Shellfish
FSS is required, by European legislation, to undertake an extensive programme of Official Control monitoring of LBMs and marine phytoplankton (algae) from LBM harvesting waters.
What's on this page:
Food Standards Scotland is the Competent Authority which is responsible for undertaking Official Controls to determine the safety of marine waters used for the harvesting of live bivalve molluscs (LBMs) in Scotland. LBMs include shellfish such as mussels, oysters, clams and cockles.
Retained EU Regulation 2017/625 along with its Delegated and Implementing regulations, establishes an integrated approach to official control requirements – for more information click here
FSS is required 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.
More details of the individual strands of this programme are outlined below:
- Sanitary surveys
- E. coli classification
- Classification documents and protocol
- Biotoxin monitoring
- Phytoplankton monitoring
- Guidance for industry
Weekly shellfish monitoring can be viewed on our Results page.
Shellfish research can be viewed on our Research pages.
Get Biotoxin alerts via Twitter or by text.
Sanitary surveys
Sanitary Surveys are required under retained European legislation relating to official controls on live bivalve molluscs intended for human consumption (Retained EU Regulation 2073/2005). The surveys are intended to provide a thorough assessment of microbiological pollution sources, develop the most representative sampling plan and identify appropriate production area boundaries and a representative monitoring point (RMP), for all new shellfish production areas. The sources and types of microbiological contamination that might affect new and existing shellfish production areas are examined in detail.
More about sanitary surveys
- The following information is reviewed and assessed:
- location and extent of the shellfish production area
- type of shellfishery (species, method of harvest, seasonality of harvest)
- location, type and volume of sewage discharges
- location of river inputs and other potentially contaminated water courses (from OS maps/nautical charts)
- location of harbours and marinas (from OS maps/nautical charts)
- hydrographic and hydrometric data
- existing microbiological data from water quality or shellfish monitoring undertaken in the same area or adjacent areas.
Available information is supplemented by a practical shoreline survey.
The Centre for Environment, Fisheries & Aquaculture Science (Cefas) have previously undertaken sanitary surveys on our behalf since 2007 and have completed over 100 surveys. You can visit the Cefas website for more information. Alternatively, for a copy of any of the reports, electronic or CD, please contact shellfish@fss.scot.
E.coli classification
Food Standards Scotland is responsible for ensuring that shellfish from designated harvesting areas meet the health standards laid down in Retained EU Regulation 853/2004. Classifications are awarded according to the FSS Protocol for Classification and Management of E.coli results. Live bivalve molluscs (LBMs) harvesting areas are classified by monitoring the levels of E.coli in shellfish flesh.
Treatment processes are specified according to the classification status of the area.
Shellfish classification categories and permitted levels of E.coli/100g flesh:
| Category | Classification criteria | Action |
|---|---|---|
| A |
80% of the samples collected during the review period ≤ 230 E.coli/100g of flesh and intravalvular liquid. The remaining 20% of samples ≤ 700 E.Coli/100g of flesh and intravalvular liquid. |
May go directly for human consumption if end product standard met |
| B |
90% of samples collected during review period ≤ 4600 E.coli/100g of the flesh and intravalvular liquid. The remaining 10% of samples ≤ 46 000 E. Coli/100g of flesh and intravalvular liquid. |
Must be subject to purification, relaying in Class A area (to meet Category A requirements) or cooked by an approved method. |
| C |
Samples ≤ 46,000 E.coli/100g of the flesh and intravalvular liquid.
|
Must be subject to relaying for a period of at least 2 months or cooked by an approved method |
|
Above 46,000 E.coli/100g of the flesh and intravalvular liquid. |
|
In addition, there is a legal requirement for food business operators (FBOs) to ensure the shellfish harvested from classified waters are safe to eat. Therefore, before placing shellfish on the market, FBOs must ensure that they comply with the health standards in Annex III of EC Regulations 853/2004 and the Microbiological Criteria adopted under EC Regulation 2073/2005.
The current Classification of Shellfish Harvesting Areas in Scotland document is available here. The document is divided by Local Authority, where the details of each of the classified production areas are specified. Declassified production areas are noted in a separate report at the back of the document.
If you have any queries regarding the contents of these publications, please contact shellfish@fss.scot.
Results of our E.coli monitoring programme can be found on our Results page.
Approved exporting businesses who do not know their TRACES/approval number can find it by following this link: https://www.gov.uk/government/publications/businesses-approved-to-export-to-the-eu
FSS guidance for local authorities on shellfish purification systems is available here.
Shellfish classification documents
For previous years classification documents (prior to 2011), you can visit The National Archive.
Details of the Live Scottish Classification Document (RMP List) can be found following this link.
FSS protocol for classification and management of E. coli results
The E. coli classification protocol outlines the procedure used by Food Standards Scotland to classify shellfish harvesting areas according to the requirements of Retained EU Regulation 2017/625.
Details of the FSS Protocol for the Suspension of Sampling and Prioritisation of Resources During Covid-19 can be found following this link.
The FSS protocol for classification and management of E. coli results outlines the procedure used by Food Standards Scotland (FSS) to classify shellfish harvesting areas according to the requirements of Retained EU Regualtion 2017/625.
Use of Harvester's Own Results
Retained EU Regulation 2017/625 allows for the results of samples collected by harvester to be taken into account for the purposes of OC decision making. These results will only be considered if taken in accordance with an agreed protocol.
Biotoxin monitoring programme
Marine biotoxins, which are produced by certain types of phytoplankton (marine algae), can accumulate in the tissues of filter feeding live bivalve molluscs (LBMs). The consumption of shellfish which are contaminated with these biotoxins can lead to illness, ranging from sickness and diarrhoea to more serious conditions which could require hospital treatment.
The Food Standards Scotland (FSS) official control (OC) monitoring programmes monitor Scotland’s classified production areas for the presence of marine biotoxin producing phytoplankton in waters and marine biotoxins in shellfish flesh. This OC programme identifies when there is an increased risk of shellfish becoming contaminated with biotoxins and when FBOs are required to take appropriate steps to ensure the shellfish they are placing on the market do not contain unsafe levels. When legal regulatory limits of biotoxins in shellfish are breached, FSS and Local Authorities take action to ensure the affected areas are closed to harvesting.
The OC monitoring programme, involves the sampling of shellfish flesh from fixed monitoring points within inshore classified harvesting areas and additional sampling at commercial processors of wild pectinidae (scallops), which have been harvested from unclassified offshore waters. These samples are tested for three groups of biotoxins:
- Paralytic Shellfish Poisoning (PSP) Toxins;
- Amnesic Shellfish Poisoning (ASP) Toxins, and;
- Lipophillic Shellfish Toxins (LTs), which include the toxins responsible for Diarrhetic Shellfish Poisoning (DSP); and Azaspiracid toxins (AZAs)
For more on the effects of these diseases, see our Foodborne Illness page.
In the phytoplankton monitoring programme, water samples are collected from fixed sites within selected harvesting areas and the composition of marine algae identified and enumerated.
Shellfish flesh monitoring
There are approximately 170 classified shellfish production areas in Scotland. These areas are assigned to specific ‘Pods’, where areas grouped together within a ‘Pod’ are considered to share similar hydrographic and environmental characteristics, as well as similar toxin profiles.
For each ’Pod’, one of the areas is assigned representative monitoring point (RMP) status, with the remaining areas being assigned associated harvesting area (AHA) status. For each RMP, a representative shellfish species (usually mussels) is sampled according to a set timetable based on risk assessment. Currently, samples of LBMs are collected from approximately 90 RMPs by FSS authorised shellfish sampling officers (SSOs) and submitted for flesh analysis. These samples are tested for three groups of algal toxins for which maximum permitted levels are set by the EU legislation - amnesic shellfish poisoning toxins (ASP), paralytic shellfish poisoning (PSP) toxins and lipophilic toxins (LTs) which include diarrhetic shellfish poisoning toxins; DSP, pectenotoxins, yessotoxins and azaspiracids.
Biotoxin levels
The maximum permitted levels of biotoxins in shellfish are:
|
Toxin group |
Regulatory level |
|||
|---|---|---|---|---|
| Paralytic shellfish poisoning (PSP) toxins |
800 micrograms (µg) STX equivalents/kg |
|||
| Amnesic shellfish poisoning (ASP) toxins |
20 milligrams (mg) DA/kg |
|||
|
Lipophilic Toxins |
Diarrhetic shellfish poisoning (DSP) toxins and Pectenotoxins (PTXs) |
160 micrograms (µg) OA equivalents/kg | ||
|
Yessotoxins (YTXs) |
3.75 milligram (mg) YTX equivalents/kg | |||
| Azaspiracids (AZAs |
160 micrograms (µg) AZA equivalents/ |
*Biotoxin sampling and testing follows a risk based monitoring frequency for each Pod.
For details of any Temporary Closure Notices (TCN) and/or Warning Notices please contact your Local Authority Environmental Health Officer (EHO).
TCN information can also be accessed through Twitter and by signing up to text alerts:
By text
If you are on the Orange, Vodafone, 02 or 3 networks, text 'follow FSScotBiotoxins' to 86444.
Please check with your mobile provider for information on charges.
If we get natural toxin results OVER the Max Permitted Level (MPL) for biotoxins we will tweet it! Follow FSScotBiotoxins on twitter
The absence of results for a production area does not necessarily mean the area is free of biotoxins. Even when areas are open for harvesting, it remains the responsibility of the FBO to ensure that their products comply with all relevant statutory requirements.
Results of biotoxin monitoring programme can be found on our Results page.
Phytoplankton levels
Water samples are collected from classified production areas and analysed by light microscopy for various species of phytoplankton. Alert level phytoplankton concentrations have been set as per the table below and harvesters should take the necessary precautions if wanting to harvest under alert conditions.
Phytoplankton alert levels set by National Reference Laboratory network:
| Biotoxin | Phytoplankton |
Alert |
|---|---|---|
| PSP (Saxitoxin) | Alexandrium |
Equal to or greater than 40 cells/litre of Alexandrium |
| DSP (Okadaic acid) | Dinophysis and Prorocentrum lima |
Equal to or greater than 100 cells/litre of Dinophysis Equal to or greater than 100 cells/litre of P. lima |
|
ASP (Domoic Acid) |
Pseudo-nitzschia |
Equal to or greater than to 50,000 cells/litre of Pseudo-nitzsch |
During the reporting period, monitoring frequency was set by the FSS as follows:
- weekly for all sites between March and September;
- fortnightly in October
- monthly sampling from November to February in a limited number of selected areas, to reflect the low abundance of phytoplankton in the water column during the winter months.
Managing shellfish toxin risks in the scallop sector
This guidance document provides information intended to assist enforcement officers and food businesses in the scallop sector in order to ensure compliance with toxin standards set out in Regulation (EC) 853/2004. This guidance replaces the official controls for wild pectinidae guidance issued by Food Standards Agency in Scotland in 2004.
Chemical contaminants
Live Bivalve Molluscs (LBMs) feed by filtering plankton from the surrounding water that washes through their habitat. This feeding mechanism can lead to the bio-accumulation of environmental pollutants such as dioxins, polychlorinated biphenyls (PCBs), heavy metals and polycyclic aromatic hydrocarbons (PAHs) from the surrounding waters. EU legislation defines legal limits to ensure the control of these contaminants in a range of foods including shellfish. In accordance with retained EU law, Food Standards Scotland (FSS) manages the Official Controls (OC) chemical contaminants monitoring programme.
In this programme, shellfish flesh samples are collected from classified production areas and analysed for heavy metals, dioxins, PCBs and PAHs. Levels should not exceed those laid out in Retained EU Regulation 1881/2006, as amended.
Please see the reports on Chemical Contaminant Sampling and Analysis of Shellfish from Classified Harvesting Areas for further guidance.
The maximum permitted levels of chemical contaminants in shellfish:
| Contaminant |
Maximum level (Wet weight) |
|---|---|
| Lead | 1.5mg/kg |
| Cadmium | 1.0 mg/kg |
| Mercury | 0.5 mg/kg |
| Polycyclic Aromatic Hydrocarbons |
5.0 µg/kg for Benzo(a)pyrene 30.0 µg/kg for sum of Benzo(a)pyrene, Benzanthacene, Benzo(b)fluoranthene and Chrysene |
| Dioxins and PCBS |
3.5 pg/g sum of dioxins 6.5 pg/g sum of dioxins and dioxin-like PCBs |
For further information regarding harvesting or the interpretation of results, please contact your local authority or shellfish@fss.scot for advice.
For more information on any aspect of shellfish official controls, monitoring and methodology, please contact shellfish@fss.scot
Guidance for industry
Our 'End-product testing for shellfish toxins' leaflet provides food business operators (FBOs) with the information they need to ensure appropriate implementation of end-product testing (EPT) for marine biotoxins in live bivalve molluscs (LBMs). The leaflet also explains how the different biotoxin testing methods work, lists their limitations and describes how they should be used as a part of the wider risk assessment process. Additionally, the document supplies detailed information regarding the current regulatory limits, list of other factors that should be taken into consideration in conjunction with the EPT, as well as a number of case studies – real life examples of situations where EPT results helped FBOs to demonstrate compliance with the regulations and to influence the monitoring programme. In addition, FSS have developed what has become known as ‘traffic light’ guidance for toxin risk management. This is intended to help harvesters and processors manage the naturally occurring toxin risks associated with their products.
Shellfish Toxin End-Product Test (Quick Reference Guide)
End-Product Testing for Shellfish Toxins
Managing Shellfish Toxin Risks: for Harvesters and Processors
Shellfish classification and monitoring industry forum
The SCMIF will enable formal engagement between Food Standards Scotland (FSS) and both the wild and aquaculture bivalve shellfish industry which is subject to classification and monitoring by FSS.
Annual reports
View our shellfish annual reports.
Contact shellfish@fss.scot for annual reports.
For further information about harvesting or the interpretation of results, please contact your local authority.
Biotoxin alerts
By text
If you are on the Orange, Vodafone, 02 or 3 networks, text 'follow FSScotBiotoxins' to 86444.
Please check with your mobile provider for information on charges.
If we get natural toxin results over the Max Permitted Level (MPL) for biotoxins we will tweet it.
In this section
Shellfish results
Our programme of testing shellfish waters in Scotland is known as the Official control monitoring (live bivalve molluscs) programme.
Shellfish Classification and Monitoring Industry Forum
SCMIF will enable formal engagement between FSS and the wild and aquaculture bivalve shellfish industries, which are subject to classification and monitoring by FSS.