Shellfish waters
Monitoring Shellfish
Official Controls
Live bivalve molluscs (LBM) are filter feeders known to accumulate contaminants in the marine environment. When LBMs are intended for human consumption, there are official controls in place to ensure that they are safe for consumption before being sold, in addition to the SWPAs designated as ‘protected areas’ as discussed above.
A ‘competent authority’ is responsible for the classification and official controls related to monitoring Classified Shellfish Harvesting Areas (CSHAs). In Scotland the competent authority is Food Standards Scotland (FSS), and Food Standards Agency (FSA) is the competent authority in England.
The Official Controls in (retained) Regulation (EU) 2017/625 (which has been amended post-EU exit) cut across the entire agri-food chain to ensure competent authorities in EU member states are adhering to rigorous and impartial controls. Along with its Delegated and Implementing regulations, it establishes an integrated approach to official control requirements. This ensures the safety of shellfish products across Europe before they are placed on the market.
These controls are summarised by the FSS website; ‘FSS [and FSA] is required, by European legislation, to undertake an extensive programme of Official Control monitoring of LBMs and marine phytoplankton (algae) from LBM harvesting waters. The results of this programme are used to determine whether an area should be open or closed for harvesting depending on the levels of microbiological and chemical contaminants, including marine biotoxins’ (Food Standards Scotland, n.d.).
CSHAs define the waters which are monitored for the above indicators of an unsafe product. CSHAs do not always lie within SWPAs.
Classification of CSHAs is one of the responsibilities of FSS and FSA, measuring the levels of E.coli present per 100g of flesh as laid out in Annex III of the (retained) EU Regulation 853/2004 and Articles 53, 54 and 55 of (retained) Regulation (EU) 2019/627.
Process of classifying CSHAs
Sanitary surveys are required under (retained) EU regulation (2017/625) before classifying a new CSHA, but may not be required under other circumstances. FSS and FSA will determine whether or not one is necessary for the production area. If required, a sanitary survey looks at pollution sources impacting the shellfish harvesting area, and establish the most appropriate ‘representative monitoring point’, as well as determining the most appropriate sampling plan for the area. As these surveys look at pollution sources they are highly relevant for information about continuous and intermittent waste water outfalls located in the vicinity of survey sites (see Waste water and industrial outfalls).
For more information on the process of conducting sanitary surveys and where to find previously published sanitary surveys for Scotland and England, see the FSS website here, or the FSA website here.
The classification of an area is based on E.coli concentrations impacting the actions a harvester must take in order to send their product to the consumer market. Shellfish samples are collected from CSHA sites and a classification is awarded on the basis of the data over the previous 3 years (if insufficient data, 1-year data is sufficient to award classification). Regulation (EU) 2017/625 allows additional, supplementary, harvester samples to be considered in the official monitoring programme for classification.
Classifications are from ‘A’ to ‘C’ with combined classifications ‘A/B’ and ‘B/C’. The full classification criteria and action for each category is outlined in tables on the FSA and FSS websites. The classification criteria and actions are the same for Scotland and England. CSHAs with a classification of ‘A’ are able to send harvested shellfish directly to market, with ‘B’ subject to purification, relaying in Class A area, or need to be cooked by an approved method, and classification ‘C’ subject to relaying for at least 2 months and approved method cooking. Harvesting is not permitted in any area with E.coli numbers above the criteria for classification ‘C’, where there is over 46,000 E. coli/100g of flesh.
The E.coli classification protocol from FSS, and the protocol for classification of shellfish production areas in England from the FSA, contain information about sanitary surveys and the entire classification process.
Solway Classifications
Classifications do not need to be annual, and can be preliminary, provisional, seasonal or even partial years. This can be seen in the 2021/2022 classification of Loch Ryan, where the classification provided is not for the full year 2021/2022, and is instead classified as ‘B’ up to December 2021, then will be classified as ‘A’ Jan to March 2022.
Loch Ryan, Wigtown Bay, Fleet Bay, and Kirkcudbright Bay are CSHAs in the Scottish Solway. Razor shells (Ensis spp.) are the species sampled for E.coli monitoring for all Scottish Solway sites, apart from Loch Ryan where Native Oysters (Ostrea edulis) are sampled. The classifications detailed below cover Scottish SWPAs for the period from 1 Apr 2021 to 31 March 2022.
| Classified Shellfish Harvesting Area |
Species |
Period covering |
Classification |
| Loch Ryan |
Native Oysters (Ostrea edulis) |
2021
2022 (Jan – March) |
B
A |
| Wigtown Bay |
Razors (Ensis spp.) |
2021/2022 |
A |
| Fleet Bay |
Razors (Ensis spp.) |
2021/2022 |
A (Dormant) |
| Kirkcudbright Bay |
Razors (Ensis spp.) |
2021/2022 |
A |
Fleet Bay CSHA is currently ‘dormant’, this may be due to lack of harvesting activity, but other information on sites being labelled as ‘dormant’ are available in part 11 of the FSS protocol for classification, available here.
Classification documents are available on FSS here. The full details of the results of the E.coli monitoring are available on Scotland’s aquaculture website and on the FSS website.
Data for Loch Ryan, Wigtown Bay, Fleet Bay, and Kirkcudbright Bay for biotoxin, microhygiene, phytoplankton monitoring and area classification data are available by clicking on each location through Scotland’s aquaculture website.
Sample dates and specific concentrations of E.coli per 100g of samples are displayed in a simple table and included in a graph with trend lines through the Centre for Environment, Fisheries and Aquaculture (Cefas) for Loch Ryan, Wigtown Bay, Fleet Bay, Kirkcudbright Bay.
In England, FSA 2020- 2021 (1 September 2020 – 31 August 2021) classifications are available here. Silloth- South (Lees Scar) is the only CSHA in the English Solway in 2020/2021. It is classified for mussel (Mytilus spp.) harvesting and has the 2020/2021 classification ‘B’. The Lees Scar ‘B’ classification is also ‘Long Term’ meaning that the area has been stable with compliance over at least 5 years.
Silloth – Dubmill Scar was declassified as of Sept 2020 (Pacific Oysters, Crassostrea gigas). This may be because an insufficient number of samples were received. For class B and C there must be at least 8 samples per year, and 10 for class A classifications. The Dubmill Scar site had 4 samples provided in 2018, no samples in 2019, and 6 in 2020 according to the samples listed in Cefas’s shellfish monitoring results for the site (available here). Prior to declassification Dubmill Scar had been classified as ‘B’ Long Term. Silloth South -Catherinehole Scar is also listed in the 2020-2021 classifications, as a site which is a prohibited area, and must not be harvested or subject to harvesting. Data for the monitoring of Dubmill Scar, and the currently classified Lees Scar are available through Cefas.
Other strands of monitoring
Other strands of the official control programme of monitoring are Biotoxin and Phytoplankton, Chemical contaminant Monitoring Programmes.
As already mentioned, shellfish are filter feeders and are highly susceptible to accumulating marine biotoxins, resulting from feeding on biotoxin producing phytoplankton, and chemical contaminants such as heavy metals, polycyclic aromatic hydrocarbons, and dioxin and dioxin-like PCBs.
Sampling of shellfish flesh is undertaken from fixed monitoring points in CSHAs (and for scallops harvested from unclassified offshore waters at commercial processors). The samples are tested for Paralytic Shellfish Poisoning, Amnesic Shellfish Poisoning, and Lupophillic Shellfish Toxins, to identify if there is an increased risk of shellfish becoming contaminated and being unsafe for consumption. When exceeding the legal limits set by (retained) EU legislation, action is taken to close the harvesting areas through temporary closure notices and, if necessary, warning notices for casual gatherers and the wider community. For more information on biotoxin monitoring in Scotland click here, for more information on biotoxin monitoring in England click here.
Water samples are collected from CSHAs to determine phytoplankton concentrations as some phytoplankton are toxin producing and monitoring can provide an early indication of toxic events. Phytoplanktons monitored include Alexandrium, Dinophysis and Prorocentrum lima, and pseudo-nitzschia.
Where ‘alert’ concentrations are found harvesters can still harvest LBMs but should take the necessary precautions. For more information on phytoplankton monitoring in Scotland click here, for more information on biotoxin monitoring in England click here. Note that according to the FSA and FSS websites (links provided above), the ‘alert’ concentration for Pseudo-nitzschia is three times more (150,000 cells/litre) in England than in Scotland (50,000 cells/litre).
The latest results for biotoxin and phytoplankton monitoring are available for Scotland through the FSS website here, all historic monitoring data (prior to the latest results) is available through Scotland’s Aquaculture website, here. Biotoxin and phytoplankton monitoring results for England can be found through Cefas, available here.
Legislation also requires that CSHAs are monitored for chemical contaminant concentrations due to the potential risk of bio-accumulation. The EU set levels of chemical contaminants are the same in Scotland and England. Levels should not exceed those laid out in (retained) EC Regulation 1881/2006, as amended.
For more information on phytoplankton monitoring in Scotland click here, for more information on biotoxin monitoring in England click here.
Image; Mussels. © N. Coombey/ Solway Firth Partnership.
