Nature Conservation Advice from NatureScot and JNCC: Demersal Fisheries Management Plans

5 Risks to UK Marine Strategy Descriptors

5.1 The UK Marine Strategy and FMPs

The UK Marine Strategy Regulations 2010 (SI 2010/1627) provide the policy framework for delivering marine environmental policy at the UK level and set out how the vision of clean, healthy, safe, productive and biologically diverse oceans and seas will be achieved. The Regulations require authorities to define the characteristics of Good Environmental Status (GES) and in turn develop an associated Programme of Measures required to deliver GES. GES establishes a ‘benchmark’ for our seas which seeks to ‘protect the marine environment, preventing its deterioration and restoring it where practical, while allowing sustainable use of marine resources’. For each Descriptor there are a number of practical targets and indicators that facilitate assessment of our delivery against each descriptor.

The UK Secretary of State sets the characteristics of GES every 6 years via a suite of ‘Descriptors’ that collectively indicate the health of our seas. More information about the UK Marine Strategy can be found via the Marine Online Assessment Tool (MOAT) portal, hosted by Cefas: Introduction to UK Marine Strategy - Marine online assessment tool (cefas.co.uk). The UK Marine Strategy GES Descriptors are assessed as part of a 6-yearly assessment cycle; an updated assessment of our seas will be presented in 2024.

The UK Marine Strategy Regulations require management action to be taken to achieve or maintain GES. The Strategy applies an ecosystem-based approach to the management of all relevant human activities. In doing so, it seeks to keep the collective pressure of human activities within levels compatible with the achievement of GES and does not compromise the capacity of marine ecosystems to respond to human-induced changes. The Fisheries Act (2020) enables regulators to deliver on this ambition through the Ecosystem Objective, which states that fish and aquaculture activities should be managed using an ecosystem-based approach, which is, in-part, defined in the Act by the achievement of GES. Equally, the recently published Joint Fisheries Statement (2022) lays out the ambition across UK administrations to take action to achieve or maintain Good Environmental Status (GES) in all UK waters (Joint Fisheries Statement, 2022).

The full list of UK MS descriptors can be seen in Annex 1. This advice focuses only on the most relevant descriptors in terms of risks posed by commercial and recreational fisheries: D1 biodiversity, D4 foodwebs, D6 seafloor integrity and D10 marine litter. Additional consideration of screened-out descriptors may be required in the future if evidence emerges of those descriptors being vulnerable to pressures generated by demersal fisheries. Furthermore, the status of many of the current indicators is currently ‘uncertain’ or ‘unassessed’ (see Annex 2). As the evidence base develops, or the suite of indicators associated with a specific descriptor evolves (e.g., after review in 2024), the advice pertinent to those descriptors will need to be updated.

UK Marine Strategy Descriptor D3 (commercial fish and shellfish) focuses on achieving maximum sustainable yield (MSY) for commercially exploited stocks. The indicators prioritise maintaining reproductive capacity and fishing mortality rates that support MSY. As the primary objective of this Fisheries Management Plan is establishing sustainable exploitation of the target stocks, following the precautionary and sustainability principles outlined in the UK Fisheries Act, significant progress should be made toward meeting Good Environmental Status for D3. While risks exist due to current exploitation levels and data limitations, the plan's emphasis on long-term stock viability provides a pathway for reducing these risks. We therefore do not present detailed advice for D3 here, as the plan’s development process directly addresses the descriptor through its foundational objectives. However, it is noted that achieving D3 targets alone may not fully support GES for associated descriptors, like D1 (biodiversity) and D4 (food webs), that require wider ecosystem considerations beyond single-stock MSY.

In the UK MS, these descriptors are assessed using indicators for each of their constituent ‘ecosystem components.’ This is carried through to this advice resulting in advice on risks to seven descriptor-ecosystem component combinations: D1, D4 cetaceans; D1, D4 seals; D1, D4 seabirds; D1, D4 fish; D4 foodwebs; D1, D6 seafloor integrity and D10 Marine Litter.

5.2 Assessing risk to UK MS Descriptors

This section provides an overview of the main risks posed to UK MS Descriptors by gear types likely to be covered by the Demersal FMPs.

The advice draws upon an existing risk analysis by French et al. (2022), conducted for Natural England as part of a REM prioritisation exercise, which evaluated the impact of various fishing gears on GES descriptors. This study has provided a good foundation for the risk assessment conducted here; although the work focused on fishing interactions relevant to English inshore waters, a broad approach was undertaken in screening-in metiers, and while we acknowledge that there may be gaps from a Scottish perspective, these are not anticipated to significantly alter the risk ratings.

This advice considers the ‘overall risk scores’ from French et al. (2022), using or adapting these based on additional relevant evidence (e.g., specific to the FMP) and/or expert opinion. The risk rating assigned isn't merely an assessment of gear-feature interaction but also gauges the overall risk in the FMP's context. For instance, a high-risk activity constituting a minor portion of the fishing activity under the FMP might have its risk rating downgraded.

The risk ratings aim to provide a pragmatic direction on the significant concerns regarding interactions between fishing gear types and UK MS descriptors for this FMP. A description of how these risk ratings were derived is given in section 2.1 above. It should be noted that the work undertaken by French et al. (2022) used a slightly different grouping of UK MS descriptors to those used in this advice - see Objective 1 in their paper for the full methodology and associated literature reviews.

Our assessment specifically highlights demersal trawls and seines, static nets and longlines as the gears of relevance to the Demersal FMP. These gears are actively employed across the UK in demersal fisheries for the species listed. Should the Marine Directorate or FMP delivery partners require more information on unmentioned gear types, NatureScot and the Joint Nature Conservation Committee (JNCC) can offer advice or suggest suitable proxies.

5.3 Risks to UK MS Descriptors

The risks to UK MS descriptors are detailed in Tables 1 - 3 below. Sections 5.3.1- 5.3.7 elaborate on the justifications for these risk ratings.

5.3.1 UK MS Descriptor D1, D4 biological diversity of cetaceans

The current targets and indicators for the Descriptor ‘D1, D4 Biological diversity of cetaceans’ are set out in Table A2 (Annex 2). A summary of the risks and actions for this descriptor are found in Table 1 for demersal trawls and seines and Table 2 for static nets, and Table 3 for longlines. Potential risks to this UK MS descriptor arising from the fisheries contained in the Demersal FMPs arise primarily from bycatch of descriptors and from reductions in available prey to descriptors.

5.3.1.1 Risks to cetaceans from bycatch

To be compatible with UK MS GES targets, fisheries must not result in a situation where the long-term viability of a cetacean population is threatened by incidental bycatch. In addition, there should be no significant decrease in abundance caused by human activities and the population range should not be significantly lower than the favourable reference value for the species.

Bycatch in static net fisheries is a significant source of mortality for many cetacean species. Both harbour porpoise and common dolphin are regularly recorded as bycatch in static net fisheries through the BMP, though much of this is suggested to occur outside Scottish waters. Bycatch is also the highest conservation threat for bottlenose dolphin. There are limited records of bottlenose dolphin bycatch through the BMP, but bycatch is likely to be localised for this species and not adequately represented within the ongoing monitoring programme.

5.3.1.2 Risks to cetaceans from reductions in prey

Links between harbour porpoise and reductions in gadoids have already been discussed in Section 3.1.2.1., with further discussion of the impacts of reduced availability of demersal fish species on cetaceans in Section 4.1.2.

To summarise, small demersal fish such as juvenile whiting and cod contribute to the diets of a number of cetacean species across the Scottish waters. The relative importance of these prey species is not clear and tend to contribute to a more generalised diet which alters relative to prey species availability and abundance. Patterns of prey availability can influence cetacean distribution and abundance. Foodwebs dynamics in the UK are difficult to predict, but it is likely that the removal of target species at the scale and diversity of demersal fisheries covered by the Demersal FMPs is likely to have direct and indirect impacts on prey available to marine predators.

5.3.1.3 Conclusions and recommended actions for D1, D4 cetaceans

There is a high risk to achieving GES for the biological biodiversity of cetaceans due to impacts from demersal fishing activities. This rating is primarily driven by risk of bycatch in static net fisheries. Continued monitoring and enhanced data collection and research to address knowledge gaps may allow us to reassess or improve the geographical specificity of this risk rating in future.

Whilst the reduction of prey species is considered to be a moderate risk, there is further work required to better understand the potential impacts of prey reduction on cetacean populations.

This assessment adopts a precautionary stance given the significant data gaps. As further evidence is collected and analysed, the risk assessment may be revisited.

5.3.2 UK MS Descriptor D1, D4 biological diversity of seals

The current targets and indicator for the Descriptor ‘D1, D4 Biological diversity of seals is maintained’ are shown in Table A3 (Annex 2). A summary of the risks and actions for this descriptor are found in Tables 1 - 3.

5.3.2.1 Risks to seals from bycatch

Bycatch is thought to be the biggest fisheries pressure facing grey seals, although this species appears to be reaching many of its GES targets (Table 4, Appendix 2). The current status of the common seal, which is below target levels, is not thought to be due to bycatch.

While figures for the two seal species are presented together in the BMP, most bycatch observations are for grey seals. Estimations suggest the vast majority of bycatch occurs in ICES divisions 7f, 7e and 7d with tangle and trammel nets. Again, the majority of seal bycatch is associated with static nets, and some bycatch has been associated with the North Sea sandeel fishery (Northridge et al., 2019, Kingston et al., 2021). There are no set “environmental mortality limits” for grey seals (Kingston et al., 2021) meaning assessment against the incidental bycatch target is not possible, however, available data suggest that demersal gears are not significantly contributing to current bycatch levels.

5.3.2.2 Risks to seals from reductions in prey

Risks relating to prey availability for seals have already been discussed in Section 3.1.2.1.

Seals are known to feed on fish species, with gadoids in particular making significant contributions to the diet of seals in Scottish waters. However, seals are considered generalist feeders. They are thought to exhibit weak ecological interactions with specific prey populations, as they consume a variety of species (Dickey-Collas et al., 2014) and can exploit alternative prey choices in response to the reduced abundance of any single prey species.

Foodwebs dynamics in the UK are difficult to predict, but it is likely that the removal of target species at the scale and diversity of demersal fisheries covered by the Demersal FMPs is likely to have direct and indirect impacts on prey available to marine predators. Further work is needed to better understand the impact of prey reduction on seal populations and the ecosystem interactions between fish and higher predators. A collaborative approach between appropriate authorities and ALBs to develop ecosystem modelling approaches will support a better understanding of the potential impacts of prey reduction on seal populations.

5.3.2.3 Conclusions and recommended actions for seals

There is a moderate risk to achieving GES for the biological biodiversity of seals, due to impacts from demersal fishing activities. Although bycatch in static nets is a significant source of mortality for seals, and demersal fisheries may reduce the availability of prey, at their current scales these pressures are not thought to be among the primary drivers for change with respect to achieving GES for seals. However, there are still significant gaps in the available evidence and research is ongoing to understand the drivers of seal population dynamics in Scotland and the UK. As a result, the FMP risk rating is assessed as moderate. Continued monitoring and enhanced data collection and research to address knowledge gaps may allow us to reassess this risk in future.

5.3.3 UK MS Descriptor D1, D4 biological diversity of birds

The objectives and indicators for the descriptor 'D1, D4: Biological Diversity of Seabirds is Maintained' are detailed in Table A4 (Annex 2). Summaries of risks and actions for this descriptor are provided in Tables 1 - 3.

5.3.3.1 Risks to birds from bycatch

To align with UK MS GES targets, fisheries shouldn't compromise the long-term viability of marine bird populations due to incidental bycatch. There shouldn't be significant population decline or distribution changes since 1992 caused by human interventions. Widespread breeding failures in marine birds induced by human activities shouldn't persist for more than three out of six years.

Risks in relation to seabird bycatch in demersal trawls and seines, static nets, and longlines have been discussed in section 3.1.1.2 above. Although demersal trawling and seining does pose some risk, this is likely to be limited and continued monitoring is required to improve our confidence in assessing this risk. Both static nets and longlines pose a significant bycatch risk, and longlining is considered a major source of bycatch mortality for marine birds. Preliminary estimates by Northridge et al. (2020) and Miles et al. (2020) suggest that bycatch mortality of some bird species is at levels that significantly affects populations and is above levels compatible with GES.

5.3.3.2 Risks to birds from reductions in prey

The significance of demersal fish species to protected seabird species has been discussed in Section 3.1.2.2.

5.3.3.3 Conclusions and recommended actions for seabirds

There is a high risk to achieving GES for the biological biodiversity of birds, due to impacts from demersal fishing activities. This rating is primarily driven by risk of bycatch in static net and longline fisheries for birds. Continued monitoring and enhanced data collection and research to address knowledge gaps may allow us to reassess or improve the geographical specificity of this risk rating in future.

5.3.4 UK MS Descriptor D1, D4 biological diversity of fish

The current targets and indicators for 'D1, D4: Biological Diversity of Fish' are outlined in Table A5 (Annex 2). Risks and actions for this descriptor are summarised in Tables 1-3.

While most fishing activities pose inherent high risks to the biological diversity of fish stocks due to non-target bycatch, we are not presenting detailed advice on this descriptor for the Demersal FMPs. This is because the indicator comprises over 100 sensitive species, and further collaborative work is first needed between the relevant government bodies to determine how best to evaluate risks and provide actionable advice at the fishery management level. Given the complexity of interactions between multiple species, fleets, and fishing methods, strategic solutions may be most effective for achieving GES. We will continue engaging with the FMP working group as part of developing a coherent strategy for restoring and protecting biological diversity across fishing activities in the region. In the interim, progress towards the Fisheries Act’s sustainability and precautionary objectives will facilitate steps in the right direction.

5.3.5 UK MS Descriptor D4 foodwebs.

The current targets and indicators for 'D4, Foodwebs' are presented in Table A7 (Annex 2). Risks and actions associated with this descriptor are summarised in Tables 1-3.

We are not presenting comprehensive advice for UK MS Descriptor D4 foodwebs in this advice, as substantial further work is required to determine appropriate actions at the fishery level. The current indicators focus on size and trophic structure of ecological communities, involving complex interactions between multiple stocks and fisheries. Strategic collaboration will be imperative to improve ecosystem models and our understanding of how fishing mortality impacts food web dynamics. Isolated changes within individual fisheries are unlikely to meaningfully contribute to achieving Good Environmental Status for this descriptor. As the FMP progresses towards sustainability and precautionary objectives under the Fisheries Act, this may result in incremental steps towards GES for D4. However, we will continue engaging with government and other research bodies as part of developing a coherent overarching strategy for food web protections in the region. The close involvement of the FMP working group in this strategic development will help align operational and policy objectives regarding D4 moving forward.

5.3.6 UK MS Descriptor D1, D6 seafloor integrity

The current targets and indicator for the Descriptor ‘D1 & D6 seafloor integrity’ are shown in Table A8 (Annex 2). Risks and actions associated with this descriptor are summarised in Tables 1-3.

5.3.6.1 Risks to seafloor integrity from demersal fishing

All mobile demersal gears pose a risk to this descriptor. For the purposes of this advice SNCBs have focussed on the ‘Extent of Physical damage’ indicator as it most closely tied to fisheries pressure (see Table A8, Annex 2). This indicator is shared with OSPAR and is commonly known as ‘BH3’ and will be referred to as such in the current advice.

BH3 is the primary indicator used to assess the level of disturbance from fishing on benthic habitats. The target determines that the level of exposure to pressure (measured on the spatial scale of OSPAR sub-regions) should not result in more than moderate impact/vulnerability of the habitat (dependent on the sensitivity of the habitat to this pressure). The calculations for the BH3 indicator are complex, but essentially fishing effort data is aggregated so that the relative impact of different mobile benthic gears cannot be readily assessed within it. To be able to provide advice, which is meaningful at the scale of an FMP, the way BH3 is currently aggregated and presented needs to be addressed. Natural England is currently working on dis-aggregating the BH3 indicator as a first step in developing specific FMP-relevant advice.

Collaborative working between government, ALBs and regulators to provide more detailed advice on contributions of different mobile demersal gears within the geographic context of FMPs is required. Detailed consideration of mitigation options should extend across different fisheries and draw on a wide range of stakeholder expertise. The UK Marine Strategy Part 3 (Programme of Measures) suggests the drawing together of a Benthic Impact Working Group and this could be a pragmatic option for delivering future advice, including identifying, developing, and trialling possible mitigation or management options, in partnership.

It is not currently thought that fisheries are contributing significantly to the failure of other indicators for this descriptor (e.g., the ‘physical loss of predicted habitats’), but this is largely driven by the lack evidence of fisheries driven effects on the metrics underpinning those indicators. If evidence were to emerge in the future, then further advice may be required.

5.3.6.2 Conclusions and recommended actions for D1, D6 seafloor integrity

There is a high risk to seafloor integrity. However, this indicator looks at impacts across the >12m UK mobile demersal fishing fleet. It does not include impacts from demersal static gears. While these are likely to be lower risk, these gears can abrade the seafloor where weights and ropes make contact and therefore may impact seafloor integrity if operating at a high intensity. Further work is needed to disentangle and quantify impacts from individual fisheries. Strategic work at a broad geographic scale is required to understand the relative impact from this fishery and identify opportunities to reduce/remove risk and understand trade-offs across the UK fishing fleet.

5.3.7 UK MS D10 marine litter

The current targets and indicator for Descriptor ‘D10 Marine litter’ are shown in Table A9 (Annex 2). Risks and actions associated with this descriptor are summarised in Tables 1-3.

5.3.7.1 Risks from marine litter from demersal fishing

Gear specific estimates of rates of abandoned, lost, and discarded gear have low certainty due to a small number of studies and low sample sizes. Risks are highest in static gear fisheries (French et al., 2022) where significant quantities of gear are deployed into the marine environment and left unattended. Mobile gears are a lower risk but may be a source of plastic ropes and netting which contribute to non-biodegradable marine litter when lost, abandoned, or discarded at sea. Abandoned, lost, or discarded fishing gear (ALDFG) is associated with entanglements and ghost fishing, However, fishing litter is likely to be a relatively small component of overall marine litter, therefore fishing measures alone are unlikely to contribute significantly to the achievement of GES. Some gear loss is driven by the spatial conflict between mobile and static fleet sectors, where competition for space leads to interaction between mobile and static fishing gears. FMPs may consider ways in which to mitigate this conflict, if identified, and any associated gear losses.

5.3.7.2 Conclusions and recommended actions for D10 marine litter

There is a moderate risk to marine litter. More robust estimates of ALDFG in the fishery are required.

Improved access to onshore fishing waste disposal/recycling facilities could be achieved through nationwide industry-led waste management schemes and supported by extended producer responsibility schemes to help develop a circular economy. FMPs could consider initiatives to gather relevant data to record and map gear losses in relevant fisheries in order to better understand the levels of risk and establish baselines.

Individual FMPs may be able to identify and develop mitigating measures/technologies to reduce losses and minimise impacts of ghost fishing and entanglements on marine life.

Some gear loss is driven by the spatial conflict between mobile and static fleet sectors, where competition for space leads to interaction between mobile and static fishing gears. FMPs may consider ways in which to mitigate this conflict and any associated gear losses.