West of Scotland Greater Silver Smelt Fisheries Management Plan

Environmental considerations

Conservation advice

FMPs are subject to legal duties and requirements relating to the protection of the natural environment arising from legislation such as the Habitats Regulations, the Marine Strategy Regulations 2010, and the UK Marine Policy Statement, the Environment Act 2021, Marine and Coastal Access Act 2009, and the Marine (Scotland) Act 2010.

Alongside these requirements, FMPs seek to support a range of other existing environmental policies that focus on enhancing the health of our seas for future generations, restoring marine biodiversity and tackling the causes and impacts of climate change. To support the development of policies aimed at protecting the natural environment, SNCBs provided conservation advice^[15] for the Scottish-led pelagic FMPs.

Advice provided to fisheries policy authorities by SNCBs gives more detail on the risks associated with fishing for species covered by the pelagic FMPs in relation to the protected features of Marine Protected Areas (MPAs), Priority Marine Features (PMFs) for Scotland and UK Marine Strategy (UK MS) Descriptors. Joint advice from JNCC and NatureScot, commissioned by the Scottish Government's Marine Directorate and covering Scottish waters, was received for Pelagic FMPs in Scottish waters as part of a single assessment. Additional joint advice from Natural England and JNCC, commissioned by Defra and covering English waters, was received for the draft blue whiting FMP, Northern Shelf Mackerel FMP, North Sea Greater Silver Smelt FMP, North Sea Herring FMP, and North Sea Horse Mackerel FMP.

Methodology

The SNCBs developed a ‘risk rating’ which is intended to help identify where the greatest impacts of fishing are likely to occur. A three-point scale has been used in the conservation advice: low, moderate and high risk.

• Low risk - An impact pathway exists, but evidence or expert opinion suggests that impacts are minimal or unlikely.
• Moderate risk – Interactions rated as moderate risk typically have an evidenced impact or expert judgment indicates a genuine risk, but factors such as evidence gaps around the scale of impact or exposure to pressures, existing mitigations, or difficulties disentangling impact sources, make it difficult to determine whether the risk is high or low. This precautionary approach to risk assessment is aimed at managing identified risks proactively while acknowledging gaps in current understanding. SNCB advice recommends that FMPs consider enhanced data collection or mitigation options if a moderate risk is identified, taking a proactive approach towards minimising impacts.
• High risk - Interactions identified as high risk are those where available evidence or expert opinion suggests there is an impact at such a scale as is likely to require mitigation.

In contrast to the SNCBs routine advice on environmental sensitivity of distinct habitats or species, the methodology developed specifically for the conservation advice on FMPs provides ‘indicative risk ratings’ on pelagic fisheries in general. These ratings consider the scale of risk associated with the different components of the pelagic fisheries to help identify where the greatest impacts are likely to occur.

The conservation advice provided practical guidance on the most significant risks associated with the interactions between the fishing gear types used to target pelagic fish and the protected features of MPAs, PMFs^[16] (Scottish waters only) and UKMS descriptors.

Summary

The conservation advice highlighted several moderate environmental risks associated with pelagic fisheries in UK waters, including:

• bycatch of fish, marine mammals and birds in the fisheries
• prey reduction, and
• the introduction of marine litter.

Details on the risks to MPAs, PMFs and UKMS descriptors are set out in the below, and more detail can be found in the published conservation advice.

MPAs and PMFs in Scottish Waters

Fisheries contained in the pelagic FMPs have the potential to impact the protected features of MPAs and on PMFs in 2 primary ways;

• through the bycatch of protected features of MPAs/PMFs, and
• the direct (targeted) and indirect (bycatch) removal of prey species on which designated and PMF species depend.

MPAs – risk summary

Evidence suggests that pelagic trawl and purse seine fisheries pose a relatively low risk to the MPA designated marine mammal and fish species features in terms of bycatch^[17], with limited records of bycatch of harbour porpoise, grey seals, basking shark and ‘common’ skate. However, due to low sampling effort, improved evidence is needed to support a low-risk rating for these species.

Several MPA designated bird species features are considered sensitive to bycatch in these fisheries; guillemot, razorbill and cormorant have all been recorded as bycatch in pelagic trawls. In light of limited evidence on bycatch and based on the potential sensitivity to bycatch, expert advice suggests the risk ought to be classed as moderate.

Owing to gaps in the available evidence, the risk rating for bycatch in pelagic fisheries is considered moderate. However, with the introduction and rollout of REM to pelagic fishing vessels in English and Scottish waters, this will enhance the evidence base and could lead to a downgrading of the risk in the future.

This topic is explored further in Policies 3 and 4.

All the fish species managed through the pelagic FMPs are considered prey species for a broad range of predators and as such, are an important part of the marine ecosystem around Scotland. There is good evidence to demonstrate that many of the pelagic species covered in the pelagic FMPs are key prey for many of the designated fish, marine mammal, and seabird features in Scottish MPAs. However, the extent to which features rely on specific pelagic prey species is less clear. As such, the risk rating for pelagic fisheries in Scottish waters regarding removal of important prey species that designated species depend on is considered moderate.

This topic is explored further in Policies 1, 2 and 4.

PMFs (Scotland only)– risk summary

As discussed above for MPA features, pelagic fisheries are not expected to pose a substantial risk of bycatch; however, as evidence gaps remain this has resulted in a precautionary rating of ‘moderate’ for PMF bycatch. Addressing evidence gaps through the collection of REM data, or through enhanced data collection will improve confidence in the assessment of bycatch risks and may result in a downgrading of the risk in the future.

This topic is explored further in Polices 3 and 4.

Several marine mammal and fish PMFs, in addition to those species designated as MPA features, are likely to utilise pelagic species at various life stages as a prey resource. Though they exhibit a variety of foraging strategies, many killer whale groups, including those that visit Scottish waters, are fish-eating specialists, feeding almost exclusively on schooling pelagic fish species such as herring and mackerel. Fin whales feed on small schooling fish species such as herring and sprat. Herring and mackerel are also important prey species for adult porbeagle. Many of the species targeted by fisheries listed under the pelagic FMPs are important prey species for a variety of cetaceans and fishes, including species of conservation interest which are not listed as PMFs, such as the humpback whale. There is a lack of evidence available in relation to the overall ecosystem interactions, and therefore a moderate risk to PMFs (fish, marine mammals) through removal of key prey species in pelagic fisheries is concluded.

This topic is explored further in Policy 4.

UK Marine Strategy Descriptors

Background

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 the Secretary of State, in consultation with the devolved authorities to define the characteristics of Good Environmental Status (GES). In turn the Secretary of State and devolved policy authorities must develop an associated Programme of Measures to deliver this. The UK Marine Strategy Part Three: UK Programme of Measures outlines the actions and initiatives the UK is taking to do this.

The advice focussed only on the most relevant descriptors in terms of risks posed by commercial and recreational fisheries: D1 biodiversity, D3 commercial fish and shellfish, D4 foodwebs, D6 seafloor integrity and D10 marine litter. In the UK Marine Strategy (UK MS) these descriptors are assessed using indicators for each of their constituent ‘ecosystem components.’ The assessment was undertaken by providing advice on the risks to eight descriptor-ecosystem component combinations:

• Cetaceans - D1, D4
• Seals - D1, D4
• Seabirds - D1, D4
• Fish - D1, D4
• Foodwebs - D4
• Seafloor integrity - D1, D6
• Marine litter - D10

The results of an initial consideration of the available evidence and expert opinion of the main risks arising from the fisheries covered by the pelagic FMPs to UK MS Descriptors are summarised below.

Risk summary

There is a moderate risk to achieving GES for the biological diversity of cetaceans, seals, and birds, due to impacts from pelagic fishing activities related to bycatch and through targeted removal of blue whiting, as an important prey species. However, it is important to understand the differences between fishing methods. For trawl vessels, it is thought they have relatively little bycatch risk (although evidence could be improved – as set out already). The lack of evidence to provide a confident assessment of bycatch risk suggests the risk is likely to be moderate. Given the importance of pelagic stocks within the UK marine ecosystem, the potential to impact prey availability needs further consideration for pelagic fisheries.

This topic is explored further as part of Policy 4.

There is a moderate risk to marine litter, with limited evidence available to help disentangle the relative contribution of pelagic fisheries to marine litter. The conservation advice indicates that more robust estimates of abandoned, lost, or discarded fishing gear from pelagic fisheries are required.

The advice also acknowledges that 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. In Scotland a range of actions are undertaken to address issues with marine litter, as set out in the Marine Litter Strategy for Scotland^[18] and these will continue to be delivered as part of a separate programme of work. In addition, the pelagic sector also has designated gear recycling programmes in place.

It should be noted that there is ongoing work with regard to the Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR) to implement the second Regional Action Plan on Marine Litter. This includes action to tackle marine litter from land and sea-based sources, including fishing.

Context and interpretation of the conservation advice^[19]

On bycatch, the moderate risk relates to the limited evidence base and can be classed as a precautionary rating. Given that REM policies for the Scottish pelagic fleet (which are the main pelagic targeting vessels in the UK) are well advanced, and that positive steps are being undertaken elsewhere in the UK to introduce REM, this evidence gap will be addressed, and this is noted within the FMP.

On predator/prey interaction, many pelagic species are integral parts of the wider food web and can often be key predatory and/or prey species. Whilst these interactions between different parts of the food chain are understood, at the present time, ICES do not follow a fully integrated ecosystem-based fisheries assessment model, and therefore fisheries management decisions which include these considerations are not fully possible. Actions to consider this further are contained in the policies and actions section.

On marine litter, there are two main considerations, firstly the risk that fishing in general, (rather than specifically pelagic fishing) presents to marine litter overall, and secondly, gaps in evidence. These two considerations have resulted in a moderate risk rating. However, the fisheries policy authorities do not believe that there is a prevalence or significant risk of marine litter in pelagic fisheries and therefore a specific action on this is not included within the FMP, although positive action is being taken by the UK, through OSPAR, on this, as set out above.

As noted within the FMPs, the pelagic fishing industry is largely regarded as a relatively clean fishery. In general terms, pelagic fish tend to school together as a species, meaning that different species can be targeted by fishing vessels rather than being caught as part of a mixed fishery. This reduces, although doesn’t eliminate, unwanted catches of fish that aren’t the target species. In the UK there is currently a requirement under fishing vessel licence conditions for all fishing vessels operating in UK waters to report any bycatch (incidental mortality or injury) of marine mammals to the MMO within 48 hours of the end of the fishing trip. As of August 2025, no marine mammal bycatch has been reported in Scottish waters to the Marine Management Organisation. Finally, the main fishing fleet targeting pelagic species operates with trawls that rarely come into contact with the seabed, meaning that benthic disturbance is generally not an issue. This is important context in considering the conservation advice and whether any new management action is necessary.

Environmental and ecosystem considerations for pelagic fisheries are also included in the Proposed Fisheries Management Plan for Celtic Sea and Western Channel pelagic species^[20], which should be considered alongside this FMP.

Climate change

Climate change impacts on greater silver smelt

Evidence indicates that climate change is already altering fish distributions, productivity and ecosystem interactions, creating significant challenges for fisheries management systems that have historically been based on relatively stable environmental conditions (Baudron et al., 2020^[21]; Townhill et al., 2023^[22]).

Pelagic fish species generally respond more rapidly and over greater distances to ocean warming than demersal species because their distributions are closely linked to temperature and prey availability. However, the response of individual species depends on biological characteristics such as thermal tolerance, dispersal capacity and life-history traits (Rose, 2005^[23]; Baudron et al., 2020; Montero Serra et al., 2015^[24]; AZTI, 2023^[25]).

Greater silver smelt is more accurately described as a semi-pelagic, benthopelagic or bathypelagic species, forming large aggregations close to the seabed, typically at depths greater than 500 m^[26]. As a deep-water, cold-affinity species, it may be particularly sensitive to environmental changes affecting deeper marine habitats and may respond differently to climate-driven environmental change than more resilient pelagic stocks (Rose, 2005). Its association with deep benthic habitats may limit the availability of suitable refuges as environmental conditions change. Greater silver smelt is also relatively slow-growing and late-maturing compared to many pelagic species, which may reduce its capacity to recover from environmental stressors and periods of poor recruitment. Warming temperatures, declining oxygen concentrations and ocean acidification could reduce the extent or quality of suitable habitat, while increased environmental variability may influence stock distribution, early-life, recruitment success, population resilience and the reliability of stock assessments (MCCIP, 2025^[27]).

However, there is currently limited evidence on the specific impacts of climate change on greater silver smelt, and uncertainty remains high regarding the extent, magnitude and timing of any future effects. Current projections are largely inferred from broader ecological responses observed in other cold-water and deep-water fish species rather than from species-specific studies. See Table 2 below for climate related changes and projected direction for this stock:

Vessel emissions

In addition to the impacts of climate change on GSS and the fisheries that interact with the species, it is important to consider the contribution of fishing activity to greenhouse gas emissions and the need for all sectors to meet net zero targets. The UK policy authorities have different targets relating to climate change and are developing plans to support the drive towards net zero.

The fishing sector contributes to greenhouse gas emissions primarily through fuel use by fishing vessels, the use of refrigerants, and the transport and distribution of seafood products (Engelhard et al., 2022^[28]). At UK level, fuel use from all fishing activity contributed an estimated 467 kt CO₂e in 2024—representing around 0.12% of total UK territorial emissions (378 Mt CO₂e) and 0.43% of domestic transport emissions (109 Mt CO₂e), and equivalent to about 1.1% of agricultural emissions (41.0 Mt CO₂e).

Although the GSS is present in UK waters, the stock is of relatively low economic importance to UK fisheries and UK ports and is primarily targeted by EU vessels as well as licensed Norwegian midwater and bottom trawlers.

While the direct contribution of the GSS fishery is insignificant, consideration of overarching fisheries emissions reduction and fuel efficiency remains relevant as part of wider efforts to support a sustainable, economically viable and climate-resilient fishing sector.

The UK and Norwegian^{[29] [30]} fishing fleets have broadly similar annual emissions; each estimated at around 0.8-1.1 million tonnes of CO₂/CO₂e per year. In comparison, between 2015-2019 the total emissions from EU fishing fleets were approximately 7.3 million tonnes CO₂e annually (Engelhard et al., 2022). While the UK ranked fourth among EU fishing nations for total fishing-vessel emissions, Norway's emissions appear comparable to those of the UK.

Long term considerations

Climate change is increasing uncertainty in the distribution, productivity and management of pelagic and semi-pelagic fish stocks. As a deep-water, cold-affinity species, greater silver smelt may be vulnerable to changes in habitat suitability associated with ocean warming, deoxygenation and ocean acidification. However, evidence on climate-driven impacts on greater silver smelt remains limited, and significant uncertainty exists regarding the magnitude and timing of future effects. This uncertainty reinforces the need for adaptive, evidence-led fisheries management and continued monitoring of stock dynamics and distribution.

To support delivery of the climate change objective in the 2020 Act, as well as of national strategies such as Scotland’s Fisheries Management Strategy, the fisheries policy authorities will work in partnership with stakeholders to support fisheries in the drive to net zero and consider where and how we need to adapt our approaches to take account of the impacts of climate change.

The FMPs will be reviewed and revised as research into climate change impacts develops and new methods to address challenges from climate change become available.