Whelk, common whelk

Buccinum undatum

Method of production — Caught at sea
Capture method — Pot or creel
Capture area — North East Atlantic (FAO 27)
Stock area — English Channel (West), Bristol Channel
Stock detail — 7e-f: Devon and Severn IFCA District (0-6nm)
Picture of Whelk, common whelk

Sustainability rating four info

Sustainability overview

Updated: May 2020.

Whelk populations in English waters are largely unknown and localised stock assessments are needed. Although there is limited data available on whelk stocks, the data that does exist indicates that there could be concern for biomass levels. There is concern for fishing pressure in most whelk fisheries around the UK, including in Devon and Severn IFCA district, in the Western English Channel. There is little known about the species resilience to fishing pressure and vulnerability, but, the recent and significant increase in exploitation of whelk fisheries alongside the life history characteristics of the species, high larval mortality from urchin predation, occurrence of stocklets in small spatial scales, together suggests whelks are particularly vulnerable to overfishing, and possibly more so for certain localised populations. Some management measures are in place, including a Minimum Conservation Reference Size (MCRS), some licensing regulations, closed fishing areas, gear restrictions and voluntary fishing effort limitations within the district. It is unknown if these measures are sufficient to protect the stock. The MCRS in DSIFCA district will increase to 65mm in November 2020. This matches the Size of Maturity of whelks in a small part of the fishery (Start Bay), but not the rest of the district, and therefore does not prevent exploitation of juvenile and undersized whelks. Further management measures and population monitoring is required, particularly as whelk landings have increased substantially in recent years. Pots generally cause a very low impact to the seabed and bycatch is negligible.

Biology

Whelks are large marine gastropods, or snails, with strong, whitish shells. They are found from Iceland and northern Norway to the Bay of Biscay, and can be locally abundant around the UK except for the Isles of Scilly. They inhabit sandy and muddy areas, although they can be found on gravel and rocky surfaces, down to depths of 1,200 metres.

Whelks mate during autumn and winter and baby whelks emerge in the spring.

Whelks are carnivorous. They scavenge at depths between 3 - 600m. They have an exceptionally acute chemical sensory ability - which enables whelks to be commercially exploited in baited pots.

Whelks are a particularly vulnerable species because they are long-lived (up to about 15 years), mature late (5-7 years) and produce relatively low number of eggs. In addition, they aggregate together, lay their eggs on the seafloor and are easy to catch. Their exceptional acute sense makes it easy to attract them to whelk pots. These factors make them more susceptible to local overfishing, and once overfished, have a slow path to population recovery. This is further exacerbated when few whelks have had a chance to mature, which can lead to stock collapse e.g. in the Dutch Wadden Sea in the mid 1970as.

Stock information

Criterion score: 1 info

There is concern for the stock and fishing pressure is likely to be above sustainable levels.

Availability of UK whelk fishery data is generally quite poor, and the absence of stock assessments has prevented the definition of Total Allowable Catch (TAC) limits.

Whelk (Buccinum undatum) populations around the UK are largely unknown and there have been anecdotal accounts of severely overexploited whelk stocks along the coast of England. Whelks are a particularly vulnerable species and once overfished they can take a long time to recover. Fishing effort for whelks in the UK has been increasing relatively quickly over recent years. Whelk landings in terms of tonnage and value doubled between 2002 and 2012. UK landings increased from 8.4 to 22.7 thousand tonnes between 2003-2016, and were valued at £21.9 million in 2018.

Whelk stocks within Devon and Severn IFCA district have never been formally assessed. The recent increase in exploitation of whelk fisheries within England alongside the sedentary life history characteristics of the species, a high larval mortality from urchin predation, occurrence of stocklets in small spatial scales, together suggests whelks are particularly vulnerable to overfishing, and possibly more so for certain localised populations. Mostly, it has only been within the last few decades that these biological vulnerabilities have been exacerbated, due to the overall (global) increase in demand for whelks, and have highlighted species vulnerabilities to overexploitation.

Ilfracombe and Exmouth are the two main landing ports within the district for the whelk fishing sector, with 533 tonnes worth £640,877 and 302 tonnes worth £328,075 recorded in 2016, respectively. The increase in fishing effort within this fishery is thought to be attributed to an increased demand in the Far East, particularly South Korea. The consistent increase in fishing effort raises concerns over the sustainability of the fishery.

Sea Fisheries Statistics over the last decade indicate that the English landings of whelk (B. undatum) are highest at ports within the Southern, Sussex and Devon and Severn IFCA districts. In 2017, Devon and Severn IFCA annual whelk landings dropped to its lowest recorded level (2008-2017) at <1000 tonnes (live weight), compared to ~2,400 tonnes in 2016. In 2018, landings inclined to 1,155 tonnes (835 tonnes and 320 tonnes, in the South and North coast ports respectively), which was followed by a further decline (18%) in 2019 to 804 tonnes (562.5 tonnes and 241.5 tonnes, in the South and North coast ports respectively). Annual landing fluctuations can be indicative of a boom and bust fishery. MMO landings data from 2014-2016, highlight the district s Ilfracombe port as the 9th ranking port out of the ten IFCA districts, based on whelk landings (tonnage). Ports located on the south coast of England represent 50% of the top ten landing sites for B. undatum in the country.

Management

Criterion score: 0.5 info

There are management measures in place for this fishery, which are partly effective in managing the stock.

Availability of UK whelk fishery data is generally quite poor, and the absence of regional stock assessments has prevented the definition of Total Allowable Catch (TAC) limits. The absence of regional stock assessments presents a number of challenges for management.

The current management measure in place for this fishery is a Minimum Conservation Reference Size (MCRS) of 55mm which was introduced 1st November 2018. A further MCRS increase, to 65mm, will be in force 1st November 2020. MCRS increases have been introduced as a result of Devon and Severn IFCA (DSIFCA) research (2014-2016) to determine whelk Size of Maturity (SOM - the size at which 50% of the population is sexually mature) and the whelk spawning period across the district. The districts research supplemented previous Cefas led research (2012-2013) that estimated SOM in the main fishing grounds across England. Cefas estimates of SOM for all sampled sites except the Solent, indicated that the EU-MCRS of 45mm does virtually nothing to protect spawning stocks. All studies found that SOM in the DSIFCA district was greater than the EU MCRS. Both Cefas research and DSIFCA 2015 report, indicates that the current 55mm and upcoming 65mm MCRS offers insufficient protection to whelk spawning stocks within the district in both the North and South coast. Whelks were found to reach SOM at 75.5 mm in Ilfracombe (North coast) and between 69.2 (males) and 72.4 mm (females) in Exmouth (South coast). DSIFCA most recent report (2016) indicates an MCRS of 65mm would be sufficient to protect breeding stocks in Start Bay on the south coast, yet, this is not reflective of the entire district or the southern coastline.

There are some licensing regulations, closed areas, gear and voluntary effort restrictions within the district, however, it is unknown if these are sufficient management measures to protect the stock. Under DSIFCA s Potting Permit Byelaw, a potting permit is required and outlines the MCRS catch restriction set for whelks within the district. A permit holder is not authorised to remove any whelks or use any container or any other device for the purpose of storing whelks from Knoll Pins area at Lundy Island or Lundy Island No Take Zone. In the estuaries a permit holder or named representative is not authorised to use any pot with an entrance of <85mm in width unless: a) the entrance to the pot at its narrowest point is fitted with a ring constructed of a rigid material and; b) the ring is fitted across the narrowest part of the entrance to the pot and is the same width as the narrowest part of the entrance to the pot. DSIFCA have also signed a Memorandum of Understanding (MoU) and Voluntary Code of Conduct to limit pots within Lyme Bay Reserve to 500 per vessel, with no more than 30 pots attached to each string.

Vessels >12m in length are required to use Vessel Monitoring Systems (VMS) and record and report catch data electronically. Vessels <10m must have a licence and collect data on fishing effort and landings.

DSIFCA report (2019) identifies the breeding season of whelk within the district and has elucidated whelks within the district actively spawn between October and December. DSIFCA has suggested that a closed season during these months may be considered to protect the spawning whelks. This consideration is encouraging but has not yet been enacted. If introduced this measure could support better management alongside an increased MCRS for the stock within the district.

Indeed, several viable management strategies have been suggested by various IFCA districts to protect and rebuild overexploited stocks, including compulsory sorting based on defined length-width relationships, gear and effort constraints (e.g. limits on pot size and quantity), and closed seasons during important reproductive periods. An increase to the current MLS has been suggested as another feasible management measure in numerous studies. Such measures, could support better management of the stock within the districts alongside localised stock assessments.

The Whelk Working Group (WWG) was formed in 2019 to facilitate the exchange of information relating to the common whelk, Buccinum undatum, between Fisheries and Conservation Authorities (IFCAS), other government agencies, fisheries authorities, academics, researchers and others interested in whelk fisheries. WWG aims to help improve and develop the understanding of whelk and look at the advantages of joint working to develop appropriate management. WWG is comprised of representatives from organisations engaged in the provision of evidence, advice and management of the whelk fishery on a national level. The WWG offers encouraging opportunities for future growth of effective whelk management by working together to improve communication, collaboration and consistency.


Both the EU and UK have fishery management measures in place, which can include catch limits, targets for population sizes and fishing mortality, and controls on what fishing gear can be used and where. In the EU, compliance with regulations has been variable, and there are ongoing challenges with implementing some of them. There was a target for fishing to be at Maximum Sustainable Yield by 2020, but this was not achieved. The Landing Obligation (LO), an EU law that the UK has kept after Brexit, requires all fish and shellfish to be landed, even if they are unwanted (over-quota or below minimum size). It aims to promote more selective fishing methods, reduce bycatch, and improve recording of everything that is caught, not just what is wanted. Compliance with the LO is generally poor and actual levels of discards are difficult to quantify using the current fisheries observer programme.

In the UK, it is too early to tell how effective management is, as the Fisheries Act only came into force in January 2021. The Act requires the development of Fisheries Management Plans (FMPs) (replacing EU Multi-Annual Plans) but 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 met
Timeframes for stock recovery
Technologies such as Remote Electronic Monitoring (REM) to support data collection and improve transparency and accountability
Consideration of wider environmental impacts of the fishery

Capture Information

Criterion score: 0.25 info

Whelks are caught by pots in Devon and Severn IFCA district, within the Western English Channel and Bristol Channel.

Whelks in the UK are almost exclusively caught using baited traps, set for approximately 24 hours, as attraction to bait reduces significantly beyond that period. Devon and Seven IFCA whelk fishery use baited whelk pots in subtidal depths between 10-30m. The pots are baited with fish and shellfish and set using a number of pots attached to one string. Once hauled the catch from each pot is passed through a riddle, which is a piece of equipment made of parallel metal bars. The spacing between the bars allows for undersized whelks and bycatch to fall through the bars, collected and returned to the sea. This minimises bycatch of non-target species by filtering catch, whilst retaining the larger whelks. There is some discussion regarding the introduction of a width-based MLS, which may make selection with a riddle more effective, but this is yet to be introduced.

The risk of bycatch from whelk potting is generally low and typically consists of starfish and various crab species, particularly spider crab. Bycatch is normally caught alive and undamaged and can be returned to the sea immediately. Endangered, threatened or protected species (ETP) are rarely caught. Leatherback turtles have been known to become entangled in pot ropes in UK waters, yet this is extremely rare and there is a lack of data on these interactions.

There is potential for potting to disrupt sensitive habitats.

Whelk potting is a passive method of fishing. Whelks enter the pot when they are attracted by the bait. Pots are generally hauled every 1 to 3 days after being laid on the seafloor (on muddy sand, gravel and/or rocky substrates) in depths of around 10-30m. The effect to the seafloor is likely to be insignificant compared with mobile fishing gears. Studies show that the impact on the habitat is insignificant to substantial cumulative damage from mechanical abrasion due to the deployment and retrieval of pots, especially on sessile, slow-growing or friable flora and fauna such as ross coral or sabellaria. Ghost fishing is generally rare.

References

Brown, J., Macfadyen, T., Huntington, J., Magnus and J. Tumilty (2005). Ghost Fishing by Lost Fishing Gear. Final Report to DG Fisheries and Maritime Affairs of the European Commission. Fish/2004/20. Institute for European Environmental Policy / Poseidon Aquatic Resource Management Ltd joint report. Available at https://ieep.eu/uploads/articles/attachments/4a24b509-013d-44ca-b26e-47c8f52e29c4/ghostfishing.pdf?v=63664509699 [Accessed 08.6.2020]

DEFRA (2015). Summary of Evidence on Impacts of Potting on Designated Features pp.16-44, ‘In’ DEFRA (2015) Evidence for Management on Potting Impacts on Designated Features, MMO1086, Final Report November 2015, pp.1-111.

Devon & Severn IFCA (2018). The Whelk Fishery in D&S IFCA’s District. Available at https://www.devonandsevernifca.gov.uk/Environment-and-Research/Research/Molluscan-Research-in-D-S-IFCA-s-District/Whelks [Accessed 27.05.2020]

Devon and Severn IFCA (2019). Devon and Severn IFCA Potting Permit Byelaw. Potting Permit Conditions – 1st August 2019, pp.1-8.

Devon and Severn IFCA (personal communications, June-July, 2020).

FAO (2020). Species Fact Sheets: Buccinum undatum. Available at http://www.fao.org/fishery/species/2659/en [Accessed 22.05.2020]

Lawler, A. (2013). Determination of the Size of Maturity of the Whelk Buccinum undatumin English Waters - Defra project MF0231, DEFRA, pp1-39.

Lyme Bay Fisheries and Conservation Reserve (2020). The MoU and Voluntary Code of Conduct. Available at https://www.lymebayreserve.co.uk/about/the-mou.php [Accessed 27.05.2020]

MRAG (2018). Management recommendations for English non-quota fisheries: Common whelk, Final Report 16th July 2018. Available at https://www.bluemarinefoundation.com/wp-content/uploads/2019/05/MRAG_Final_Whelk_Report.pdf [Accessed 27.05.2020]

Piperpoint, C. (2000). Bycatch of marine turtles in UK and Irish waters. JNCC Report No 310. 32 pp. Available at https://www.researchgate.net/publication/245592683_Bycatch_of_marine_turtles_in_UK_and_Irish_waters [Accessed 26.05.2020]

Science Direct (2020). Buccinum undatum, Shellfish: Commercially Important Molluscs, in Duncan, P. (2003) Encyclopedia of Food Sciences and Nutrition (2nd Ed.). Available at https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/buccinum-undatum {Accessed 22.05.2020]

SeaLifeBase (2020). Waved whelk, Buccinum undatum. Available at https://www.sealifebase.se/summary/Buccinum-undatum.html [Accessed 21.05.2020]

Stephenson, K. (2015). Determination of the Size of Maturity of the Whelk Buccinum undatum within the Devon & Severn IFCA District. Devon and Severn Inshore Fisheries and Conservation Authority Research Report: KS012015, May 2015, pp.2-24.

Stephenson, K. (2016). Determination of the Size of Maturity of the Whelk Buccinum undatum within the Devon & Severn IFCA District Supplementary Report: Start Bay. Devon and Severn Inshore Fisheries and Conservation Authority Research Report: KS012016, March 2016, pp.3-13.

Stephenson, K. (2019). Identifying the Breeding Season of the Whelk Buccinum undatum within the Devon & Severn IFCA’s District Supplementary Report. Devon and Severn Inshore Fisheries and Conservation Authority, May 2019, pp.3-11.