Scottish Sanitary Survey Programme Sanitary Survey Report Production Area: Hamnavoe SI 348 January 2012 Report Distribution – Hamnavoe Date Name Agency Linda Galbraith Scottish Government Mike Watson Scottish Government Morag MacKenzie SEPA Douglas Sinclair SEPA Fiona Garner Scottish Water Alex Adrian Crown Estate Dawn Manson Shetland Island Council Sean Williamson NAFC Scalloway Christopher Harvester Thomason Chris Webb Northern Isles Salmon Hamnavoe Sanitary Survey Report V1.0 10/05/2011 i Table of Contents I. Executive Summary .................................................................................. 1 II. Sampling Plan ........................................................................................... 3 III. Report ................................................................................................... 4 1. General Description .................................................................................. 4 2. Fishery ...................................................................................................... 5 3. Human Population .................................................................................... 6 4. Sewage Discharges .................................................................................. 8 5. Geology and Soils ................................................................................... 11 6. Land Cover ............................................................................................. 12 7. Farm Animals .......................................................................................... 13 8. Wildlife .................................................................................................... 15 9. Meteorological data ................................................................................ 18 9.1 Rainfall............................................................................................. 18 9.2 Wind ................................................................................................ 19 10. Current and historical classification status .......................................... 22 11. Historical E. coli data ........................................................................... 23 11.1 Validation of historical data .............................................................. 23 11.2 Summary of microbiological results ................................................. 24 11.3 Overall geographical pattern of results ............................................ 24 11.4 Overall temporal pattern of results ................................................... 25 11.5 Seasonal pattern of results .............................................................. 26 11.6 Analysis of results against environmental factors ........................... 28 11.6 Evaluation of results over 230 E. coli MPN/100g ............................. 31 11.7 Summary and conclusions ............................................................... 32 11.8 Sampling frequency ......................................................................... 32 12. Designated Shellfish Growing Waters Data ........................................ 33 13. River Flow ........................................................................................... 34 14. Bathymetry and Hydrodynamics ......................................................... 36 14.1 Tidal Curve and Description ............................................................ 36 14.2 Currents ........................................................................................... 37 14.3 Conclusions ..................................................................................... 39 15. Shoreline Survey Overview ................................................................. 41 16. Overall Assessment ............................................................................ 43 17. Recommendations .............................................................................. 46 18. References .......................................................................................... 48 19. List of Figures and Tables ................................................................... 49 Appendices 1. Geology and Soils Information 2. General Information on Wildlife Impacts 3. Tables of Typical Faecal Bacteria Concentrations 4. Statistical Data 5. Hydrographic Methods 6. Shoreline Survey Report © Crown Copyright 2012. Food Standards Agency Scotland and Cefas. All rights reserved. Hamnavoe Sanitary Survey Report V1.0 10/05/2011 ii I. Executive Summary A sanitary survey at Hamnavoe has been undertaken as the area was first classified after 2006, when the requirement to conduct sanitary surveys under Regulation (EC) No. 854/2004 came into force. Hamnavoe is located at the southern end of the island of Yell in the Northern Shetland Islands. The area surrounding the fishery is sparsely populated, the only settlements being the small hamlets of Copister on the western shoreline and Hamnavoe, Houlland, Burravoe and Upper Neapback on the eastern shoreline. The fishery at Hamnavoe is for mussels and uses a system supplied by Smart Farm AS consisting of 4 sets of 7 polyethylene pipes with rope collectors dropping to 2.2 m. Harvesting may be undertaken at any time of year. The current nominal Representative Monitoring Point (RMP) lies 40 m west of the mussel lines. The principal sources of faecal contamination to the fishery are from the Hamnavoe septic tank and potentially from the smaller pipes which lie nearest to the fishery. Contaminants from these discharges would need to pass the mussel farm to exit the loch and as such impacts from these are most likely to affect the northern end of the mussel farm. Historical monitoring showed that the underlying level of contamination appeared to be stable across the period of this assessment but, within individual years, there was a tendency for a peak in E. coli contamination in the latter half of the year. Further analysis showed higher levels in summer and autumn, with results in summer being significantly higher than in spring and winter. There was some correlation seen with water temperature and with rainfall prior to sampling. The general level of contamination of the mussels is low with intermittent, but ongoing, results greater than 230 E. coli MPN/100 g. During the shoreline survey of the area, water samples taken from the watercourse discharging to the area indicated that the main concentration of contamination would tend to impact on the north-east end of the mussel lines. Based on the animals observed during the shoreline survey, and the reported numbers for the agricultural parish, it is likely that a significant proportion of any faecal contamination impacting on the fishery is from diffuse, livestock sources. Direct deposition of droppings at the shoreline and in and around watercourses is likely to pose the greatest threat to water quality at the fishery. Direct runoff from the steep hillside to the west of the fishery may carry livestock faeces to the waters immediately west of the shellfish farm. Wildlife is likely to be present in modest numbers and will contribute to background levels of contamination at the fishery. Overall the area receives some input of human sewage and agricultural diffuse pollution. Hamnavoe Sanitary Survey Report V1.0 10/05/2011 1 Recommendations The recommended production area boundaries were changed slightly from the existing boundary. This was done to exclude the area nearest the head of the voe because contaminants there are likely to be more concentrated than at the fishery. The southern boundary locations were adjusted slightly to bring them in line with MHWS. The recommended production area boundaries are: the area bounded by lines drawn between HU 4900 7974 to HU 4900 7920 and HU 4835 8000 to HU 4889 8000, extending to MHWS. It is recommended that the RMP be relocated to HU 4864 7950, which lies on the west side toward the southern end of the mussel farm. Assessment of monitoring results from the last three years did not indicate that the area was suitable for reduced sampling frequency. Therefore, it is recommended that monthly monitoring be maintained. As most of the potential sources of contamination to the head of the voe are likely to be found near the surface, it is recommended that the sampling depth be 1m. A 40 metre sampling tolerance is recommended to allow scope for locating a sampling rope or bag at a suitable place on the mussel farm and to allow for movement of the lines. Hamnavoe Sanitary Survey Report V1.0 10/05/2011 2 II. Sampling Plan PRODUCTION Hamnavoe AREA SITE NAME Copister SIN SI 348 736 08 SPECIES Common Mussels TYPE OF FISHERY Aquaculture, longline NGR OF RMP HU 4864 7950 EAST 448640 NORTH 1179500 TOLERANCE (M) 40 DEPTH (M) 1 METHOD OF Hand SAMPLING FREQUENCY OF Monthly SAMPLING LOCAL Shetland Island Council AUTHORITY AUTHORISED SAMPLER(S) LOCAL AUTHORITY LIAISON OFFICER Hamnavoe Sanitary Survey Report V1.0 10/05/2011 3 III. Report 1. General Description A sanitary survey at Hamnavoe has been undertaken as the area was first classified after 2006, when the requirement to conduct sanitary surveys under Regulation (EC) No. 854/2004 came into force. Hamnavoe is located at the southern end of the island of Yell in the Northern Shetland Islands (see Figure 1.1). The voe is approximately 1.5 km in length and ranges in width from 300m at its head near Salt Ness to 700m at its mouth. The voe is oriented toward the southeast. © Crown Copyright and Database 2012.