Scottish Shellfish Farm Production Survey 2015

// Health Influences on the Industry

In accordance with Council Directive 2006/88/EC, a risk based surveillance programme targeting 92 shellfish site inspections was undertaken during 2015. On these visits, facilities, stock health, bio-security measures plans, movement records and details required for authorisation were checked. In addition, native oysters were sampled from nine farm sites, and three wild beds, for the notifiable diseases bonamiasis (causative agent, protozoan parasite Bonamia ostreae) and marteiliasis (causative agent, protozoan parasite Marteilia refringens). Results were negative. Native oyster is a species known to be susceptible to these shellfish diseases. Movement restrictions placed due to confirmation of the presence of Bonamia ostrea, remained in force in Loch Sunart and in West Loch Tarbert, Argyll during 2015. These movement restrictions covering both sea lochs prevent the relaying of native oyster from them ( see Appendix 2 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.

Most of the reported mortalities during 2015 were attributed to: predation from wild ducks, starfish, crabs and oyster catchers; 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 four shellfish diagnostic cases during 2015, at sites holding Pacific and native 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 2015 there was a continued demand for imported mussel seed into Scotland to supplement the vagaries in natural settlement. 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 March 2010 Commission Regulation No. 175/2010 was introduced to implement Council Directive 2006/88/EC as regards measures to control increased mortality in Pacific oysters, in connection with the detection of OsHV-1 µvar.

Following completion of a targeted surveillance programme, the UK has been granted disease free status for OsHV-1 μvar (Decision 2014/12/EU). This includes the territory of Great Britain except the River Roach, River Crouch Blackwater Estuary and River Colne in Essex, the north Kent Coast, Poole Harbour in Dorset and the River Teign in Devon. In addition, Guernsey and the territory of Northern Ireland (except Dundrum Bay, Killough Bay, Lough Foyle, Carlingford Lough and Strangford Lough) have also been granted disease free status for OsHV-1 μvar.

In 2015 six compartments in Ireland were also recognised as free from OsHV-1 μvar: compartment 1 - Sheephaven Bay, compartment 3 - Killala, Broadhaven and Blacksod Bays, compartment 4 - Streamstown Bay, compartment 5 - Bertraghboy and Galway Bays, compartment 6 - Poulnasharry Bay and compartment A - Tralee Bay Hatchery.

Movements of Pacific oysters into an area recognised as free from OsHV-1 μvar must originate from another disease free area. Movements are still allowed from disease free areas to non-approved areas.

http://www.gov.scot/Topics/marine/Fish-Shellfish/aquaculture/diseases/notifiableDisease/oshvdec