Scottish Shellfish Farm Production Survey 2013

This report is based on the returns of an annual survey questionnaire sent to all active authorised shellfish farming businesses in Scotland.

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In accordance with Council Directive 2006/88/ EC, a risk based surveillance programme targeting 91 shellfish site inspections was undertaken during 2013. 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 seven sites, including 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 place in Loch Sunart and in West Loch Tarbet during 2013. 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 continued to protect the health of both wild and farmed native oyster stocks for the remainder of Scotland's waters.

Most of the reported mortalities were attributed to: predation from wild ducks, starfish and oyster catchers; adverse weather conditions including storms and frost; damage due to grading and handling and from natural causes. Reports of high, unexplained shellfish mortalities generated three shellfish diagnostic cases during 2013, at sites holding mussels. Results of diagnostic investigations showed no association with 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 2013 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 of pests and pathogens, 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 Ostreid Herpes Virus 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 territorial waters of Great Britain (except Whitstable Bay (Kent), Blackwater estuary (Essex), Poole Harbour (Dorset)), Larne Lough in Northern Ireland and Guernsey. 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.


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