-economic value of fisheries as well as the consequences of effort mitigation measures. 

Stakeholder involvement

Now, in 2021, the EU has requested ICES to advise on a set of management options to reduce the impact of mobile bottom contacting fishing gears on seafloor habitats, and for each option provide a trade-off analysis between fisheries and seafloor quality.

To ensure the analysis of all relevant management options, ICES invited stakeholders to participate in the first WKTRADE3 workshop, held online in March, to review management options on whether the trade-off analysis is informative, if useful outputs were produced, and what is needed to make informed decisions.  

Connor noted that the EU finds it essential to understand the views of stakeholders - particularly from the fishing industry and conservation communities – on how ICES will undertake the 'trade-offs' analyses and how it will present the results. “The stakeholders' views are important to validate the approaches being taken, and to allow for their adjustment where needed and possible."

Stakeholder engagement

All participants agree that stakeholder engagement should start as early as possible in any strategy.

Kenny Coull, Fisheries Policy Officer, Scottish White Fish Producers Association Limited (SWFPA) and Elena Balestri, Science Policy Officer, Scottish Fishermen's Federation (SFF) commented that, “We believe that before we are considering options for implementing or even considering a range of measures to reduce fishing footprint and impact, we need to recognise the significant reduction, over a relatively short time (20 years) in fleet size and capacity, therefore footprint and impact. Consequently, we then need to assess or evaluate the potential recovery to habitat and ecosystem that may already be delivered or underway. Once we know what that is, we are then in a better position to decide what is needed next rather than arbitrarily chose another level of reduction." 

Nicolas Fournier, Oceana, agrees on the importance of being involved in the process at an early point to be able to understand it, and to provide relevant information to support the advice process. “The process is scientifically sound with a selection of management options from recent publications about how to manage the negative impacts of bottom-trawling on the seafloor. But it is important to consult stakeholders to offer the opportunity to share views and data that may not be available to scientists. It is also important to increase the stakeholder's understanding of the scientific advice process, reinforcing buy-in and credibility."

“Informed involvement of all the sectors and interests involved in such a potentially contentious issue is of great value", notes Stephen Thompson, Eastern Inshore Fisheries and Conservation Authority, UK. “We believe Inshore Fisheries and Conservation Authorities (IFCAs) have a real role to play, due to our knowledge and experience of developing balance between sustainable fishing and conservation in the often complex and highly variable inshore areas, where a high degree of local knowledge is required. Whilst there will probably always be disagreements between sectors with different specific interests and drivers, having a structured informed platform from which to start discussions is the most productive way forwards."


On the options presented, Fournier noted, “As often in fisheries management we are dealing with patchy data availability, and this unfortunately resulted in several management options not being considered (e.g. patchy habitats distribution, poor coverage of small-scale vessels, data disparities between EU regions). This workshop nonetheless offered an opportunity to discuss these choices and assumptions, and from our perspective as an NGO, to defend alternative options which we think have a higher potential to deliver both conservation benefits and climate resilience overall. One of this is to reconsider nearshore restrictions for bottom-trawling, which already exist in parts of the EU like the Mediterranean Sea, and can be readily implemented for example on the basis of available information on the distribution of sensitive and carbon-rich habitats like seagrass and coralligenous beds."

Thompson considers that is important to understand that selection of management options is not an either/or choice. “In many instances, a combination of approaches (e.g. “closed areas" where the fishing gear is not compatible with the features to be protected, combined with gear modification to minimise impacts to acceptable levels in areas that can sustain some level of fishing, coupled with an understanding and possible limitation of fishing effort) is more appropriate to achieve the balance between nature conservation and allowing the continuation of sustainable fishing." He admits that this makes the process of assessing potential impacts much more complex when there are more variables and options, “but achieving this balance is so important that we have to find a way to do the difficult things, rather than just say it's too hard and default to an approach which will not deliver the best balance".

The SWFPA and SFF felt that there was insufficient time allocated to the evaluation of options. “The short duration of the workshop did not help us to evaluate the potential impact on the sectors we represent or the opportunity to focus on options and provide well thought-out views and feedback."


Participants were left with some concerns after the workshop.

The SWFPA and SFF ​stated that given the different approaches and feedback from the groups, there clearly were different messages. “We did not feel the workshop was of a duration that allowed for open and frank discussion and we finished having no idea what the key outputs (and messages) taken from this event were.  We were particularly concerned that this process still seems to be following a dictate from the EU and simply ticks the 'stakeholder engagement' box."

Fournier stated that he was “curious how ICES will use and integrate the stakeholders' views and positions into the advice building, particularly on issues where there are clear disagreements".

Thompson was concerned with the information available on the location and level of fishing effort by the inshore fleet. These small vessels are not obliged (in the UK) to have any form of VMS system, and the lack of such data can easily lead to the impression that the inshore areas are not important to certain sectors, such as beam trawls. “Nothing could be further from the truth – within our district, the close inshore areas (<6 nm.) are crucial to the low impact brown shrimp beam trawl fishery, but this activity did not show up on many of the maps shown at the WKTRADE 3 event. This is no fault of those working on the maps (which were based on VMS data), but must be recognised and addressed to give the full picture of activity. This is especially the case for an organization such as ICES, where due to the high respect rightly awarded to the information and advice coming out of the organization, there may be a temptation for “the powers that be" to simply take the maps at face value, and not appreciate the limitations and caveats associated with the underlying data."

Connor, however, felt that the workshop successfully achieved its aims. “The stakeholders, in large part, validated the approaches being followed by ICES to provide 'trade-off' analyses that will inform the MSFD policy process. The fisheries, conservation, and management communities brought valuable perspectives to the discussions during the workshop, which help inform the follow-up technical analyses to be undertaken by ICES."

He added, “Some discussions focused on more long-term management issues, such as ways in which fishing practices could be changed in order to increase the levels of protection to seabed habitats. Here, the different views expressed (fisheries, conservation, management) were important to hear, as they can help shape future actions and for this, further discussion with stakeholders will be needed to achieve a balance between protection of the seabed and continued exploitation of fish stocks".

Next workshop

The second part of WKTRADE3, an online technical workshop chaired by Jan Geert Hiddink​ and Josefine Egekvist, will evaluate the suite of management options prioritized by stakeholders for different EU marine regions and analyse their consequences for the overall benefit to seabed habitats and loss of fisheries values. 

Register for WKTRADE 3 taking place online April 6–9.​

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Two European Plaice or flatfish in the Scheldt Estuary, the Netherlands. Image: Jos de Schiffart Shutterstock.

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Reducing the impact of mobile bottom-contacting fishing gears on seafloor habitats

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