Scalpay, Isle of Skye

Transcription

1 Scalpay, Isle of Skye REPORT WRITTEN BY AUTODEPOMOD MODELLIN G REPORT V1 ENVIRONMENTA L ANALYST) ENVIRONMENTAL MAN AGER) Registered in Scotland No Registered Office, 1st Floor, Admiralty Park, Admiralty Road, Rosyth, FIFE, KY11 2YW Marine Harvest ( Scotland) Limited, Stob Ban House, Glen Nevis Business Park, Fort William, PH33 6RX Marine Harvest ( Scotland) Limited, Stob Ban House, Glen Nevis Business Park, Fort William, PH33 6RX marineharvest. com

2 CONTENTS Page EXECUTIVE SUMMARY 1 1 INTRODUCTION 2 2 MODEL INPUT DETAILS HYDROGRAPHIC DATA SITE DETAILS RUN DETAILS 6 3 MODELLING RESULTS BIOMASS RESULTS TRANSECT AND SAMPLING STATIONS IN-FEED TREATMENTS SLICE BATH MODEL RESULTS 11 4 RESULTS AND CONCLUSIONS 12 REFERENCES 14 1

3 List of Figures Figure 1 Location of the Salmon Farm... 2 Figure 2 Site current direction frequency from the surface current meter... 4 Figure 3 bathymetry and cage layout... 6 Figure 5 Location of the selected and spare transects... 8 Figure 6 Cross-sections of both the selected and spare transects respectively... 9 Figure 7 EmBZ concentrations for run 1 (118 days) List of Tables Table 1 Summary of Results... 1 Table 2 A summary of the mean and residual currents recorded at the site... 4 Table 3 Project Information... 5 Table 5 Selected and Spare Transect Starting Points... 8 Table 6a&b The details of the three selected and spare survey stations respectively... 9 Table 7 Modelling Results Summarised

4 EXECUTIVE SUMMARY This report has been prepared by Marine Harvest ( Scotland) Ltd. to meet the requirements of the Scottish Environment Protection Agency ( SEPA) for the purpose of assessing an application to install equipment and consequent biomass, and for consent to use sufficient sealice treatments in a marine salmon farm, via AutoDepomod and dispersion modelling. The report describes biomass, in-feed and bath treatment modelling results for the Scalpay site, a summary of which is provided in Table 1 below. The report held centrally, and previously accredited, by SEPA (AMMR11v02) details modelling methods used. Table 1 Summary of Results Site Name: Site location: SITE DETAILS Scalpay Isle of Scalpay, Isle of Skye Peak biomass ( T): 2,500 CAGE DETAILS Number of cages: 12 Cage dimensions: 120m Circumference Working Depth ( m): 12 Cage group configuration: Surface Currents Middle Currents Seabed Currents HYDROGRAPHIC SUMMARY 2(2x3), 75x70m matrix Average Speed (m/s) Residual Direction 0.040m/s at 323 G Wind-Influence Average Speed (m/s) Slight 0.060m/s Residual Direction 0.034m/s at 310 G Average Speed (m/s) 0.053m/s Residual Direction 0.018m/s at 86 G BENTHIC MODELLING Max fish biomass proposed (T) 2,500t Max Average Stocking Density ( kg/m³) Distance to the 30ITI contour (m) Direction of transect ( T) IN-FEED TREATMENTS Recommended consent mass EmBZ (g) 4,375 Equivalent Fish Biomass (T) Maximum Treatment Amount EmBZ ( g) 875 BATH TREATMENTS Recommended consent mass in 3hrs Azamethiphos 269.3g cage/treatment, 1.2 treatments/ day Recommended consent mass in 24 hrs Azamethiphos 687.7g cage/treatment, 3 treatments/ day Recommended consent mass in 3 hrs Cypermethrin Recommended consent mass in 3 hrs Deltamethrin 48.7g cages/treatment, 4.3 treatments/ day 18.3g cages/treatment, 4 treatments/ day 1

5 1 INTRODUCTION This report has been prepared by Marine Harvest to meet the requirements of the Scottish Environment Protection Agency ( SEPA) for the purpose of assessing an application to install equipment and consequent biomass, and for consent to use sufficient sealice treatments, via AutoDepomod and dispersion modelling. The report describes modelling results for a new site off the neighbouring island of Scalpay (Figure 1) to determine EQScompliant biomass and sea-lice treatment levels for the proposed equipment. Report number AMMR11v02 which is held centrally, and has been previously accredited, by SEPA, provides details of the generic modelling methods used. Figure 1 Location of the Salmon Farm North Isle of Scalpay 2

6 2 MODEL INPUT DETAILS 2.1 HYDROGRAPHIC DATA The site data was collected by Marine Harvest for the purpose of assessing a consent application with the AutoDepomod software. Methods of the data collection and analysis followed current SEPA guidelines (SEPA, 2005); the data used were of 15 days duration and were analysed using both the appropriate SEPA hydrographic excel template for 20 minute data and the hg-analysis spreadsheet, also provided by SEPA. The Admiralty Hydrographic Office tide prediction software Total Tide was used to determine the start dates of spring and neap tides and to determine the times of high water and mean tidal height for the area (see Table 3). Following SEPA guidelines the start points in the current meter record used for modelling are those closest to midday on the day of the intermediate spring tides and the intermediate neap tides. In the current meter data used, after hourly averaging, the times of intermediate HW spring and HW neap corresponded to records 94 and 289 respectively. Prior to commencement of modelling the current data required correction to Grid North and was thus corrected by 4.029W. The hourly averaged current data for the surface, middle and bottom bins were then saved as space delimited files, as detailed in AMMR11v02 and following the default AutoDepomod file structure. Using the hg-analysis spreadsheet the mean speed and the residual current speed and direction were established for each of the three current meter depths. The mean and residual currents, and the histogram frequency peaks are summarised in Table 2 below. The data showed a predominant current in a north-westerly direction at near-surface and mid depths. Whereas slower data recorded near-bed showed a north-easterly direction. A slight correlation was found between the surface current speeds and the wind speeds (Figure 2); however a tidal pattern can still be seen. The mean wind speed over this period was 4.0m/s. 3

7 Figure 2 Site current direction frequency from the surface current meter bin24determine tidal ellipse major axis Site: Scalpay_ subs_ 32.7m_ FrequencyOf Readings In Bin Percentage Of Current SpeedsIn Bin (%) Navigation 100% SURFACE Mean Speed m/s Residual Speed m/s Residual Parallel m/s Residual Normal m/s Tidal Amplitude Parallel m/ s Tidal Amplitude Normal m/ s Frequency Peak 330 MIDDLE Mean Speed m/ s Residual Speed m/ s Frequency Peak 320 BOTTOMMean Speed m/s Residual Speed m/s 0. 4

8 2.2 SITE DETAILS The proposed site is situated near the south-eastern shore of the Isle of Scalpay ( Figure 1). Marine Harvest proposes to install equipment and operate a maximum biomass of 2,500t at the new site and so the AutoDepomod and the Bath Treatment models have been run to determine EQS-compliant biomass and medicinal consents for this new equipment. Details of the site are provided in Table 3. The receiving water is defined as open water. Table 3 Project Information SITE DETAILS Site Name: Scalpay Site location: Isle of Scalpay, near the Isle of Skye Peak biomass (T): 2,500 Proposed feed load (T/yr): 6,387.5 Proposed treatment use: CAGE DETAILS Azamethiphos, Cypermethrin, Deltamethrin & Emamectin Benzoate Group location: E, N; E, N Number of cages: 12 Cage dimensions: 120m circumference Working Depth ( m): 12 Cage group configuration: 2(2x3) Cage group orientation ( G): 0 Cage group distance to shore (km): 0.60 Water depth at site (m): 35 HYDROGRAPHIC DATA Current meter position: E, N Depth at deployment position ( m): 37.8 Surface bin centre height above bed (m): 32.7 Middle bin centre height above bed (m): 25.7 Bottom bin centre height above bed (m): 2.7 Duration of record: 10/11/13 13:55 to 25/11/13 13:55 Current meter averaging interval: 20 min ADDITIONAL DATA Magnetic correction to grid North: Predicted Spring Tide 11/11/2016 Predicted Neap Tide 18/11/2016 Predicted Spring Tide 26/11/2016 Mean Tidal Level at Site (m): 3.15 Closest Standard Port Broadford Bay Date of Intermediate- Spring Tides: 14/11/2016 Date of Intermediate- Neap Tides: 22/11/2016 5

9 2.3 RUN DETAILS A new project was created in AutoDepomod and named Scalpay16 vf1. The site and cage details provided in Table 3 were entered into the appropriate files and all other data were set to default. The resulting site bathymetry and cage layout is shown in Figure 3. Modelling of both the biomass and chemotherapeutants was undertaken following the methods outlined in the Methods Report AMMR11v02 which is held centrally by SEPA. Details of the modelling results have been provided in the next section according to SEPA requirements. Figure 3 bathymetry and cage layout Two types of treatment are used to control sea lice infestation in marine salmon farms and these require different modelling approaches. The in-feed treatment Slice (active ingredient Emamectin Benzoate) requires deposition modelling using AutoDepomod to predict the chemical accumulation on the seabed beneath the fish cages associated with fish faeces and uneaten treated feed. The bath treatments Salmosan ( chemical name Azamethiphos), Excis chemical name Cypermethrin) and Alphamax ( Deltamethrin), where the salmon are immersed in a diluted solution of the treatment chemical require dispersion modelling to predict the concentration in the water column after release. Results from both AutoDepomod and the Bath model have been provided in the next section. 6

10 3 MODELLING RESULTS 3.1 BIOMASS RESULTS AutoDepomod was run initially with the company s preferred stocking density of kg/ m3, and proposed cage layout, using the model s auto-distribute biomass function. The model did not require to iterate to an EQS-complaint solution as a pass was achieved at this stocking density and pen volume for the resultant maximum allowable biomass of 2,500 tonnes. At this biomass the model predicts the 80% solids area to be 101,519m2 while the flux in this area is expected to be 1,516g/m2/year. The proposed layout and tonnage results in a benthic cage area of 40,726m2 with a minimum ITI of 1 within the area. The flux in the benthic cage group area is predicted to exceed the trigger value (10,000g/m2/year) at 14,438g/m2/year. The benthic sampling area (ITI = 30) is expected to be 148,354.4m2 while the flux inside this area will be 191.8g/m2/year. The plotted AutoDepomod output for the passing Int-Spring run 2 is shown in Figure 4. A summary with all of this information can be found in Scalpay16 vf1_marine_sum_v3.xls and in Table 7 of this report. Figure 4 Benthic impact for run 2, Int-Spring current data The mass of solids released in run 2 is estimated to be 1,020,815kg with 92% (937,154kg) predicted to remain within the 1km2 modelling grid, thus 8% ( 83,661kg) of the input load is predicted to be transported from the model grid as a result of resuspension. Current data recorded at the site results in a vector average residual of 0.040m/s at 323 G at the surface, 0.034m/s at 310 G at the middle, and 0.018m/s at 86 G. Figure 4 shows the dispersal of waste material in a northerly direction. 7

11 3.1.1 TRANSECT AND SAMPLING STATIONS Two transect profiles were created ( Figure 4) as part of SEPA s requirements to determine site-specific sampling locations. The selected and spare transect information have been saved to the Scalpay 16vF1- BcnstFI- S-2_000.xls file located in the mapping folder. Details of both transect starting points are provided in Table 4 below. Figure 4 Location of the selected and spare transects Transect X1 Y1 X2 Y2 Bearing Length Depth T T Table 4 Selected and Spare Transect Starting Points 8

12 Table 5 describe the location and details of the three selected and spare survey stations. Figure 5 shows the cross-sections of the selected and spare transects, and the relevant survey stations. SELECTED EQS - 10m 1st Station) S1 EQS 2nd Station) S2 EQS + 10m 3rd Station) S3 SPARE EQS - 10m 1st Station) S1 EQS 2nd Station) S2 EQS + 10m 3rd Station) S3 NGR Easting NGR Easting NGR Northing NGR Northing Distance ( m) Distance ( m) CD depth (m) CD depth (m) Modelled ITI Modelled ITI Table 5a&b The details of the three selected and spare survey stations respectively Figure 5 Cross- sections of both the selected and spare transects respectively 9

13 3.2 IN-FEED TREATMENTS SLICE The SLICE aspect of AutoDepomod was run initially for a Total Allowable Quantity sufficient to treat 5 times the proposed peak biomass (4,375g & 12,500 tonnes respectively). Marine Harvest have followed SEPA s guidance and used a feedload of T derived from the default feed figure automatically generated in the Biomass Section of AutoDepomod. The model did not require to iterate to an EQS-complaint solution as a pass was achieved at this quantity and biomass. The predicted area inside the g/kg contour ( 208,797m2) was smaller than the predicted far field AZE area ( 213,248m2). The mean concentration of Slice in the near field AZE exceeds the EQS trigger value of 7.63g/kg by 289.7g/kg and thus enhanced monitoring will be required at the site if Slice is used. The plotted AutoDepomod output for this run is shown in Figure 6. A further run for 223 days duration was performed to obtain a site residual curve for this biomass. Figure 6 EmBZ concentrations for run 1 (118 days) The mass of EmBZ remaining on the bed at the end of run 1 was 2,906g. For Slice, in the absence of resuspension, 74% or 3,237.5g of the input EmBZ load would remain on the seabed after 118 days. This indicates that a low percentage of the original input load is lost through resuspension ( 7.6%). The mass of EmBZ lost from the grid ( 331.5g) represents an equivalent area of 3.6km2 if it assumed to distribute evenly at the far field EQS concentration of 0.763g/kg sediment. 10

14 3.3 BATH MODEL RESULTS Cage details are given in section 2. The cage treatment depth used for the bath treatments was 2m. Using the results from the analysis of the surface current meter data in the short term bath treatment model EQS compliance for both Deltamethrin and Cypermethrin at this cage depth was predicted. EQS compliance for Azamethiphos was predicted at a cage depth of 2m. Cypermethrin & Deltamethrin Results: Cage Treatment Depth = 2m Permissible Quantity of Cypermethrin = 48.7g; 4.3 cages/3 hours Permissible Quantity of Deltamethrin = 18.3g; 4 cages/3 hours Azamethiphos Results: Cage treatment depth = 2m Permissible Quantity of Azamethiphos = 269.3g; 1.2 cages/3 hours Permissible Quantity of Azamethiphos = 687.7g; 3.0 cages/24 hours The permissible quantities means that full treatment of the 12 pens at the site, would take approximately 3 days to complete. The bath treatment model files are saved in the folder Scalpay 16vF1\Bath 11

15 4 RESULTS AND CONCLUSIONS It is recommended that the biomass and treatment amounts are consented at this site as given below in. The results of the modelling performed at this site are given in the file : Scalpay16vF1_marine_sum_v3.xls in the Scalpay16vF1 folder. BENTHIC MODELLING: Max fish biomass proposed ( T) 2,500 Cage depth (m) 12 Max Average Stocking Density (kg/m³) Maximum number of cages 12 loss of solids from model grid (%) 8 Cage area equivalent ( m²) 40,726 Flux in the cage area (g/m²/y) 14,438 ITI in the cage area 1 Flux under cages exceeds the trigger value 80% solids area (m²) 101,519 Flux in the 80% solids area (g/m²/y) 1,516 ITI in the 80% solids area 10.2 Benthic sampling area (m²) 148,354.4 Flux in the benthic sampling area (g/m²/y) ITI in benthic sampling area 30 SITE SPECIFIC SAMPLING: Transect start coordinates , Direction ( T) CD Depth (m) 35.5 Distance to the 30ITI contour (m) SPARE TRANSECT INFORMATION Transect start coordinates , Direction ( T) CD Depth (m) 36.9 Distance to the 30ITI contour (m) 67.5 IN-FEED TREATMENTS Peak fish biomass at site (T) 2,500 Near Field AZE (m²) 68,887 Far Field AZE (m²) 213,248 Recommended consent mass EmBZ ( g) 4,375 Equivalent Fish Biomass ( T) 12,500 Maximum Treatment Amount EmBZ ( g) 875 Area of Impact at Far Field EQS (m2) 208,797 loss of EmBZ from model grid (%

16 BATH TREATMENTS Recommended consent mass in 3hrs Azamethiphos Recommended consent mass in 24 hrs Azamethiphos Recommended consent mass in 3 hrs Cypermethrin Recommended consent mass in 3 hrs Deltamethrin 269.3g cage/treatment, 1.2 treatments/ day 687.7g cage/treatment, 3 treatments/ day 48.7g cages/treatment, 4.3 treatments/ day 18.3g cages/treatment, 4 treatments/day Table 6 Modelling Results Summarised 13

17 REFERENCES SEPA Regulation and monitoring of marine cage fish farming in Scotland - a procedures manual: Annex G Models for assessing the use of medicines in bath treatments (January 2007). SEPA, Regulation and monitoring of marine cage fish farming in Scotland - a procedures manual: Annex H - Methods for Modelling In-Feed Anti-Parasitics and Benthic Effects (June 2005) SEPA, Regulation and monitoring of marine cage fish farming in Scotland - a procedures manual: Attachment VIII Hydrographic data requirements for applications to discharge from Marine Cage Fish Farm (May 2005). UKHO, Admiralty Tide Tables; volume 1 UK and Ireland. United Kingdom Hydrographic Office, Taunton. 14