King scallop

Pecten maximus

4: OK - Needs improvement How we work out the ratings

What to check for

Location

Wales

Technical location

Atlantic, Northeast, Irish Sea

Caught by

Dredge

Certification

Fishery Improvement Project (FIP)

Rating summary

There is a lot of uncertainty about the status of Welsh king scallop stocks. Based on the available data, there is concern for fishing pressure, but not biomass. The Cardigan Bay fishery is managed using a variety of measures but it is unknown if this is sufficient to sustain the stock. Scallop dredging can be very damaging to seabed habitats and species. There are some protected areas here, but some vulnerable habitats and species remain at risk of being exposed to dredging.Rating last updated November 2023.

Technical consultation summary

There is a lot of uncertainty about the status of Welsh king scallop stocks. Route 2 scoring has been applied to this rating owing to the uncertainty of the data and the lack of reference points for biomass and fishing pressure. King scallops are considered to have high resilience to fishing pressure. The most recent stock assessment was carried out by Bangor University in 2019 using data up to 2016. In Welsh waters, there are three main king scallop grounds: Cardigan Bay, Liverpool Bay, and North Western Llyn Peninsula. Each area has different stock characteristics and differing trends, but Cardigan Bay is the largest population and the main fishing ground. The Cardigan Bay population is showing an overall increase, while densities in Liverpool Bay and the Llyn Peninsula have remained fairly constant at low levels. We conclude that there is no concern for the biomass, but the varying trends indicate the need for precautionary management. There is a wide range of estimates for what catch limits should be. Maximum Sustainable Yield has been estimated at 49 - 1,970 tonnes. The catch in 2016 was 178 tonnes - at the lower end but still above some estimates of MSY. We conclude there is concern for fishing pressure because it is possible that catch rates are above sustainable levels, although the data are very uncertain. The Cardigan Bay fishery is managed using a variety of measures but it is unknown if this is sufficient to sustain the stock. There is no harvest strategy for this fishery. In December 2023, a King Scallop Fishery Management Plan (FMP) was published covering all stocks in English and Welsh waters. It has not yet resulted in any changes to management and therefore has not affected our ratings. Current management focuses on where and when scallop dredging can take place, and what fishing gear can be used, rather than how many scallops can be taken. However, scallop fisheries in Wales do have a number of regulations, including requirements for monitoring. Scallop dredging can be very damaging to seabed habitats and species. There are some protected areas here, but some vulnerable habitats and species remain at risk of being exposed to dredging. The footprint of the dredge fishery is not fully understood, and therefore there is uncertainty about which habitats are affected. A significant area of Cardigan Bay Special Area of Conservation is open to scallop dredging for a limited time each year. The opening of any MPA to dredging is of concern, as it could have impacts on the features it was designated to protect, especially in sites designated to protect seabed features. According to the most recent SAC assessment in 2018, dolphins in this area are considered to be in favourable condition, but the status of their prey species and the habitats that the prey rely on are uncertain. Sandbanks are in Unfavourable condition. Studies have indicated that habitats Cardigan in Bay would recover relatively well from dredging, but they are disputed, partly because the control areas used for comparison had been historically dredged and may not be a good indicator of the full potential for habitat recovery in the area. Bycatch by dredges may also be of concern. They can be a large proportion of the total catch in some areas. Most (around 75%) of the animals that scallop dredges interact with remain on the seafloor and are not recorded in bycatch surveys.

How we worked out this Rating

There is a lot of uncertainty about the status of Welsh king scallop stocks. Based on the available data, there is concern for fishing pressure, but not biomass.Route 2 scoring has been applied to this rating owing to the uncertainty of the data and the lack of reference points for biomass and fishing pressure. King scallops are considered to have high resilience to fishing pressure.The most recent stock assessment was carried out by Bangor University in 2019 using data up to 2016. Eight years of surveys have been conducted by Bangor University between 2012 and 2019. However, there are not yet enough data for stock assessments, as different models show conflicting trends.In Welsh waters, there are three main king scallop grounds: Cardigan Bay, Liverpool Bay, and North Western Llyn Peninsula. Each area has different stock characteristics and differing trends, but Cardigan Bay is the largest population and the main fishing ground. Within Cardigan Bay, some areas are closed to fishing, and there are differences in trends between these and the open areas.From 2012-2016, stock size appears to have been increasing in Cardigan Bay overall, particularly in areas that have been closed to fishing. However, in areas where fishing is still taking place, stock size is decreasing. Meanwhile, in Liverpool Bay and the Llyn Peninsula, densities have remained fairly constant at low levels. As the Cardigan Bay population is showing an overall increase, we conclude that there is no concern for the biomass. However, the conflicting trends indicate the need for precautionary management.There is a wide range of estimates for what catch limits should be. Maximum Sustainable Yield has been estimated at 49 - 1,970 tonnes. The catch in 2016 was 178 tonnes - at the lower end but still above some estimates of MSY. In the parts of Cardigan Bay where dredging is allowed, harvest rates have been described as ‘very high’, with 75% of scallop mortality due to fishing. We conclude there is concern for fishing pressure because it is possible that catch rates are above sustainable levels, although the data are very uncertain.Recruitment of young scallops into the fishery is very variable and depends on weather, climate, habitat suitability, and level of fishing intensity. Before 2019, recruitment was low in the closed areas of Cardigan Bay, but an increase in 2019 may lead to population increases in the future. Where fishing is allowed, a high proportion of the scallops are below the minimum landing size, which suggests that young scallops are coming into the fishery, probably from the closed area. In the Llyn Peninsula, however, most of the scallops are older. This suggests that recruitment is relatively low and the population is vulnerable to overfishing. The age structure was similar in Liverpool Bay until 2019, when higher numbers of small scallops were seen, indicating the possibility of an increase in the population in future.

The Cardigan Bay fishery is managed using a variety of measures but it is unknown if this is sufficient to sustain the stock. There are concerns that scallop dredging within Cardigan Bay Special Area of Conservation will negatively affect the features it was designated to protect.There is no harvest strategy for this fishery. At the time of writing (November 2023), a King Scallop Fishery Management Plan (FMP) is in development. It will be a joint plan between Wales (Welsh Government) and England (Defra), covering all stocks in English and Welsh waters. The details of the plan are not yet known. Until it is in force, it will not affect the rating for this fishery.Current management focuses on where and when scallop dredging can take place, and what fishing gear can be used, rather than how many scallops can be taken. However, scallop fisheries in Wales do have a number of regulations, including requirements for monitoring.Stock size appears to have been increasing in Cardigan Bay overall, but there are declining trends in the Llyn Peninsula and Liverpool. This indicates the need for precautionary management. There is a wide range of estimates for Maximum Sustainable Yield (49 to 1,970 tonnes) and 2016 catch was 178 tonnes. Catch limits, licensing or effort limits could all help to manage fishing pressure on the stock.Management of the fishery is through the Scallop Fishing (Wales) Order 2010 and the Scallop Dredging Operations (Tracking Devices) (Wales) Order 2012. It applies only to king scallops, not queens, and only covers inshore waters (0-12nm). It includes the following measures:Restrictions on where and how scallop dredgers can operate: 0-1 nautical mile: no dredging; 1-3nm: boats below 10 metres with 6 dredges; 3-6nm: 8 dredges; 6-12nm: 14 dredges.Closed season from 1st May - 31st October for all scallop fishing methodsDredges are restricted by limits on frame width, weight, number of belly rings, requirement for a spring-loaded bar, and number and size of teeth.The minimum size of scallop that can be caught is 110mm.Scallop dredgers must use tracking devices that transmit their position every 10 minutes while fishing within 12nm of shore. Further offshore, pings are every 2 hours.Maximum dredge boat engine power of 221 kWWithin 6nm, the Cardigan Bay scallop fishery operates through the use of permits - 27 were issued in 2018. Before permits can be issued, a Habitat Regulations Assessment must be carried out as fishing is taking place within a protected area.In addition, the Western Waters Effort Regime limits how many days large boats (over 15m) can spend dredging for scallops in the Irish Sea.There are 169 Marine Protected Areas (MPAs) in Welsh Waters, covering around 69% of inshore Welsh waters out to 12nm. Some of these areas ban scallop dredging. However, a significant area of Cardigan Bay Special Area of Conservation is open to scallop dredging for a limited time each year. The opening of any MPA to dredging is of concern, as it could have impacts on the features it was designated to protect, especially in sites designated to protect seabed features.The fishery within the SAC is patrolled by the Marine Enforcement Branch. During the 2020/21 fishing season, four serious infringements were detected and investigated.Project UK is implementing Fishery Improvement Projects (FIPs) on twelve UK fisheries that are important to the UK market. This includes dredged scallops around the UK. The FIP began in 2019 and has an end date of April 2024, at which point it should be ready to undergo MSC certification.The FIP has been successful in tackling some issues, including improving understanding of stock boundaries, bycatch and habitat impacts. These outcomes are not inconsiderable. However, there has been very little change to how scallop fishing is carried out, and there is not enough in place to protect scallops from being overfished. For example, there is no harvest strategy that can respond to stock status by reducing fishing pressure when stocks decline. There also appears to have been no change in fishing practices to reduce bycatch or habitat impacts. Therefore, we do not consider the FIP to have addressed all key environmental issues in this fishery, and it does not meet GFG guidelines for application of a FIP Improver score.The annual FIP report from 2024 indicates that it currently is failing on harvest strategy and harvest control rules, which will prevent it from achieving certification. The FIP lists Fishery Management Plans (FMPs) as a delivery mechanism for improvements. The proposed FMP for king scallops in England and Wales does not include a harvest strategy, although it does include a proposal to develop one. An FMP in Northern Ireland is expected to be consulted on in 2024. There are no plans to develop a scallop FMP in Scotland. Given that the FIP will end in April 2024, and no FMPs will be delivering harvest strategies or control rules by that point, we do not consider it possible for this key issue to be addressed within the FIP timescale.More information is here and here.

Scallop dredging can be very damaging to seabed habitats and species. There are some protected areas here, but some vulnerable habitats and species remain at risk of being exposed to dredging.Almost all (over 95%) of king scallop catches around Wales are by dredging, with occasional catches from trawling and potting. The main environmental impact from dredging is its effect on the seabed. This impact varies depending on which habitats the dredging happens on (see below for more details). However, the footprint of the dredge fishery is not fully understood, and therefore there is uncertainty about which habitats are affected.A proportion of Welsh scallop catches are from within Cardigan Bay Special Area of Conservation (SAC), although it is unclear how much. This is a Marine Protected Area (MPA) designated to protect bottlenose dolphins, among other species. According to the most recent SAC assessment in 2018, dolphins in this area are considered to be in favourable condition, but the status of their prey species and the habitats that the prey rely on are uncertain. Reefs (Sabellaria) and sandbanks are also important features of the site. More mapping is needed to understand exactly where these features are, so there is some uncertainty about their condition. There has been a decline in species richness, abundance and diversity for sandbank species, so this feature is in Unfavourable condition.The scallop fishery in the SAC is subject to a Habitats Regulation Assessment which considers the impacts from scallop dredge fishing on the bottlenose dolphin feature. However, the use of bottom towed fishing gear in MPAs, especially sites to protect seabed features, is of concern. Studies have indicated that Cardigan Bay is subject to high levels of natural disturbance from wave action, which suggests that habitats would recover relatively well from dredging. Experiments on the impact of dredging within the SAC supported this conclusion, but are disputed, partly because the control areas used for comparison had been historically dredged and may not be a good indicator of the full potential for habitat recovery in the area.Bycatch by dredges may also be of concern. Non-quota species are allowed to be caught as bycatch in scallop fisheries, as long as they comprise less than 5% of the total catch. A 2019 report, based on 8 years of surveys in Welsh king scallop fishing areas, indicated that catches in Liverpool Bay and the Llyn Peninsula are dominated by bycatch. Cardigan Bay catches are dominated by king scallops, although bycatch can be a significant proportion here as well. The most common species are spider crabs, common starfish, and brown crab. In a recent study, survival rates of dredged brown crabs were low (45% of crabs were dead/ severely damaged; 24% had missing limbs) and they require a lot of energy to repair themselves (which is vital for their growth and the moulting process). Most (around 75%) of the animals that scallop dredges interact with remain on the seafloor and are not recorded in bycatch surveys.To improve monitoring and reporting of fishing activity, MCS would like to see remote electronic monitoring (REM) with cameras implemented, used and enforced. To reduce the impacts of fishing on the marine environment we would like to see a just transition to a complete ban on bottom towed gear in offshore Marine Protected Areas designated to protect the seabed.About scallop dredging:A typical king scallop dredge, known as a Newhaven dredge, is a heavy steel frame with a chainmail net. There is a toothed bar at the front that penetrates the seabed, flipping the scallop into the net. Dredges are connected to a tow bar that travels over the seabed, and there can be up to 20 dredges per bar. The number of dredges and tow bars are limited by the engine power of the vessel, and by various legislation around the UK.On average, global studies estimate that scallop dredging penetrates seabeds by around 6cm, and can reduce community abundance and species richness by 8-12% per dredge pass. Recovery can take months or years, depending on the species affected. The impacts vary, depending on the type of seabed, the species that live there, and the level of natural disturbance from waves and storms. In more disturbed areas, the habitats and species may be faster growing and more easily able to recover. Sheltered and inshore areas are more likely to have slow-growing, delicate species, like maerl, seagrass, horse mussels and seafans. Sandy areas are generally less sensitive and more easily able to recover. Gravelly seabed communities are more susceptible because they are quite stable and therefore more likely to have larger, longer-lived species.Impacts can include:Removal of species from the seabed and reduction of biodiversity. In particular, it can change the composition of the ecosystem towards shorter lived and faster growing species that can more easily recover from dredging.Reduction in the complexity of the seabed, which can reduce the number of suitable habitats on which species can settle.Resuspension of sediments, which can smother species and prevent photosynthesis or filter feeding.

References

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