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)
Stock detail — 7e: Jersey (0-12nm)
Picture of Whelk, common whelk

Sustainability rating four info

Sustainability overview

Updated: May 2020.

Whelk populations in Jersey have shown an overall decline in the past 10 years and the stock is subject to overfishing. 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 predation, occurrence of stocklets in small spatial scales, together suggests whelks are particularly vulnerable to overfishing, and possibly more so for certain localised populations. The current management measures set for the fishery are not effective for managing the stock. Pots generally cause a very low impact to the seabed and bycatch is negligible.


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

The stock is in a poor state and fishing pressure is above sustainable levels.

According to the most recent stock assessment, carried out by Ifremer in 2018, that covers stock in both Jersey and French waters, the spawning biomass (B) was estimated to be at or just above the alert threshold of 0.5 (Bref/Btrigger) at ~0.6. The upper B threshold/Maximum Sustainable Yield (Bmsy) was set at 1. This indicates that the stock is overfished and close to Btrigger, the threshold which fishing mortality must be reduced to restore the stock. Fishing pressure (F) was above the Maximum Sustainable Yield (Fmsy) at ~1.7, also indicating that the stock is subject to overfishing.

The Government of Jerseys Fisheries and Marine Resources Department identified an overall declining trend in the Jersey whelk stock with no significant improvement on catches over the last 10 years. This also indicates B is at or close to Btrigger and stocks are fully fished. The government conduct annual whelk trials to monitor Catch Per Unit Effort (CPUE). The average total CPUE between 2018 and 2020 was 1.57 kg per pot, an increase on the previous 3-year average of 1.44 kg/pot (2015-2017). However, the presence of large whelks (>50mm) declined to 1.22kg/pot (2018-2020), the lowest 3-year average to have been record since the trials began in 1996. In 2020, CPUE for large whelks was 1.063 kg/pot, near the lowest result to have been recorded (1.001 kg/pot in 2015) and significantly below the 1998-2002 average of 2.64 kg. CPUE of small whelks (<50 mm) has displayed a continuous increase since 2016. In 2020, CPUE for small whelks was 0.411 kg/pot, the highest result since 2007 (0.456 kg/pot). This shows some positive signs for future recruitment. Some sites (south-east of Les Minquiers and the east of Jersey) are showing more positive results.

Fishing effort (pot lifts) in 2018 and 2019 were at the highest recorded levels since 2009, and around 2-3 times that of the preceding 4-years (2014-2017). This may be in part due to reduced fishing effort by the Jersey fleet. In 2018, Jersey s total catch was 838.926 tonnes, a 149% catch increase from 2017 (315.303 tonnes) and almost double the volume of the average annual catch over the last 5 years (2015-2019). In 2019, the total catch was 692.559 tonnes, a decrease from 2018.

The Marine Stewardship Council (MSC) certified French whelk fishery is significantly larger (annual volume ~5,000-6,000 tonnes) than the Jersey whelk fishery. The French whelk fishery takes place in both Jersey and French waters but catch reports are unable to identify the proportion of catch taken from Jersey and French waters.


Criterion score: 0.5 info

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

The fishery is managed by a Minimum Landing Size (MLS) which varies between French and Jersey fishing vessels, fishing for whelks within Jersey s Territorial Sea. Jersey s MLS (for Jersey boats) is 50 mm, which was introduced in 2009. This meant an increase of 5 mm from the standard EU-wide MLS of a 45 mm shell height for whelks to which the French boats are regulated by. However, both MLS still provide limited potential for protecting spawning stocks as whelks generally reach sexual maturity >65 mm. Consequently, whelks are being caught before they have had chance to reproduce. Jersey has proposed a review of the MLS that has to date, been rejected by France. Jersey are gathering more data to better determine whelk size at sexual maturity (SOM - the size at which 50% of the population is sexually mature) and seasonality to inform future management decisions. This data will support proposed increases to MLS in 2021 and reviews around closed seasons. Although France does not have an enhanced MLS, it is mandatory for both French and Jersey boats to use graders with a minimum 22mm bar spacing, used for the selection of 50mm whelks. Nonetheless, France are permitted to retain whelks as small as 45mm when sorting.

Jersey’s shared fisheries access scheme with France, permits both French and Jersey fishers to access the whelk fishery in Jersey waters. Both countries have management measures in place for the Jersey whelk fishery, some which apply to both and some which are independent. Jersey s management measures apply to whelks caught by Jersey boats in the 0-12 nautical mile (nm) limit. French measures apply to French boats fishing for whelk outside of Jersey s inshore fishing zone (3 nm limit) and in French waters. All French vessels accessing Jersey waters (3-12 nm) have Marine Stewardship Council accreditation in the whelk fishery, which covers catch in both French and Jersey waters. Jersey and France work together on data collection and have a mollusc working group to inform management for both authorities.

On an annual basis, Jersey meet with marine managers and scientists from Normandy and Brittany, through Mollusc and Crustacean Working Groups in order to share data, discuss management measures and work on joint assessment projects. Management of the whelk fishery outside of the 0-3 nautical mile (nm) limit has been subject to prolonged discussion within the Bay of Granville Agreement.

All Jersey commercial fishing vessels must have a permit (limited up to 15) to fish whelks, vessels over 12 meters are not permitted to enter the fishery. All vessels must keep logbook records, collecting data on fishing effort (number of whelk pots shot during the day), areas fished, and total catch per fishing day. Fishing effort is restricted to a maximum of 900 whelk pots per vessel which must be tagged. All whelks must be put through a grader to protect small whelks. The total number of whelk pots within Jersey s Territorial Sea must not exceed 9,000 (Global pot cap). Vessels may only set whelk pots to fish for whelks in the inshore area of the 3-mile limit on Jersey s East coast between 1st November and 28th February each year. Whelk pots must not be left within this zone outside of this period. Where whelks are caught as by-catch using any type of fishing gear other than whelk pots, the maximum live weight of whelks that may be retained on-board, carried on-board or landed in any day is 5kg.

There are a number of management measures in place for this fishery and sampling data within Jersey waters has revealed a stable sampling return, in recent years. An annual study of whelk (Buccinum undatum) Catch Per Unit Effort (CPUE) is conducted each February by the Jersey Government. Several strings of baited whelk pots are deployed for 24 hours to the North, East and South of Jersey. When the pots are hauled the whelks are graded into €˜small (<MLS) and €˜large (>MLS) and then weighed. The results are used to measure changes in whelk density at key locations. These whelk trials have been run annually since 1996, and contribute to important population monitoring.

Jersey is also a member of the Whelk Working Group (WWG), which was formed in 2019 to facilitate the exchange of information relating to the common whelk, Buccinum undatum, between Fisheries and Conservation Authorities (IFCAS), 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 whelk pots in Jersey s Territorial Sea.

Both French and Jersey vessels catch whelk within Jersey s Territorial Sea, where whelk pots are set in depths between 10-30m. The majority of Jersey boats use traditional larger tub pots and French boats use smaller concrete or steel-based baskets. Whelk pots are baited with fish and shellfish and set using a number of pots attached to one string. It is prohibited to use soft shelled brown crab as bait within Jersey waters when fishing for whelk, and applicable to both French and Jersey fishers. The grading of whelks for size is also mandatory for both Jersey and French boats. Fishers use drum or table type graders, where the spacing between the bars of that grader must be equal to or greater than 22mm. This minimises bycatch of non-target species by filtering catch, whilst retaining the larger whelks (>50mm).

The risk of bycatch from whelk potting is generally low and typically consists of starfish and various crab species particularly the Jersey 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.


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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]