Fishing practices adapted in commercial fisheries: review

Literature Review

2.1 Methodology

A systematic literature review was conducted. Literature searches were conducted in Google Scholar, allowing access to both peer-reviewed and grey literature. All searches were carried out between December 2021 and January 2022. The search strings used during the literature review are available in Appendix A.

Searches used Boolean logic to combine terms relating to the fisheries sector and its associated climate change related impacts. Literature searches were restricted to the time period 20102010 to 2021. This produced 210,560 search results in total. Titles of the first 30 results from each search were scanned (n=1820), and abstracts were read for those papers still considered relevant (n=302). Papers found to contain information relating to actions ongoing or taken in Scottish, UK and European fisheries to reduce GHG emissions from the sector and/or to mitigate other fisheries associated climate change impacts were extracted and saved using open-source reference management software Zotero.

Screening by title, abstract and/or executive summary, to exclude references not relevant to the scope of work, included the following exclusion criteria:

• The subject of the publication was not related to the fisheries and/or processing sector;
• Geographic scope (i.e., not based in Scotland, UK or Europe^[5]); and
• The publication did not contain actions that had been taken to reduce GHG emissions, or wider impacts of climate change.

The remaining publications were considered to be of direct relevance to this review and were examined in full to extract the relevant information and to highlight additional sources of information for inclusion (Appendix B). The literature selection process is depicted in Figure 2.1. In addition, references were retained if the publication addressed, or was relevant to mechanisms, by which the fisheries sector could reduce GHG emissions and/or to mitigate other fisheries associated climate change impacts.

Supplementary references were included within the literature review where there was relevance to the project scope, this included a reference from 2022. In order to address the project's aims (set out in Section 1.2), the literature review was focused on Scotland, the UK and Europe. The 25 references included within this study are focused on examples of actions that have been taken to reduce the fisheries sector's impact on climate change within nine European countries (seven EU member states), and within the four UK home nation (Figure 2.2). When looking at these actions, broken down by geographical region (Figure 2.2), the Netherlands was found to have the greatest number of examples (n=3) after England and Scotland (n=7). The cause for the high number of examples within the literature for Scotland and England is likely a factor of the search criteria, which explicitly included both "UK" and "Scotland".

2.2 Actions to mitigate the fishing sector's impact on climate change (2010 – 2021)

The wider capture fisheries sector, including fishing, postharvest processing as well as product distribution is highly energy dependent, focused primarily on the use of fossil fuels (Muir, 2015). For example, Parker et al. (2018) estimates that in 2011, global fisheries consumed around 40 billion litres of fuel and emitted around 179 million tonnes of CO₂e, or around 4 % of the emissions of global food production in that year. By 2016, fishing vessel emissions had risen to 207 million tonnes of CO₂e (Greer et al., 2019), which is around 0.6 % of global CO₂e emissions that year^[6]. However, it is not only fishing vessels, and direct fuel consumption, that contribute to the sectors climate change related impacts. There are a number of other factors within the fishing and seafood industries which contribute to climate change impacts; for example, GHG emissions from seafood transport, processing and storage, or wider ecosystem impacts associated with unsustainable harvest rates, poor selectivity, and habitat damage caused by bottom contacting towed gear.

There is paucity of information in the primary and secondary (i.e., grey) literature of businesses taking actions to mitigate the impacts of fisheries on climate change, predominantly due to such actions being taken for economic, instead of environmental, reasons. For the majority of the fishing sector, where there is an economic incentive to make a change (e.g., reduce fuel use, upgrade engines, introduce new fishing gears), or respond to changing legislation (e.g., decisions prohibiting specific refrigerants), then businesses will react to these stimuli and adapt appropriately to ensure smooth and profitable business operations. In fisheries operations, adaptations such as these, which have the direct goal of improving the businesses profitability, take place continually (known as 'technological creep', Ricci et al., 2022). However, where such actions are taken, these are predominantly in relation to reducing cost rather as per se changes in the role of fishing activities on climate change. Although the indirect result of such changes may be a reduction in GHG or reduced ecosystem impacts, this is not the ultimate reason for the change or response.

The lack of information within the primary and secondary literature on actions taken by the industry that may reduce their impact on climate change, may also be associated with a relative absence of reporting by the fishing industry in peer reviewed or public fora. For the majority of fishing companies, changes in working practices, including those that enhance their ability to compete with the wider industry (and which may indirectly reduce fisheries role in intensifying climate change), will likely be classed as commercially sensitive. It is then highly unlikely that such actions are published, with such information remaining within the confines of the business. Such information will likely only become available when it is not deemed commercially sensitive, usually when such business practices are well known in the industry or do not enhance the businesses' competitive economic activities.

In terms of fisheries management actions, the link between management practices and resilience^[7] of the stocks to climate change 'threats' is often indirect. This is due to changes in management being principally carried out to ensure the sustainability of the industry and fishery, in reaction to short term changes in stock biomass or fishing pressure. Such changes may help to build resilience to the effects of climate change, but also means that any improvement in management can be effectively labelled as an 'action' to build resilience, though is not directly imposed as such. In this respect, there are a myriad of changes that have been undertaken within fisheries management (within Scotland, the UK and wider EU) that may have (or had) indirect effects on the resilience of the respective stocks. Very few examples were returned by the literature review using the pre-determined search strings, however this aspect would benefit from being pursued as a separate piece of work.

To examine and provide a detailed synopsis of the potential actions, taken by the industry and in terms of fisheries management, we focus on eight broad categories of potential change in fisheries. These describe the mechanisms by which GHG emission reductions and wider fisheries induced climate change impacts mitigation can occur. Within each of the eight categories, examples of actions taken to mitigate the impacts of climate change are discussed, along with a description of the actions that are being undertaken in Scotland compared to the wider UK and EU, including possible evidence gaps. These eight categories are set out below:

• Fossil fuel consumption; efforts to reduce fossil fuel consumption and associated GHG emission from fishing vessels.
• Alternative energy; Cleaner energy supply for fish and shellfish processing.
• Selectivity; the use of more selective and efficient methods of fishing to either:
  • Reduce fishing effort (time at sea); or
  • Reduce fuel consumption while fishing.
• Local Markets; better use of local markets for local produces, reducing food miles and associated GHG emissions.
• Reducing waste; efforts to reduce waste/gear loss, thereby reducing marine litter and GHG emissions.
• Refrigerants; measures taken to reduce the contribution of refrigerants to GHG emissions.
• Stock resilience; measures to improve stock resilience to climate change.
• Consumer behaviour; efforts to change consumer behaviour to either:
  • Focus on species that are fished at MSY; or
  • Reduce food miles and associated GHG emissions.

To examine and understand the role of such actions in structuring the Scottish fishing industry, the learnings from the literature review have been utilised to develop and enhance a stakeholder questionnaire (Section 3.2.2). This has been to ensure that responses from Scottish stakeholder's address both the gaps in the literature as well as gaps in the understanding of such actions in Scotland. In addition, by building the questionnaire in a stepwise approach this has served to ground truth initial findings and set these more firmly within the Scottish context.

2.2.1 Fossil fuel consumption

There are a range of actions that fishers can take to reduce fishing vessel fossil fuel consumption and related GHG emissions (Table 2.1). The focus of this section is to describe the physical changes that have been made to fishing vessels in order to increase their fuel efficiency. These changes can be lumped into improving the efficiency of propulsion systems or improving hydrodynamics (e.g., changes to engines, gear boxes, propellers, hull design or antifouling systems). We discuss with examples such changes, and the role of such changes in impacting fuel efficiency.

Below is a range of measures and actions that fishers can take to reduce fishing vessel fossil fuel consumption and related GHG emissions.

(Source: He et al., 2018)

HULL RELATED

Bulbous bow - Action: Retro-fit installation

Fuel saving:

• Low 5%
• High 15%

Hull appendages - Action: Reduce/smooth/align appendages

Fuel saving:

• Low 2%
• High 5%

PROPULSION RELATED

Vessel speed - Action: Reduction

Fuel saving:

• Low 5%
• High 20-30%

Engine - Action: Replacement with new

Fuel saving:

• Low 7%
• High 20%

Engine - Action: Correct design/installation including exhaust

Fuel saving:

• Low
• High 4%

Gearbox and propeller - Action: Replacement

Fuel saving:

• Low 5%
• High 15%

Propeller nuzzle/duct - Action: Install

Fuel saving:

• Low 0%
• High 15 - 20%

Trim and weight - Action: Correction

Fuel saving:

• Low 0%
• High 5%

Fuel meter - Action: Install and keep records

NON-PROPULSION RELATED

Hydraulics - Action: Upgrade pumps and controls

Refrigeration - Action:

• Upgrade compressors and pumps.
• Improve insulation

Heating/cooling, electrical and lighting - Action:

• Utilise waste heat
• Improve insulation

Parasitic loads such as pumps and motors - Action:

• Upgrade controls
• Switch off all above

Fuel saving:

• Low 0.5%
• High 1.5%

Operational awareness - Action: Improve by training and record keeping

Fuel saving:

• High <10%

Propulsion systems (Engines)

Replacing older less efficient engines, to improve the fuel efficiency of fishing vessels and reduce GHG emissions, has been widely used across the UK and the EU. For example, Owen et al. (2019) found that between 2014 – 2020 the EU's European Maritime and Fisheries Fund (EMFF) funded seven engine upgrades on fishing vessels in England to this end. These projects cost £7,842 on average, and where results were reported, led to around 15 to 30 % (30 to 70 litres) reduction in fuel consumption per week. Such upgrades and change in fuel consumption is equivalent to an annual reduction of 4.81 kg CO₂e^[8] emissions for every £1 of EMFF funding (Owen et al., 2019). Such projects, where engines are upgraded, are relatively easy to implement and have a low initial cost. Based on the examples of fishing vessels in England, these predominantly only result in about 90p saved (social cost of carbon^[9]) for every £1 spent over the expected 20-year life span of the new engine (Owen et al., 2019).

Unfortunately, from the publicly available information, it is not possible to determine additional information regarding the vessels that received engine upgrades through EMFF funding (e.g., vessel size or metier). In addition, Owen et al. (2019) report that "the lack of data collection by individual project beneficiaries has made it difficult to quantify progress towards…the targets set by the MMO as a condition of funding", targets that include emissions and fuel use reductions.

It is clear from Scottish government grants such as the "Fishing vessel energy improvements and re-engining grant"^[10] and EMFF project descriptions (made publicly available through the transparency initiative^[11]) that similar re-engining and upgrading has taken place in Scotland. However, the results of these projects, and others like them, have not been made publicly available. This represents a major gap in information and understanding around the actions taken to reduce GHG emissions from the fisheries sector. It is therefore important that such data is made publicly available in order to enhance the understanding of the role of such actions in reducing GHG emissions from the Scottish fishing industry.

Propulsion systems (gearbox and propeller)

One way to measure and improve propulsion efficiency upgrades is a Bollard pull test^[12], which determines the static pull that a vessel is able to employ in operating conditions (El Zaalik et al., 2015). These have been used within the EU to investigate thrust under different modification scenarios, in order to optimise gearing and achieve maximum efficiency (Notti and Sala 2012; Notti et al., 2014). During trials, where a reduction gear box and ducted propeller have been used, fuel consumption has been reduced by up to 15 % (Notti and Sala, 2012). Such modifications, which can be used to improve vessel fuel efficiency, are able to be applied to both contemporary and older vessels.

It is also clear from EMFF project descriptions, made publicly available through the transparency initiative^[13], that propulsion system (i.e., gearbox and propeller) upgrades have taken place in Scotland. However, these projects are few in number and their results, and information on other similar projects, have not been made publicly available. Again, as with understanding changes in engines within the Scottish fleet, this represents a major gap in information on the actions taken to reduce GHG emissions from the fisheries sector.

Hull design

Modification to improve hydrodynamics, and therefore fuel efficiency, is another route that can be taken to reduce GHG emissions from fishing vessels. Generally, this involves either modification to vessel hull design (e.g., the addition of a bulbous bow) or improved antifouling. Changes to the hull design of existing vessels are often relatively costly and inefficient compared to engine refits (Table 2.1), with examples of bulbous bow retrofits from England showing saving of around 1.67 kg CO₂e for every £1 spent (Owen et al., 2019).

Szelangiewicz et al. (2021) found that the addition of a bulbous bow can increase vessel resistance, fuel use and GHG emissions, but at higher speeds this trend is reversed. Therefore, a careful examination of vessel speeds during steaming, deploying gear and during fishing would need to be carried out to determine if such a retrofit would be beneficial to the fishing vessel in question.

Hull length to width ratio also plays a major role in hull resistance, and in general increasing this ratio (i.e., greater length vs width) will reduce resistance (He et al., 2018). Theoretically, the power required for a 12 m vessel could be reduced by 21 % if fishing capacity and width remained equal, but vessel length increased to 14 m (He et al., 2018; Tourret and Pinon, 2008). In the same way, increasing the length of a 17.5 m vessel to 21.5 m would decrease the overall power required by 27 % (He et al., 2018; Tourret and Pinon, 2008). This would suggest that policy and decision makers looking to reduce fishing vessel GHG emissions should incentivise vessels with an optimised length to width ratio. Yet, due to UK and Scottish licencing systems that rely on length-based fisheries management, there is a threshold that keeps vessels below 10 m (Davies et al., 2018). This has resulted in vessels increasing their fishing capacity, partly by increasing width, while remaining below 10 m in length.

A number of existing management measures may also inadvertently disincentivise fuel efficiency, and obscure actions taken to reduce GHG emissions within the fisheries sector. Hull length to width ratio plays a major role in hull resistance, and in general increasing this ratio (i.e., greater length versus width) will reduce resistance (He et al., 2018) and therefore could act as a barrier to reducing fisheries climate related impacts. Yet, due to UK and Scottish licencing systems, that rely on length-based fisheries management, there is currently an incentive to keep vessels below 10 m (Davies et al., 2018). This has resulted in vessels increasing their fishing capacity, partly by increasing width, while remaining below 10 m in length.

Such vessel designs have been associated with vessels being developed for the specific species they are targeting, the suitability of the grounds and their utility; these vessels are not per se designed to produce as low GHG emissions as possible. In this respect, some older vessels have been adapted as a result of fishing technology advances, operational safety, and following full industry consultation where commercial fishing licences were simplified and streamlined to below 10 m and over 10 m in 2017.

With new vessel construction industry naturally looking into operating and design efficiencies, and as new technology is adopted, particularly driven by fuel price and environmental concerns, policy makers should be looking at ways to encourage adoption of those designs/ technologies which have been developed with the purpose of reducing GHG emissions within the fisheries sector but must remain mindful of balancing opportunity and fleet capacity within effort limits.

Antifouling

Increasing hull surface roughness, associated with biofouling, increases the friction resistance of vessels (Hakim et al., 2019). Such increased friction then necessitates the need for more power to move a vessel, resulting in an overall increase in fuel consumption (Hakim et al., 2019; Nama and Akter, 2021). Although antifouling systems are generally inexpensive, compared with other modifications, their operational lifespan is relatively short (Owen et al., 2019; Nama and Akter, 2021). For example, one year following hull cleaning, the high growth of biofouling can result in fuel consumption increasing by 88 % (Nama and Akter, 2021). This serves to highlight the importance of effective biofouling systems if GHG emissions from fishing vessels are to be reduced.

The results and existence of projects aimed at optimising fishing vessel antifouling to reduce GHG emissions within Scotland are not publicly available. It is widely understood that antifouling is ongoing within the fishing fleet, but there is a paucity of specific information expounding how these actions reduce GHG emissions from the fisheries sector.

2.2.2 Alternative energy

Fisheries processing, including food safe storage, requires large amounts of energy. Therefore, if climate change related impacts of the fisheries sector are to be mitigated, there is a need to identify actions that can be taken to optimise energy use and minimise carbon emissions during fish and shellfish processing. Below we provide a synopsis of the range of actions uncovered by the literature review that are being undertaken in UK and elsewhere in Europe to reduce and optimise energy use, which has focused on efficiency in the regulation of energy while also undertaking further use of potential waste from fish processing.

A smart energy cluster model for the Milford Haven industrial site in Wales was published in 2020. This set out how to manage energy use more efficiently, with the push to switch to a predominantly solar energy supply (Alzahrani et al., 2020; Petri et al., 2020). The proposed system would provide cost advantages to local industries, while also providing energy to the fish processing industry and local community. In fact, estimates were that energy supply would only be expected to dip below demand during winter months (Alzahrani et al., 2020; Petri et al., 2020), leading to a reliable and near self-sufficient energy system. Reduction of the carbon intensity of the electricity grid due to interventions in the energy sector (i.e., the increasing generation from renewable sources) should lead to reduced GHG emissions from the fisheries processing sector.

With an estimated 35 % of globally harvested fish and shellfish currently wasted (FAO, 2020), utilising this waste stream represents a major opportunity to reduce the fisheries sector's carbon footprint. Examples of reducing waste could include turning waste to feed for aquaculture. In Finland, there is ongoing work turning fish waste (from processing) into biodiesel. Biodiesel can be considered close to carbon neutral because fish absorb CO₂ in life equivalent to the CO₂ released when fuel is burned. Mikkola and Randell (2016) report that the site in Finland produces around 400 litres^[14] of biodiesel per day, which is mainly used for business operations and powering local buses. Despite this, Mikkola and Randell (2006) noted that production had not been scaled up commercially due to high taxation on biodiesel in line with that of diesel,

Another innovative solution designed to improve energy efficiency comes from Aquapri, an aquaculture and fish processing plant in Denmark. Aquapri makes use of a bespoke ventilation system, implemented as part of a larger energy improvement project in operation since 2015. This cost £523,270^[15] and was self-funded by the plant (Solberg and Brem, 2016). Despite this large initial outlay, including taking nine months to complete, the return on investment was expected to take 2.5 years (Solberg and Brem, 2016).

2.2.3 Selectivity

There are several ways in which increasing the selectivity of fishing gear can act to ameliorate fisheries induced climate change impacts. Below we examine the effect of selectivity in impacting time at sea and fuel consumption while fishing, and show that significant GHG emission reductions can be made with changes to fishing gear.

Reduced fishing effort (time at sea)

Trawls will often discharge their catch on deck, re-deploy their gear, and then tow as the previous catch is graded and stowed. Therefore, increased selectivity is unlikely to affect the time they spend at sea.

For static gear, where the catch is generally sorted as the gear is brought on board, a cleaner catch (i.e., less bycatch) may mean reduced time sorting, with a shorter time between hauls leading to less time at sea overall. However, for stocks fished in UK waters where the potential catch is not limited by a quota system (e.g., crab, lobster), fishers may simply spend the same amount of time at sea, but deploy more gear due to time efficiency savings. Therefore, the overall impact on emissions reductions is unknown. EMFF funded projects in England, aimed at improving pot selectivity, found that unwanted catches with (new) more selective pots were reduced by 10-15 %, with no reported decrease in landings (Owen et al., 2019). It is unclear what effect this had on the fisher's time at sea and fuel consumption.

Real time reporting of data and information between vessels about areas with a high abundance of unwanted species and sizes (hotspots) may be a potential way of supplementing selective fishing gear. Such methods are being examined within the EU project ØBJ FISK (funded within the INTERREG IV project). The ØBJ FISK project investigated how real time reporting, of areas with a high abundance of non-target species, could be used to facilitate shorter area closures (Eliasen and Bichel, 2016). Closures of around 3 weeks were suggested to replace longer term closures currently in place when bycatch ratios cross certain thresholds (Eliasen and Bichel, 2016). Such ability to understand areas of high discard species would allow vessels to continue fishing, whilst avoiding those areas with a high abundance of non-target species. Within Scotland a similar trial was conducted to test a bycatch avoidance APP (Marshall et al., 2021), however the trial has not led to any conclusive results. In both cases the pathway to reduced GHG emissions is opaque, however if vessels are able to have lower fuel intensity (i.e., amount of catch landed for each litre of fuel used – the lower the intensity the higher rate of landings per fuel used) by targeting areas of low bycatch, this may reduce overall GHG emissions.

Reduced fuel consumption while fishing

The fuel consumption of fishing vessels while actively fishing is often considered to be the largest contributor to GHG emissions emitted by fisheries, including those within Scotland. For example, Sandison et al. (2021) found fuel use accounted for nearly 96 % of emissions for the Scottish pelagic fleet. Because one of the biggest financial costs to the industry is also fuel use, there are numerous interconnected benefits to improving fuel efficiency. Efficiency incentivises innovation in vessel design and engine improvement (discussed above, section 2.2.1), but also gear design. Indeed, major net manufacturers have indicated that they have been substantially engaged with their customers to improve net design efficiency, including minimising weight and improving hydrodynamics (Sandison et al., 2021) to promote more fuel-efficient fishing practices.

While towing trawl gear, generally two thirds of the vessel's energy consumption will be related to the additional effort required to tow the gear (He et al., 2018). In fact, just increasing mesh size or using finer diameter twine can lead to reductions in drag (He et al., 2018), and can reduce overall fuel consumption by approximately 18 % (e.g., Parente et al., 2008; Priour, 2009). In 2011, a trawl system in the Danish Baltic Sea cod fishery, utilising larger mesh and lighter gear was developed to optimise trawl gear to reduce drag. This system exchanged 12 mm steel trawl warps for 10 mm Dyneema®^[16], while the whole body of the net, except the codend, was made of 1.4 mm Dyneema® (Hansen and Tørring, 2012). Hansen and Tørring (2012), found that the results of this Dyneema® trawl system included a 40 % reduction in fuel consumption (per kg of cod caught), increased catch per unit effort, and reduced bottom contact and ecological impact (Hansen and Tørring, 2012).

For bottom contacting gears, such as the trawl system trialled in Denmark, reducing bottom contact can have a big effect on fuel efficiency. In England, the Western Fish Producers Organisation (WFPO) recently conducted a trial with Sumwings, which replaced traditional otter doors on a beam trawler out of Brixham, in the south east of England. These new doors were trialled by the WFPO following similar trials in Holland and Belgium that reported 30 % cuts to fuel use (Caslake, 2022). Importantly, results from the WFPO trial found a 42 % reduction in fuel use (with ongoing use, the average reported fuel saving was approximately 30 %) and reduced interaction with the seabed, leading to a 69 % drop in discards of benthic species (Caslake, 2022). Decreased interaction with the seafloor (by up to 84 %) also doubled the expected lifespan of the fishing gear (Caslake, 2022).

A similar example, from the Turkish sea snail beam trawl fishery in the Black Sea, found that improving sledge design reduces resistance, seabed interaction and fuel consumption (Kaykaç et al., 2017). This change was easy and relatively cheap to implement. Pulse trawling was originally trialled to replace the tickler chain beam trawl in the Dutch flatfish fishery, ostensibly aimed at reducing discards and fuel consumption (Van Marlen et al., 2014). This innovation generated fewer fish discards (~57 %) lowered fuel consumption (37 – 49 %), and increased profit for fishermen despite lower landings (Van Marlen et al., 2014). However, pulse trawling has been banned in the UK and EU over concerns of "negative social and environmental impacts" (Kraan et al., 2020), including issues of animal welfare (De Haan et al., 2016) and the injury and mortality of non-target species (Southerland et al., 2016).

Although the examples discussed above highlight the actions that can and are being taken to adapt fishing gear to reduce drag and therefore GHG emissions, there are no examples of such gear change from within Scotland.

2.2.4 Local markets

The impacts of the COVID-19 pandemic and EU-exit have been felt heavily in supply chains across all sectors, including fisheries and seafood. Issues within the supply chain, including a widespread loss of income and additional regulations, have led to difficulties obtaining supplies, logistical disruptions and demand fluctuations (Sengupta at al., 2021). Mitchell et al. (2020) reports a short-term shift towards local markets and production in the food industry following COVID-19, but predict that this change will be short lived. For the UK, this is because the seafood market is heavily reliant on trade with the EU and globally.

However, the impact of EU-exit poses significant issues to the success of the market chain supplying seafood to the UK. The exit of the UK from the EU has the potential to push those EU suppliers marketing their goods within the UK towards greater use of their local markets, avoiding the potential increased tariffs and restrictions associated with exporting goods to the UK (Symes and Phillipson, 2019). This may have potential benefits to the degree of GHG emissions associated with the transport of goods from the EU to the UK, but may also lead to increased loss of goods. This could be due to longer transport routes between the EU and the UK (due to with increased administrative burden and therefore more issues with the transport of goods into the UK). A compounding factor could be an increase in produce being landed in local markets but not being sold, or being sold for a much lower premium (because of the high quantity available) – both will lead to such fisheries showing higher rates of fuel intensity.

There is a trade deficit for fish products in the UK, where consumption has been significantly higher than production by around 366,500 tonnes in 2016, since at least 2000 (Carpenter and Owen, 2018). As a result, without reducing the trade deficit, there is a limit to the food miles that can be cut by increasing the use of local markets. Therefore, within the UK further use of local markets will not be sufficient to cover the seafood needs of the country. In this respect, relying solely on domestic production for Scottish fish consumption is unlikely. Nevertheless, understanding what is being done to make use of local markets for the sale of fish and shellfish could help reduce the GHG emissions associated with their transport. This could form a good starting point for planning how Scotland can make better and more local use of its fisheries produce, which is significant.

2.2.5 Reducing waste

There are two key mechanisms by which decreasing the loss of fishing gear/waste in general can act to reduce the impacts of fisheries induced climate change impacts. These two mechanisms are:

• Functional fishing gear loss, leading to increased direct GHG emissions associated with replacement fishing gear production and transport; and
• Abandoned Lost and Otherwise Discarded Fishing Gear (ALDFG), leading to ghost fishing and a decrease in ecosystem resilience to the effects of climate change.

Reduced loss of functional fishing gear

Although not directly examined within the literature, reducing the rate at which functional fishing gear (i.e., gears that are in use) is lost may indirectly reduce potential GHG emissions. This is due to the potential reduction in the carbon footprint associated with the longer use of fishing gear if not lost. This also could result in lower total gear production (as new gears do not need to be manufactured as readily), including reducing the need for transport of such gears from the manufacturer to the end user. Although not examined within the literature, there are a number of different projects that reduce the number of lost gears, including through retrieval, management space use and gear design to reduce loss.

In Norway the Directorate of Fisheries conducts an annual retrieval project for the recovery of lost gill nets; fishermen can report the location of their fishing nets when the gear is set to improve the chances of recovery (Langedal et al., 2020; Mengo, 2017). Clear gear identification also discourages damaged gear being abandoned or dumped at sea. The project has been successful, with a reported increase of lost gear recovery, but also less incidental damage of gear, as location reporting allows nearby vessels to avoid set gear, minimising the chance of causing damage (Langedal et al., 2020; Mengo, 2017).

A similar location reporting system is being trialled in the Netherlands, where a mobile phone app is used to record the location of gillnets when set, so that other vessels can avoid them. This reduces gear conflict (e.g., mobile gears towing over and moving static gears) and encourages fishermen to leave gaps between nets with enough space for the trawlers to pass. The reported results have been positive and the loss of nets has "declined substantially" since the mobile phone app introduction (Mengo, 2017).

As stated above (section 2.2.3), within the UK, the Sumwing trial by the WFPO has reduced trawl interaction with the seafloor (by up to 84 %). This is due to the gear's smaller footprint than a traditional beam trawl, due to the single foot setup in the centre of the beam (Caslake, 2022). This effectively doubles the expected lifespan of the fishing gear (Caslake, 2022) and therefore reduces the likely increased GHG emissions associated with the manufacture of new gears.

It is understood that the Scottish Government are supporting efforts within the European Committee for Standardization's Standard for Circular Design of Fishing Gear. This is developing standards that are aimed at improving the circular design on fishing gear, which could reduce the GHG emissions associated with gear production. Additionally, there are efforts being made within OSPAR (to which the Scottish government contributes) to link extended producer responsibility efforts to actions in the updates on the Regional Action Plan for Marine Litter (Morag Campbell, Pers. Comm). These efforts are ongoing but the mechanism by which they could reduce GHG emissions from fishing gear production is indirect and unlikely to be realised for some time.

Despite the range of projects being undertaken to increase the lifetime of fishing gears, there is no clear evidence in the literature of actions being undertaken (similar to those above) to reduce gear loss in Scotland. This represents a major gap in information and understanding around the actions taken within Scotland to reduce GHG emissions from the fisheries sector.

Reduced ALDFG

The effect of ALDFG on climate change and its related impacts is generally indirect and is mainly through the impacts of ghost fishing (i.e., the capture and mortality of aquatic fauna in ALDFG). Unfortunately, this mortality is not taken into account in fisheries management plans, so can disrupt stock recovery, potentially having indirect effects on GHG emissions in the fleet, e.g., if stock biomass is depleted then catch per unit effort is generally sub-optimal (i.e., more time, and therefore fuel, is required to catch the same volume of fish).

Between 2010 and 2021 there are many examples of actions taken in Scottish, UK and EU fisheries to incentivise best practice in fishing gear and plastics disposal, which thereby reduce the likelihood that fishers will intentionally abandon plastics or gear at sea (Feary et al., 2020). For example, the Net Regeneration scheme run by Odyssey Innovation^[17] in the South of England collects end-of-life fishing gear for recycling, while in Scotland the Fishing for Litter project, implemented in 2005 and coordinated by KIMO UK^[18], involves 285 vessels and 20 ports participating in the removal and processing of marine litter. At the time of writing (February, 2022), fishing for litter had removed over 1,800 tonnes of rubbish from the ocean, and the project is ongoing in Scotland and across Europe, currently funded in Scotland by Marine Scotland (OSPAR, 2020).

Norway introduced a strategy in 2013 whereby fishing vessels could dispose of waste and marine litter in port without paying an extra fee. Instead, a fixed waste disposal fee is included in the port charge (Mengo, 2017). Sweden implemented a similar 'No-Special-Fee' system, where commercial fishermen can pay a set port fee, allowing the disposal of waste in port. Likewise, the 'Keep the Sea Clean' project in Bohuslän (Sweden) facilitates the collection and recycling of fishing gear and litter caught whilst fishing (Mengo, 2017). Meanwhile, pilot projects have been conducted in Spain to improve waste management on vessels and in harbours. Within this system waste containers were installed on vessels, and recycling points in fishing and navigational docks, facilitating easy participation in best practice gear disposal; as a result, fishers were more likely to do so (Mengo 2017).

In fact, the EU's Port Reception Facilities Directive sets out aims to increase the availability of port reception facilities, in an attempt to mitigate the illegal discharge of waste from ships, including fishing vessels. This was transposed into domestic UK legislation by the "Merchant Shipping (Port Waste Reception Facilities) Regulations 2003 to prevent waste produced on board ships from getting into the sea"^[19]. This requires that Scottish ports provide adequate facilities in each port for the disposal of ship generated waste (including fishing gear). This service should be paid for by the vessels calling at the port irrespective of whether or not they use the service. This should, therefore, discourage the illegal dumping of fishing gear at sea. However, no information was provided on the efficacy of this legislation.

Although the Fishing for Litter project in Scotland facilitates the cost neutral removal of marine litter, which can include end-of-life fishing gear, very little is known about the volume of fishing gear run through the scheme, and once removed, where it ends up (at present the majority is likely to be sent to landfill, as there is little capacity in the EU to recycle non-clean fishing gears). In Addition, during the extensive literature review examples of the Port Reception Facilities Directive^[20] being implemented within the UK and EU were not identified. This represents a gap in the available literature and it would be useful to better understand how this statutory instrument is being implemented to advance best practice fishing gear and marine litter disposal. No information is available in the literature on other projects or attempts to incentivise best practice in fishing gear disposal.

2.2.6 Stock resilience

Climate change combines long-term trends, due to changes in ecosystems, and short-term incidents, due to extreme weather conditions (Bastardie et al., 2022). As a result, adaptation to short-term climatic shocks, which may have demographic impacts as well as distributional impacts to stocks, within fisheries management requires implementing systems that contribute to promoting both long-term ecological and short-term economic resilience (Bastardie et al., 2022). In this respect, fish stocks that are well managed (i.e., above biomass reference points and exploited below mortality reference points) can be more resilient to climate related issues (e.g., extreme weather conditions) (Bastardie et al., 2022). Importantly, management must also include an understanding of the stock distribution. Fish populations will move according to environmental changes, so what may appear to be stock decline could be shifts in stock distribution associated with environmental change (Rijnsdorp, et.al., 2009).

There are many actions that fisheries managers can take to bolster the resilience of stocks to the impacts of climate change. The focus of this section is then to highlight examples of where improved resilience has been achieved, and some of the mechanisms used to improve resilience.

Measures to improve stock resilience through harvest strategies are driven at a regulatory and policy level and the aim is always to reach Maximum Sustainable Yield (MSY^[21]) within a stock. Commercial fish stocks in the waters around Scotland (Figure 2.3) have shown positive progress towards this goal in recent years. For example, in 2020 an estimated 69 % of fish stocks of commercial interest to Scotland were fished at sustainable levels. The figure comes from the SSFI (Sustainability of Fish Stocks Indicator^[22]) which uses the historical ICES estimates of fish mortality (F) and spawning stock biomass (SSB)^[23] to determine whether F < F(msy)^[24] and/or SSB > MSY B(trigger)^[25] for the key commercial stocks of interest to Scotland. The 69 % number for the most recent year (2020) is the overall proportion of these stocks for which F and SSB have been estimated to be within MSY bounds for that year. This represents an increase of 3 % from 2019 and 35 % from 2000. The percentage fished sustainably in 2020 is the highest level recorded since this data collection began (1991) and demonstrates the ongoing recovery of the commercial fish stocks. All years of data are revised every time the series of indicators is updated, which means that for 2018, a revised figure was released based on the most recent data, and this is now 64 % and not 67 % as previously thought (Scottish Government, National Indicator Performance | Sustainability of Fish Stocks Indicator).

It is clear, from the increasing number of stocks fished sustainably within Scottish waters that progress is being made to bring fisheries in line with practices compatible with an MSY approach. However, there is still work to be done to better manage Scotland's fish stocks and in doing so maximise their resilience to the effects of climate change. This represents an opportunity to further integrate fisheries management with an approach that is consistent with meeting MSY for some stocks, and in doing so bolster their resilience to climate change.

In addition, the searches of this literature review have shown that some of the most valuable fish stocks to Scotland (by total landings value) still have undefined reference points, making effective management more difficult. For example, ling (Molva molva) in subareas 3, 4, 6–9, 12, and 14 do not have defined reference points (ICES 2021). This represents a data gap that could undermine efforts to effectively mitigate the effects of climate change on stock resilience through effective management measures.

2.2.7 Refrigerants

The use of specific refrigerants can affect fisheries induced climate change impacts, both through the direct use and then potential release of GHG that are used in refrigerants (i.e., Freon), as well as the fuel (i.e., carbon footprint) of refrigerant units, which can vary substantially in their energy efficiency.

Many refrigerants are over 1000 times more potent as a GHG than carbon dioxide^[26]. This potency is known as global warming potential (GWP^[27]). Since 2020, fluorinated GHGs with a GWP greater than 2500 have been prohibited in Scotland for use in servicing or refilling refrigeration systems^[28]. This is broadly consistent with wider UK and EU regulation. However, there is no other evidence within the literature of actions taken to reduce the contribution of refrigerants to GHG emissions and wider climate related impacts.

In terms of global energy consumption, refrigeration and air-conditioning systems utilised within fisheries (on vessels, as well as in use at landing sites) are associated with high energy use and energy demands (Alzahrani et al., 2020; BIM, 2017; Gephart et al., 2017; Murali et al., 2021). Therefore, improving energy efficiencies in this area could greatly reduce the sectors GHG emissions. According to the UNEP, a shift to best practice cooling technologies globally (across all sectors) could reduce GHG emissions by 38–60 gigatonnes of CO₂ equivalent by 2030^[29].

2.2.8 Consumer behaviour

Sustainable food production is increasingly recognised as significant in public perception (Sala et al., 2017), which is driving large-scale shifts in approaches to consumer behaviour (Salmivaara and Lankoski, 2021). However, systems of production and consumption are intertwined and changes towards sustainability in those systems are therefore co-dependent (McMeekin and Southerton, 2012). Shifting consumer focus onto stocks and fisheries that are well managed and fished sustainably (e.g., below F_MSY with SSB above B_MSY) will incentivise best practice in management and relieve pressure on over-exploited, less resilient stocks.

Eco-labels and initiatives providing consumer information are major mechanisms by which changes to consumer behaviour are facilitated. This is done by providing to the consumer a simple and understandable way to assess a products environmental impact (Sigurdsson et al., 2022). This enables the consumer to make easy distinctions between products that meet verified environmental standards and those that do not (Johnston and Roheim, 2006).

The preference of consumer to buy products with an eco-label is becoming increasingly clear. For example, Menozzi et al. (2020) found that within the UK, consumers were willing to pay a £0.64^[30] premium for eco-labelled fish, which is higher than the average (£0.59 per kg) across the five European countries investigated. This trend holds in Scotland, where it was found that eco-labelled fish products are less likely to be withdrawn from the shelves than those without accreditation, lasting longer even than products labelled as 'Scottish' in origin (Sogn-Grundvåg et al., 2019). For Marine Stewardship Council (MSC) labelled products the risk of being withdrawn from the shelves is 64.7 % lower than non-MSC products (Sogn-Grundvåg et al., 2019).

The MSC is a leading seafood-specific scheme, providing an eco-label for fisheries products which meet set requirements for sustainable fishing^[31]. Although this is not directly concerned with climate change (GHG emissions are not considered within the standard), many of the criteria with which fisheries must comply will have an indirect mitigating effect (e.g., selectivity and stock resilience). Indeed, climate change may become more central to the scheme^[32], as recent presentations by the MSC have reported that climate change is the most concerning environmental issue to consumers^[33].

Actions taken in Scotland to promote eco-labels and to shift consumer behaviour towards more sustainably sourced fish include the promotion of the MSC by Marine Scotland^[34]; initiatives to educate the public about seafood sustainability^[35]; as well as Seafood Scotland's strategy for Scotland's seafood industry, which aims (amongst other things) to "use standards and accreditation to support marketing and improve business performance"^[36].

This builds on other work within the UK and abroad, such as the Marine Conservation Society's Good Fish Guide^[37]. The Good Fish Guide provides information to help consumers understand which species and stocks are sustainable and which are not. Species are rated based on stock status, where it was caught or farmed and how. This is a charity funded project and is freely available to the public via their website and an app.

Examples of actions taken to shift consumer behaviour in Scotland are available in the literature and include measures of how effective these shifts have been. Although, there is controversy surrounding the efficacy of some eco-label schemes^[38] (Wijen and Chiroleu-Assouline, 2019), and there is limited available information regarding the effect of consumer choices on the associated fisheries GHG emissions.

A complete table of interventions identified during the literature review is provided in Appendix B.