Brown crab

This stock is data limited. There is no concern for the biomass and no concern for fishing pressure.The main stock indicator for assessing stock status against reference points (and around which the harvest control roles are based) for brown crab is landings per unit effort (LPUE) which is considered to be an index of stock abundance. LPUE declined in 2012 to the lowest point in the time series, at which point management actions were triggered (the introductions of creel limits and no additional licenses to be issued) under the agreed harvest control rules. LPUE subsequently increased steadily to a peak in 2018. While LPUE declined again in 2019, it was still above the long term average and around the target reference point (TRP) of 1.6. In 2020, it recovered again to a level above the TRP. The mean size of brown crab caught in the Shetland fishery has also been increasing in recent years and remains well above the target size (145mm). As both indicators for the brown crab fishery are around or above the TRPs, additional management measures have not been triggered. Therefore, there is no concern for biomass.There are no reference points available to assess fishing pressure on the stock. Recorded landings of brown crab have fluctuated since 2000 with no obvious trend. Peak landings of 600 tonnes were observed in 2014, but landings then declined and since 2016 have fluctuated around 300 tonnes annually. Therefore, there is no concern for fishing pressure. Brown crab has a low vulnerability to fishing pressure.The principal fishing areas for brown crab in Scotland are the Hebrides, Orkney, Sule, East Coast, Papa and South Minch and landings from these areas accounted for around 80% of the total in recent years. For assessment purposes, the Scottish creel fishing grounds are divided into 12 assessment areas. A key issue is that there is no straightforward way of ageing crabs and regional assessments of crab stocks around Scotland are currently based on length cohort analyses (LCA) and use reported landings data and market sampling length frequencies collected by Marine Scotland Science.

This fishery has been MSC certified since 2012. It is well managed with a pot limit and effective harvest control rules in place.The Shetland brown crab fishery is managed by a regional Regulating Order for Shetland and this is administered through a distinct management body, the Shetland Shellfish Management Organisation (SSMO). SSMO has the powers to enforce submission of catch and specific areas for landings; minimum conservation reference size (MCRS), real time closures of areas, marking of gear and maximum vessel size.In January 2017, SSMO implemented new Harvest Control Rules (HCRs) for the brown crab fishery based on reference points. The HCRs are dependent on whether stock indicators are in the green zone (at or above target reference point (TRP)), in the amber zone (between TRP and limit reference point (LRP)) or in the red zone (below the LRP). The HCRs for the brown crab fishery are as follows:Where the fishery is fluctuating at or around the TRP, no management actions are required.Where any reference points are amber the following management measures shall be considered using a process of expert judgement based on prior knowledge of the fishery, and using relevant context from additional data sources that are available, but not necessarily included as reference points:No new licenses issuesNo additional effort permitted via succession or through replacement vesselsIncreased minimum conservation reference size (MCRS)Spatial closuresTemporal closuresThe listed management measures will be applied individually, or in combination depending in the values associated with the amber status, the duration of the amber status, and the rate of change within the reference points.Where one of the reference points are red the following management measures shall be implemented:Extending fishery closuresImplementation of a research programme and monitoringWhere the limit reference point has been reached the fishery will be closed.Harvest control rules have been used successfully in the fishery. When landings per unit effort (LPUE) of Shetland brown crab declined in 2012, management actions including the introduction of pot limits and a ban on new licenses were triggered under the agreed HCRs. These are effective management measures, as they led to an increase in LPUE in the following years.The SSMO also requires log sheets to be filled in by all vessels in the brown crab fishery. Fishing area, soak time, the type of gear used, the species targeted, the number of pots hauled and the numbers or weight of landed catch must be recorded. In addition, the numbers discarded and the reasons for discarding (e.g. undersized, soft-shelled etc.) and interactions with endangered, threatened and protected (ETP) species must also be recorded. In addition the SSMO log sheets, vessels over 10m length are required under Scottish legislation to complete EU logbooks and vessels under 10m are required to complete FISH1 forms.Additional management measures in place in Shetland include a maximum size of vessel of 17m overall length (unless fishing exclusively for scallops), an overall limit of 600 pots, of which only 240 may target velvet crabs, and a MCRS of 140mm carapace width for brown crabs. Since May 2025, it is now illegal to land a berried (egg-bearing) brown crab in Scotland, in line with the rest of the UK. The Western Waters effort regime limits the number of days at sea that UK vessels over 15 metres fishing for crabs and scallop in ICES Area 7 can have, to keep the fishery within EU effort limits. The number of allowed days are detailed in each vessel's fishing license, and are not transferrable between vessels or years. Uptake is monitored monthly by the Marine Management Organisation and enforced by local fisheries management authorities. In 2021, there was a 44% uptake of the allowance for the crab sector (fishing for Edible/Brown Crab (Cancer Pagurus) and spider crab (Maja Squinado)). However, this is a lower percentage than usual (for example, in 2019, it was 92%), possibly due to supply chain issues caused by the coronavirus pandemic.The UK Fisheries Act came into force in January 2021 and requires the development of Fisheries Management Plans (FMPs). There are no details yet on how and when these will be developed. FMPs have the potential to be very important tools for managing UK fisheries, although data limitations may delay them for some stocks. MCS is keen to see FMPs for all commercially exploited stocks, especially where stocks are depleted, that include:Targets for fishing pressure and biomass, and additional management when those targets are not being metTimeframes for stock recoveryTechnologies such as Remote Electronic Monitoring (REM) to support data collection and improve transparency and accountabilityConsideration of wider environmental impacts of the fishery

Potting, or creeling, for brown crab, has minimal impact on the surrounding environment but may result in the entanglement of whales in this area.Brown crab and European lobster are fished together in a mixed fishery with seasonal and regional variation in target species taking place. The key fishing season for brown crab in the UK takes place from May to December. Crabs are caught in pots, also known as creels, and can be fished individually or as part of a fleet of up to 100 pots, depending on the size of the boat and crew. Pots are portable traps made of wood or steel wire and plastic. The crab is baited into the initial part (the chamber) and moves into the secondary part (the parlour) where it becomes trapped.In brown crab fisheries, there is no legislation or regulation to standardise the type of pot used. They tend to be highly selective as undersized animals can be returned to the sea alive and survival rates for non-target organisms are thought to be high. More than half of the bycatch caught are predicted to survive, although there is little available research to prove this. Measures to further reduce bycatch include the use of escape panels to allow undersize animals and bycatch to escape pots. North Sea cod may be caught as bycatch in this fishery, and they will generally be undersized. There is a legal obligation to release undersized cod.In creel fisheries, there is potential for entanglement of endangered, threatened or protected (ETP) species from the ropes attached to the pots. A report in 2010 estimated that around 7.5km of creel lines would be in Scottish waters throughout most of the year. These creels are targeting crab, lobster and Norway lobster. Whales become entangled in groundline because the rope used is buoyant and floats in loops between pots, rather than lying on the seabed.The main species at risk are minke and humpback whales. A 2022 study has estimated that in Shetland, 27 minke whales and 18 humpback whales have been entangled from 2009-2019 (out of a total of 302 minke whales and 64 humpback whales in Scotland overall). Minke whales entanglements are likely to be acutely fatal, with 84% of entangled minke whales found by fishers being already dead.Marine mammal bycatch reporting requirements were only introduced in the UK in November 2021, so monitoring to date has been poor. From 2021, new conditions introduced for fishing licenses require all bycatch of marine mammals to be reported within 48 hours of the end of the fishing trip. However, whale entanglements will still be underreported if whales break free or animals are caught in abandoned, lost or otherwise discarded fishing gear.Habitat impacts from potting are low but can occur during deployment, soak time or hauling of the pot, impacting the benthic habitat and associated species through contact with the pot or end weight, or by scouring from ropes. Research that has taken place suggests that while some damage does occur, it is unlikely to be significant unless potting intensity is high (defined as approximately 30 pots per 500 square metres). Most damage occurs where traps are set in rocky habitats that are home to corals, sponges, sea whips and other large emergent species. These habitats and species provide nursery areas, refuges from predators and habitat for the settlement of invertebrate spat.In some circumstances, there can be instances of ghost fishing, when lost fishing gear continues to fish and can entangle a variety of species, but this can be minimised by using appropriate gear and release devices.

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