Common periwinkle

Low densities of periwinkle populations are reported in some areas of Northumberland IFCA district. Current levels of periwinkles harvesting do not appear to be negatively impacting populations.Route 2 scoring has been applied to this rating owing to the lack of reference points for fishing pressure and biomass. There are no assessments of the resilience or vulnerability of this species. MCS considers common periwinkle to have medium resilience to fishing pressure, based on several life history parameters. Periwinkles are reported to have low sensitivity to, and high recoverability from, biological removals.There is currently no formal assessment of periwinkle populations (or stocks). Northumberland IFCA conduct surveys at known periwinkle collection sites. The reports (2020-21 and 2022) detail particularity low periwinkle density at Berwick, and low levels at Boulmer, two sites with the highest collection intensities. The primary cause of low densities (e.g. environmental factors, and or collection intensities) at these sites is not confirmed and continued monitoring is underway. The periwinkle populations are surveyed annually at sites of lower concern and more frequently at Berwick and Boulmer. Consequently, there is some concern for biomass.Northumberland IFCA determine that periwinkle harvesting at current levels, in collection hotspots, within the district does not appear to be negatively impacting periwinkle populations. Periwinkle gathering is monitored (2022 onwards) in the annual surveys to detect any changes in effort. As future reports are released any changes in effort within the district should be detailed. Over 3 million periwinkles (estimated economic value £133,982) are thought to be removed from the Berwickshire and North Northumberland Coast (which covers a significant proportion of the NIFCA district) every year.

There are few management measures in place for managing periwinkle populations. All measures are voluntary, and compliance is unknown.Periwinkle fisheries in the UK are generally data poor, although Northumberland IFCA carries out regular population surveys. However, there are no stock assessments, which prevents the definition of catch limits and presents several challenges for management.There are currently no formal regulations in place to control the quantities of periwinkles harvested. It is difficult to accurately assess the size of periwinkle fisheries as they are unregulated, under reported, and often black market in nature, as reported by NIFCA, government reports and others. The scale of IUU (illegal, unregulated and unreported) fishing for periwinkles is unknown.There is no minimum conservation reference size (MCRS) in place for periwinkle(s) caught in UK waters, which could provide protection to immature individuals. Common periwinkles taken below the size of maturity (>15mm in Northumberland IFCA district) would likely not have had the chance to reproduce. Northumberland IFCAs’ voluntary Periwinkle Gathering Code of Conduct asks for a minimum harvest size of 12mm, which offers limited protection to juveniles and level of compliance is unknown.Voluntary periwinkle management measures, Northumberland IFCA district:Conduct minimal habitat disturbance.Sort and return small individuals (<12mm) to area of collection.Recommended use of a sieve or riddle constructed of rigid mesh or bars spaces at least 12mm apart, to separate smaller winkles.Measure periwinkles across the height of the shell from tip to tip.Only collect edible periwinkles and no similar looking species.The measures listed above are detailed within the district's voluntary Periwinkle Gathering Code of Conduct, compliance is unknown.Management of UK periwinkles populations is scarce, but some compulsory measures have been adopted in some regions within England, e.g., closed seasons to protect spawning periwinkle populations, and minimum harvest size of 16mm to protect immature periwinkles.MCS is keen to see publicly available Fishery Management Plans 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, based on the best available scientific evidenceTimeframes for stock recoveryImproved data collection, transparency and accountability, supported by technologies such as Remote Electronic Monitoring (REM)Consideration of wider environmental impacts of the fishery

Periwinkles are gathered by hand on coastal shores. This is a low impact way of catching shellfish. There are rarely any seabed impacts and no bycatch of unwanted species, although disturbances can occur on certain substrates.Periwinkles are found on a variety of intertidal habitats including rocks, stones, and gravels. They can also be found on softer sediment such as mud and sand, they are one of the only Littorinid species to be found on both hard and soft substrates. They are particularly abundant on broken shores or where there are many crevices, congregating near boulders and larger cobbles when on mixed substrates (i.e. exposed bedrock, boulders, cobbles, pebbles, gravel and sand).Hand gathering is the lowest impact way of catching shellfish as there are rarely any seabed impacts and no bycatch of unwanted species. However, it is still important to control these activities and Northumberland IFCAs’ voluntary code of conduct aims to minimise disturbance. In some UK areas, hand gathering is so extensive that beaches have had to be closed to prevent too many shellfish from being taken.The most significant potential impacts to non-target rocky shore dwelling plants and animals from hand gathering activities:Given the nature of periwinkle collection, it has the potential to cause disturbance to nesting or feeding birds.Physical damage from boulder turning and trampling disturbance can cause a reduction in habitat stability and biodiversity.It can adversely impact organisms that depend on upper rock surfaces, such as seaweeds.UK regulations to reduce the impacts of fishing on marine habitats and wider species are under development, in the meantime most EU regulations have been adopted. Under EU legislation, bycatch species should be managed within scientifically defined or, where data isn’t available, suitability precautionary sustainable exploration limits. If stocks fall below a certain threshold, measures can be brought in such as gear limitations (e.g., mesh size or depth of use), time and/or areas closures, and Minimum Conservation Reference Sizes (MCRS).