Scottish Shellfish Farm Production Survey 2019

Health Influences on the Industry

In accordance with Council Directive 2006/88/EC, a risk based surveillance programme targeting 59 shellfish site inspections was undertaken during 2019. On these visits, facilities, stock health, bio-security measures plans, movement records and details required for authorisation were checked. Diagnostic samples were taken from 4 sites. Statutory samples were taken from 5 sites as part of an investigation following notification of the suspicion of the presence of Bonamia ostreae.

Movement restrictions placed due to confirmation of the presence of Bonamia ostreae, remained in force in Loch Sunart, Highland and in West Loch Tarbert, Argyll during 2019. In addition, movement restrictions were placed on the Dornoch Firth, Highland and an area covering the Lynn of Lorne, Loch Creran and Loch Etive, Strathclyde following confirmation of the presence of Bonamia ostreae. Movement restrictions covering these areas prevent the relaying of native oyster from them (see Appendix 3 for maps of areas under movement restrictions). Approved zone status for bonamiasis, marteiliasis and Ostreid Herpes Virus-1 Microvariant (OsHV-1 µvar) continued to protect the health of both wild and farmed susceptible shellfish stocks for the remainder of Scotland's waters (https://www.gov.scot/policies/fish-health-inspectorate/movement-restrictions-on-fish-and-shellfish/).

Most of the reported mortalities during 2019 were attributed to: predation from wild ducks, starfish, crabs and oystercatchers; fouling by sea squirts; adverse weather conditions including storms and temperature extremes; damage due to grading and handling and from natural causes. Reports of high, unexplained shellfish mortalities generated three shellfish diagnostic cases during 2019, at sites holding Pacific oysters. Results of diagnostic investigations showed no association with listed (notifiable) diseases. It is the responsibility of shellfish farmers to inform Marine Scotland of any abnormal or unexplained shellfish mortality on their sites (see guidance on shellfish mortality in Appendix 1).

In 2019 there was a continued demand for imported mussel and Pacific oyster spat in Scotland. The industry should be aware of the increased disease risk with the introduction, movement and deposit of stock on site and the importance of ensuring good bio-security practices when sourcing shellfish from other areas. In addition, consignments imported from outside Great Britain are required to be accompanied by a health certificate.

The whole coastline of Great Britain is recognised as free from infection with Marteilia refringens although there are movement restrictions in place on the River Tamar in Cornwall and Devon. Guernsey, Jersey, Herm and the Isle of Man are all recognised as Marteilia refringens free areas. The whole coastline of Northern Ireland is recognised as free from Marteilia refringens apart from Belfast Lough and Dundrum Bay.

The whole coastline of Great Britain is recognised as free from infection with Bonamia ostreae except the following areas which are covered by movement restrictions:

• the south coast of Cornwall from Lizard to Start Point;
• the coast of Dorset, Hampshire and Sussex from Portland Bill to Selsey Bill;
• the area along the coast of North Kent and Essex from North Foreland to Felixstowe;
• the area along the coast in south-west Wales from Wooltack Point to St Govan's Head, including Milford Haven and the tidal waters of the East and West Cleddau river;
• Loch Sunart, Highland;
• West Loch Tarbert, Argyll;
• Dornoch Firth, Highland;
• Lynn of Lorne, Loch Creran and Loch Etive, Strathclyde;
• Menai Strait.

Guernsey, Herm and the Isle of Man are all recognised as Bonamia ostreae free areas. The whole coastline of Northern Ireland is recognised as free from Bonamia ostreae apart from Lough Foyle and Strangford Lough. Jersey is no longer recognised as free from Bonamia ostreae.

The whole coastline of Great Britain is recognised as free from OsHV-1 μvar except for the following areas:

• River Roach, River Crouch, Blackwater Estuary and River Colne in Essex;
• the north Kent coast;
• Poole Harbour in Dorset;
• the River Teign in Devon.

Guernsey is also recognised as free from OsHV-1 μvar. In the territory of Northern Ireland, Belfast Lough is the only area approved as free from OsHV-1 μvar.

Movements of shellfish species susceptible to infection by Marteilia refringens, Bonamia ostreae and OsHV-1 μvar, into the Great Britain health zone, must originate from another zone or country recognised as free of that disease. Movements are allowed from disease free areas to non-approved areas, as well as those for direct human consumption without re-immersion in any other sea water areas.