King scallop

Information about Shetland king scallops indicates that the stock is growing, and there is no concern for the biomass or fishing pressure.King scallop fishing in Shetland developed in the 1960s and landings have steadily increased since then. They peaked at around 1,400 tonnes in 2013, followed by a decline, but have since increased back to 1,400t.Route 2 (data limited) scoring has been applied to this rating owing to the lack of reference points for fishing pressure. King scallops are considered to have high resilience to fishing pressure.Stock assessments for scallops in Shetland are carried out by the University of the Highlands and Islands Shetland (UHI Shetland) on behalf of the Shetland Shellfish Management Organisation (SSMO). The most recent stock assessment was published in 2024, using data up to 2022.There is no direct measurement of biomass or fishing pressure. Instead, the health of the stock is indicated by landings per unit of fishing Effort (LPUE), measured as the number of scallops caught per hour of dredging. LPUE has steadily increased since data collection began in 2000, with 2022 showing the highest on record at almost 35. A target has been set for the LPUE (26), and if the stock falls below this level, additional management measures will be triggered. The stock has been above this target since 2014. Therefore, there is no concern for the biomass.There is no recent measurement or indicator of fishing pressure (F) other than landings data. The most recent available measure is from a stock assessment in 2016, which indicated that F was increasing but remained close to the long-term average. MMO data indicates that landings from Shetland between 2018 and 2022 averaged 1,265t. This is higher than the previous (2013-2017) average of 1,167t but close to the 10-year average of 1,216t. Landings in 2022 were 1,461 tonnes - the highest since 2010. However, the level of fishing effort (hours of dredging per year) has stayed constant. As the LPUE suggests that the stock is growing under current levels of catches, we consider there to be no concern for fishing pressure.In past assessments, there were measures of spawning stock biomass (SSB). SSB increased from 2001 to 2012, but then declined to below the target reference point in 2015. Since then, SSB measurements these have been too uncertain to be used. However, scallop surveys have been undertaken since 2007 and there may be a more comprehensive stock assessment by UHI Shetland in future years.The above stock assessment appears to cover inshore Shetland waters (0-6nm), which fall within the jurisdiction of the SSMO. However, a small number of king scallops are caught in the 6-12nm zone. As the stock assessment does not cover this area, it is unclear what the stock trends here would be.

Few appropriate management measures are in place to control scallop fishing in Shetland waters beyond 6nm. Improvements are needed to better understand the stock and the fishery, and protect both scallop stocks and habitats.Almost all (around 99%) of the scallop catch from Shetland is by Scottish vessels, and around 96% of it is caught by dredging. The Shetland Shellfish Management Organisation (SSMO) manages and regulates shellfish fisheries within the 0-6nm zone, but there is no local management for the 6-12nm zone. There is currently no Fishery Management Plan, harvest strategy, or quota.While there is a stock assessment covering the 0-6nm zone, there is nothing currently in place to monitor stocks or the impact of fishing in the 6-12nm zone. Management cannot therefore be responsive to changes in stock, and does not adequately ensure that fishing is controlled to protect the species. It therefore requires considerable improvement.Scallop dredge fisheries in Scotland, including the 6-12nm zone around Shetland, are managed through the Regulation of Scallop Fishing (Scotland) Order 2017. Measures include:A minimum landing size (MLS) of 105mm to protect the breeding stock. Scallops are thought to mature at age 3 or around 80mm, although growth rates vary. Therefore, juveniles are protected. However, it is smaller than the MLS elsewhere in the UK, which is 110mm, and may not adequately protect the breeding stock because scallop reproductivity increases with size.Licenses for those who hadn't fished from 2011-2017 were suspended in 2017 to restrict future effort increases. Vessel owners can only get licenses for replacement vessels if they are not more powerful than the previous vessel, also to restrict future effort increases. In 2021 there were 71 active scallop fishing vessels in Scotland, a reduction from 86 in 2020.A number of areas are closed to scallop dredging to protect the seabed. Seabed protection is important not only to control the impacts of scallop dredging, but to ensure that conditions are suitable for future scallop populations.The number of dredges that boats can use in 0-12nm is limited to 16, increasing to 28 in any other part of the Scottish zone (out to 200nm). There are some exemptions. For example, in the 6-12nm zone, 20 dredges can be used if vessels are using REM. These inshore limits are higher than in Wales, the Isle of Man and England, where the maximum in the 0-6nm zone varies from 8-12, and up to 16 in the 6-12nm zone.Remote Electronic Monitoring (REM) is required on some scallop dredgers. It must have 2 cameras to record setting and hauling fishing gear, winch sensors to record when fishing is happening, and GPS to ping location every 10 seconds. Those that are fishing within 0-6nm with 16 dredges or less (8 per side, each on a towbar of up to 7.5 metres) do not need REM.The Marine Conservation Society responded to the 2014 consultation on the Regulation of Scallop Fishing (Scotland) Order. Our position is that:The minimum landing size should be 110mmA night time curfew in the inshore zone is needed to protect mobile benthic speciesMore spatial closures are needed to better protect scallop grounds and vulnerable habitatsThe footprint of the fishery should be frozen to prevent expansion onto new habitatsIn 2023, the Scottish government confirmed that REM would be made mandatory on all scallop dredge vessels, but had not defined a timeline for this at the time of writing (December 2023). The implementation of REM across the scallop dredge fleet is very positive. MCS believes that Remote Electronic Monitoring (REM) with cameras is one of the most cost-effective tools fisheries managers have for delivering reliable fisheries data and for making informed management decisions. Fully accountable and fully monitored fisheries can improve collaboration and data accuracy, supporting stock recovery, improved selectivity, and minimisation of impacts on marine wildlife and habitats. However, this can only be fully realised if REM is used not only for locations of mapping fishing activity, but also documenting catch and bycatch, especially where there is a risk of impacts on vulnerable species and habitats.In addition, there has been a process since to rollout inshore Vessel Monitoring Systems (i-VMS) on Scottish vessels under 12m since 2020. It was reported that the scallop sector was nearing completion in 2022. This should improve understanding of where dredging is happening in the inshore zone, if and when the data is shared.There have been some suspected instances, and at least one confirmed instance of a scallop dredger operating illegally inside Scottish MPAs. There is no evidence that this is occurring on a large scale but we would strongly encourage commercial buyers to verify the catch locations of their scallops.The stock assessment, harvest strategy and management measures cover the 0-6nm zone only. Scallop fishing in the 6-12nm zone does not appear to be accounted for. A Shetland Regional Inshore Fisheries Group was set up in 2023, joining a network of other non-statutory RIFGs around Scotland that cover the 0-12nm zone. However, they do not have powers to set byelaws or implement management measures. RIFGs aim to "improve the management of inshore fisheries" and "give commercial inshore fishermen a strong voice in wider marine management developments". In Shetland, the RIFG will work with the SSMO and will cover fisheries out to 12nm that are not included in the Shetland regulating order.

Scallop dredging can be very damaging to seabed habitats and species. In Shetland, some vulnerable habitats and species are at risk of being exposed to dredging.Most of Shetland scallop catches are by dredging (around 96%). 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).While most dredging around Shetland appears to take place in the 0-6nm zone, and is covered by the MSC certification, some does happen in the 6-12nm zone. Most work in Shetland has focussed on monitoring and mitigating impacts in the 0-6nm area, and there is little information available about the fishery beyond this. More work is needed to map and protect vulnerable habitats to ensure that 'priority marine features' are not significantly impacted by fishing activity. Scotland’s Marine Assessment 2020 predicts that 80% of the 0-12nm zone of the Shetland Isles is subjected to high levels of disturbance by fishing, although this does include other gears such as trawling.Scottish inshore scallop dredging, including in Shetland’s 6-12nm zone, is less restricted than elsewhere in the UK. In Scotland, each boat can tow up to 20 dredges in the 6-12nm if the vessel is using REM. This is higher than in Wales, the Isle of Man and England, where the maximum is up to 16 dredges.Bycatch by dredges may also be of concern. In the 6-12nm Shetland scallop fishery there is little information about bycatch. 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. Surveys from 2009-2019 have indicated that in Scottish scallop fisheries in general, around 13% of the catch by weight is bycatch, although not all of this is non-quota species. Species commonly encountered include queen scallops, brown crab, whelks and plaice, although differences were observed between the different areas. There is concern for populations of brown crab and whelk in Scotland. However, most (around 75%) of the animals that scallop dredges interact with remain on the seafloor and are not recorded in bycatch surveys.There are a number of Marine Protected Areas (MPAs) in Scottish waters. Some of these are designated to protect the seabed, and are closed to scallop dredging. Others are only partially closed to dredging. There have been some suspected instances, and at least one confirmed instance of a scallop dredger operating illegally inside Scottish MPAs, particularly on the west coast of Scotland. Any scallops known to be caught illegally from an MPA would receive a default red rating on the Good Fish Guide. There is no evidence that this is occurring on a large scale, but we would strongly encourage commercial buyers to verify the catch locations of their scallops.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.