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. They have no planktonic phase meaning that populations when exploited take longer to recover, having to travel from other areas.
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 1970's.
Criterion score: 0.5
Whelk populations are largely unknown but their populations vary considerably between areas so stock assessments are required at a local level. Whelks are a particularly vulnerable species and once overfished they can potentially take a long time to recover. UK wide Landings have increased dramatically, doubling in both tonnage and value between 2002 and 2012, and in 2016, ranked third of all landings in England in 2016, worth over 10m pounds. Landings to Cornwall are a very small fraction of this fluctuating between 10 and 40 tonnes per year.
There have been anecdotal accounts of severely over exploited whelk stocks along the coast of England.
Criterion score: 0.75
There is no management on this non-quota fishery in Cornwall except the standard EU minimum size of 45mm. (which according to recent research by Deven and Severn IFCA is likely to be below reproductive size) As its still a relatively un-exploited species in Cornwall it could be argued that the current management is appropriate.
This fishery is beginning to increase in importance particularly in the south east of Cornwall.
Criterion score; 0
The majority of whelks are caught in baited whelk pots. They are often made from recycled plastic oil tanks. The risk to bycatch caused by these pots is generally low: bycatch typically consists of starfish (Asterias rubens) and various crab species (particularly Carcinus maenas). Bycatch are usually caught alive and undamaged and can be returned to the sea immediately. To prevent bycatch, some IFCAs such as EIFCA have mandated escape holes in pots and riddles are used to separate the catch. Endangered, threatened or protected species are rarely caught, though leatherback turtles have very occasionally become entangled in pot ropes. There are a lack of data on these interactions.
Whelk potting is a passive method of fishing: whelks enter the pot when they are attracted by bait. Pots are generally hauled every 1 to 3 days. The pots are laid on the seafloor (on muddy sand, gravel and/ or rocky substrates) in depths of around 10-30 m. 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.
Whelks are important prey for species such as cod, thornback rays, dogfish, bass and crustaceans; their populations have to be maintained to ensure a healthy ecosystem. Removal of whelks by fishing has resulted in decreased populations of hermit crabs in some areas, as large hermits rely on whelk shells for a home.
Since whelk pots are associated with negligible bycatch (includes juveniles, overfished and/or vulnerable or ETP species); but there is a potential for disruption to sensitive habitats, capture method is scored 0.