Sanitary Surveys for the States of Guernsey

The Brief

Carcinus were commissioned by the States Of Guernsey’s Office of Environmental Health and Pollution Regulation to conduct Sanitary Surveys of the oyster aquaculture sites around the Bailiwick. Sanitary Surveys of Bivalve Mollusc Production Areas (BMPAs) are required under EU Regulation (EC) 2019/627, which specifies the health conditions and market placing of live bivalve molluscs, tunicates, echinoderms and marine gastropods. These sanitary surveys comprised two parts:

  • A desk-based assessment of the shellfish beds, to determine the principal sources of microbiological and chemical contamination to each harvesting area and to determine where and how sampling should occur to best represent each zone; and
  • A follow up shoreline survey to validate findings of the desk-based study, identify additional sources of contamination and confirm the conclusions of each assessment.

Our Involvement

The initial stage of this project involved producing a desk-based assessment of each harvesting area, through analysis of existing shellfish monitoring data; the locations, volumes and treatment of consented sewage discharges; other point sources such as fluvial inputs, waterbird hotspots, agricultural land use and marinas/harbours and boat moorings.

These data were analysed by our experienced consultants using open-source GIS and statistical software packages, and a concise technical report was issued to the end client.

Screenshot of a land cover map within QGIS.

An example of the land cover data used by our consultants to assess the sources of contamination to the shellfish beds.

Our initial assessments identified many of the main contamination sources to these harvesting areas, however it was deemed necessary to conduct a shoreline survey to confirm these sources and identify any additional ones.

Two carcinus surveyors on site in Herm

Carcinus surveyors on site in Herm.

A carcinus consultant collecting a water sample from a surface outfall.

A Carcinus consultant collecting a water sample from a surface outfall.

The health and safety of our surveyors, clients and members of the public is always a priority, and the ongoing Covid-19 pandemic has only increased the importance of this. To allow our team to travel to Guernsey, it was necessary to apply for a Critical Worker Exemption. Our thanks go to the Critical Travel team at the States of Guernsey for assisting with all our requests, and the Critical Workers in Guernsey for carrying out the tests.

Following the completion of our self-isolation and testing requirements, our surveyors successfully completed the required shoreline surveys, which involved recording the positions and taking water samples from any surface water discharges, riverine inputs, land drainage and noting the presence of other sources of diffuse contamination such as farm animals, aggregations of waterbirds and boat moorings.

These samples were analysed on our behalf by the States’ Analytical Laboratory for the level of E. coli within them. The findings of these surveys will be used to update the sampling plans presented in the initial reports, to determine the best locations for representative monitoring points moving forwards.

Find Out More

If you would like to find out more about the suite of marine and freshwater ecological surveys we can perform, please view our  capability statements, or contact us.

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Environmental Survey | Shellfish Hygiene | Water Quality