BIOMASS AND CHEMOTHERAPEUTANT
TECHNICAL MODELLING REPORT
BALTA ISLE
CAR/ L/ 1003872
Author:
Report date: 17 May 2017 Cooke Aquaculture
Scotland
Crowness Rd,
Hatston Industrial Estate,
Kirkwall,
Orkney, KW15 1RG
T: + 44 ( 0) 1856 876101
www. cookeaqua. com Balta Isle Technical Modelling Report May 17, 2017
Table of Contents
1. Summary...... 2
2. Introduction...... 3
3. Input data...... 4
3. 1 Site data...... 4
3. 2 Hydrographic data...... 5
3. 3 Bathymetric data...... 6
3. 4 Bath modelling...... 7
4. Results...... 8
4. 1 Biomass...... 8
4. 1. 1 Transects and sampling stations...... 9
4. 1. 2 Fate Assessment of Exported Material...... 12
4. 2 In -feed treatments...... 15
4. 2. 1 Slice — Emamectin Benzoate...... 15
4. 3 Bath treatments...... 19
4. 3. 1 Salmosan Vet — Azamethiphos...... 19
4. 3. 2 Excis - Cypermethrin...... 20
4. 3. 3 Alphamax - Deltamethrin...... 20
4. 3. 4 Alternative bath model — "Loch" scenario...... 20
5. Discussion...... 21
6. References...... 23
7. Appendices...... 24
7. 1 Appendix 1 - Changeover to Salmosan Vet...... 24
7. 2 Appendix 2 — Data comparison of three Balta Isle hydrographic data sets ( 15 days)... 26
7. 3 Appendix 3 — Model outputs generated using the three Balta Isle hydrographic data
sets...... 27
Cooke Aquaculture Scotland Page 1 1 27 Balta Isle Technical Modelling Report May 17, 2017
1. Summary
Cooke Aquaculture Scotland Ltd. ( CAS) has undertaken biomass and chemotherapeutant modelling work for the marine cage fish farm site, Balta Isle in Shetland. The site is located off the west coast of the island of Balta in Balta Sound, a water body which runs between the islands of Unst and Balta. The proposed new set up at the site is for two groups of 10x100m circular cages arranged in 5x2 cage configurations. The site was modelled to determine the maximum biomass and the recommended consent limits of in -feed treatments and bath treatments in regards to the new infrastructure and the biomass being proposed. Site specific benthic monitoring transects were defined with a primary sampling transect originating from the north east cage on the northern cage group on a bearing of 21. 7° G. The recommended consent limits achieved are detailed in Table 1.
Table 1 Summary of the Recommended Consent Limits for the Balta Isle site.
Maximum Biomass 2, 184. 8t Stocking density 19. 6kg/ m3
In - Feed Treatments
DCIILUd LC TAQ MTQ
Mass ( g) 3, 823. 4 764. 7
Equivalent Treatable 10, 924 2, 184. 8 Biomass ( t)
Bath treatments
Azamethiphos Cypermethrin Deltamethrin
3hr 24hr 3hr 3hr
Mass ( g) 130. 58 109 23. 64 8. 86
Equivalent Treatable 1, 306 1, 090 4, 727 4, 432 Volume ( m3)
Cooke Aquaculture Scotland Page 2 1 27 Balta Isle Technical Modelling Report May 17, 2017
2. Introduction
The proposed new cage setup at the Balta Isle site is to consist of 20x100m circumference cages. The cages will be split into two groups of ten cages arranged in 5x2 configurations.
The cage groups will run parallel to the Balta coastline with the north site orientated to 319° and the south site orientated to 50°. The cages will be housed in 60m square grids with a net depth of 7m. The site centre of the north cage group is 60o45. 180' N 00°47. 895' W ( HP 65603 08370) and the site centre for the south cage group is 60°44. 955' N 00° 47. 966' W ( HP 65546 07951). Figure 1 illustrates the location of the Balta Isle site.
The proposed new set up at the Balta Isle fish farm has been modelled to determine the maximum permissible biomass at the site and to produce a monitoring protocol recommendation for submission to SEPA. In addition, the quantities of the in -feed treatment Slice and the bath treatments Salmosan Vet, Excis and Alphamax have been determined ensuring they are compliant with the required standards set by SEPA under The Water Environment ( Controlled Activities) ( Scotland) Regulations 2011 ( CAR).
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Cooke Aquaculture Scotland Page 3 1 27 g1 Balta Isle Technical Modelling Report May 17, 2017
3. Input data
3. 1 Site data
AutoDEPOMOD version 2. 0. 52 is used to simulate the release and deposition of waste feed and faecal material on the seabed from which the benthic impact is predicted. For in -feed treatments the area and concentration of chemical deposition are derived via simulation of the chemical load associated with this material. Residual discharge concentrations are calculated using aqueous discharge models for bath treatments ( BathAuto version 5. 1).
The distance to shore parameter is taken as the distance from a site centre position located between the two cage groups 60045. 065' N 00047. 746W ( HP 65742 08159) to the nearest shoreline on Balta to the east. The average water depth is determined from the AutoDEPOMOD bathymetry grid file utilising the Surfer volume calculations. Background information on the techniques employed are detailed in a separate methods report Biomass and Chemotherapeutant Modelling Methods Report' which can be found on the USB flash drive.
Site specific data for the Balta Isle site required by AutoDEPOMOD are presented in Table 2.
Table 2 Site Input Data
Site name Balta Isle
Consent Number CAR/ L/ 1003872 Company Cooke Aquaculture Scotland Receiving water Balta Sound Site NGR 465742 1208159
Current meter NGR 465557 1208195
Distance to shore ( km) 0. 163
Average water depth ( m) 10. 3
Number of cages 20
Shape of cages Circular
Circumference of cages ( m) 100 ( Radius— 15. 92m) Cage group configuration 2 groups - 5x2 Grid size ( ml) 60
Cage group orientation (* Grid) N group - 319° / S group - 50° Working net depth ( m) 7 Treatment net depth ( m) 1. 64
Cooke Aquaculture Scotland Page 4 1 27 Balta Isle Technical Modelling Report May 17, 2017
3. 2 Hydrographic data
A hydrographic survey at the Balta Isle site was carried out in March 2016. The data and report was accepted by SEPA as being suitable for modelling purposes. A 15 day subset of data was selected running from 2 to 17 March 2016 using data from three specified depths that represented near surface, cage bottom and near seabed layers. Direction data are supplied pre -corrected to Grid North. Intermediate spring and neap tides were identified from tidal heights for the port of Baltasound Pier. Raw current velocity data was formatted for use in AutoDEPOMOD using the SEPA template ' temp- 20min- HGv3. xls' ( files created
Balta Isle- HG. xls', ' Balta Isle- NS- b. dat', ' Balta Isle- NS- m. dat', ' Balta Isle- NS- s. dat').
The hydrographic input data is shown in Table 3 below:
Table 3 Hydrographic Data Input
Depth of current meter ( m) 14. 25
Height of surface cell from the seabed ( m) 8. 7
Height of middle cell from the seabed ( m) 6. 7
Height of bottom cell from the seabed ( m) 3. 7 Date Spring Tide commence 07/ 03/ 2016 Data record number) 121) Date Neap Tide commence 14/ 03/ 2016 Data record number) 289)
Current Speed unit m/ s
Mean Sea Level ( m)* 1. 42
Compass variation O. Ow Source:* Admiralty TotalTide Version 17, 0, 0, 5 - Nearest port: Baltasound Pier
Two additional hydrographic data sets ( North and South) were collected at the Balta Isle site, with a meter deployed near the north cage group ( November/ December 2016) and a meter deployed near the south cage group ( November 2016). The data set used in this modelling report collected in March 2016 ( Mid) was deemed most suitable and representative of the flow conditions around the site due to its location between the two cage groups. A comparison of the three hydrographic data sets was undertaken with the main parameters outlined in Appendix 2. The outputs generated by AutoDEPOMOD using the three different data sets within the model have been reported in Appendix 3.
Cooke Aquaculture Scotland Page 5 1 27 1208600
1208400
1208200
1208000
1207800
465000 465200 465400 465600 465800 466000
Eastings Balta Isle Technical Modelling Report May 17, 2017
3. 4 Bath modelling
For the long term bath treatment model the " strait" scenario was considered as the most appropriate to the site location. For the input parameters, the strait was defined by the following boundaries; at the north mouth between The Rett, Unst ( HP 65506 09191) and the north end of Balta ( HP 65858 09172) and at the south mouth, a mid point on the eastern coast of Huney ( HP 65076 06320) and the south end of Balta ( HP 65780 06902). At the north end of the strait Balta Sound does continue west towards Baltasound Harbour, however this inlet was not included in the strait calculations with the western boundary of the strait defined between Swinna Ness, Unst ( HP 65327 08959) and Swarta Skerry, Unst ( HP 64824 07924). The length of the strait was measured at 2. 72km with a low water area of 2. 24k M2, therefore the average width of the strait was calculated as 0. 82km. The distance to shore parameter is measured as the distance from the site centre between the two cage groups to the shoreline to the east, while the distance to head parameter is measured from the site centre to the boundary at the north mouth of the strait. The average water depth is determined from the AutoDEPOMOD bathymetry grid file utilising Surfer volume calculations.
Input data used in the BathAuto_ v5 excel workbook are shown in Table 4 below:
Table 4 Bath model Data Input Type of water body Strait Distance to head ( km) 1. 22
Distance to shore ( km) 0. 16
Width of Strait ( km) 0. 82
Average water depth ( m) 10. 31
Number of cages 20
Diameter of cage ( m) 31. 8
Net depth ( m) 7 Stocking density (kg/ m3) 19. 6 Surface mean current speed ( m/ s) 0. 064
Surface Residual Parallel component ( m/ s) 0. 026
Surface Residual Normal component ( m/ s) 0. 035
Surface Tidal Amplitude Parallel Component ( m/ s) 0. 079
Surface Tidal Amplitude Normal Component ( m/ s) 0. 041
The bath model was run again using the " loch" scenario to include the Baltasound Harbour area to the west of the strait. Sea loch parameters outlined in Marine Scotland Science
Locational Guidelines for the Authorisation of Marine Fish Farms in Scottish Waters' ( March 2017) for Balta Sound were used in the model with the length of the loch given as 2. 9km and the area of the loch 3. 7kM2. The distance to head was measured from the site centre to the head of Balta Sound to the west towards Baltasound Harbour ( 3. 6km).
Both the strait and loch scenario BathAuto_ v5 excel workbooks can be found on the USB flash drive.
Cooke Aquaculture Scotland Page 7 1 27
Balta Isle Technical Modelling Report May 17, 2017
4. 1. 1 Transects and sampling stations A primary transect has been proposed on the northern cage group originating from the north east cage on a bearing of 21. 7° G, the longest axis of the depositional footprint. A convergence angle of 1. 26° has been applied in reporting the transect bearing relative to True North. Transect and sampling station information is presented in Table 6, Figure 3 and Figure 5.
Table 6 Primary sampling transect
Primary transect ( T1) Start position 60045' 14. 7662" N, 0° 47' 56. 4771" W [ HP 65558 08492] Bearing 21. 7° G/ 22. 96° T Sampling station ID S1 S2 S3 Distance from cage edge ( m) 47. 9 57. 9 67. 9
NGR HP 65576 08536 HP 65580 08546 HP 65583 08555
60 45 16. 1977 N 60 45 16. 4944 N 60 45 16. 7912 N Latitude/ Longitude ( WGS84) 0° 47' 55. 2531" W 0° 47' 54. 9984" W 0° 47' 54. 7437" W
Depth ( m CD) 10. 5 9. 9 9. 3
Modelled ITI 21. 3 30. 0 43. 7
ITI Flux 27831 49 22261 37 16691 25 11121 13 5551
2. 0 3. 0 8. 0 13. 0
Bakhy
Figure 3 Cross section through the primary transect.
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A secondary transect has been proposed on the northern cage group originating from the north east cage on a bearing of 68. 6° G, the residual current direction of the near seabed layer. The transect detailed below is to be sampled only in the event that sampling along the primary transect is not possible. A convergence angle of 1. 17° has been applied in reporting the transect bearing relative to True North. Transect and sampling station information is presented in Table 7, Figure 4 and Figure 5.
Table 7 Secondary sampling transect
Secondary transect ( T2) Start position 60° 45' 14. 7662" N, 0° 47' 56. 4771" W [ HP 65558 08492] Bearing 68. 6° G/ 69. 77° T Sampling station ID S4 S5 S6 Distance from cage edge ( m) 46. 4 56. 4 66. 4
NGR HP 6560108509 HP 6561108512 HP 65620 08516
60045' 15. 2859" N 60045' 15. 4016" N 60045' 15. 5132" N Latitude/ Longitude ( WGS84) 0047' 53. 6027" W 0047' 52. 9832" W 0047' 52. 3639" W
Depth ( m CD) 10. 7 10. 4 10. 0
Modelled ITI 14. 6 30. 0 40. 9
ITI Flux 27831 49 22261 37 16691 25 11121 13 5551
2. 0 3. 0 8. 0 13. 0
Bakhy
Figure 4 Cross section through the secondary transect.
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Figure 5 illustrates the initial deposition of material at maximum biomass on the spring tidal scenario ( Run 8).
465000 465100 465200 465300 465400 465500 465600 466700 466800
LEGEND
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13afta Isle- BcI1stF1- -$ Transect
Sampling
Figure 5 Initial solid deposition at Balta Isle at maximum biomass illustrating the primary and secondary transects and sampling stations.
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4. 1. 2 Fate Assessment of Exported Material The activity of the cage bottom and near seabed waters is more important than that of surface water when considering the resuspension and subsequent dispersion of organic material. Resuspension of the sediments occurs when current speeds exceed 0. 095m/ s. Particulate matter is eroded from the seabed, re- entering the water column until near seabed currents fall below the threshold for deposition. Resuspension can effectively disperse matter away from where it initially settles with this material often exported from the immediate vicinity of the cages into receiving waters beyond the model domain. At the Balta Isle site current speeds exceeding 0. 095m/ s occurred in near seabed currents for 89% of the survey period classifying the site as partially resuspensive.
Sites are categorised as quiescent, weakly, moderately or strongly flushed depending on average current speeds. Quiescent periods are occurrences of slack water with a flow that falls below 0. 03m/ s. The percentage of records that falls within this range determines whether the site is slightly, moderately or highly quiescent. The hydrographic data indicates that the site is moderately flushed based on current speed with mean current flow for the cage bottom and near seabed waters being 0. 061m/ s. Quiescent periods accounted for 17% of the hydrographic survey period at Balta Isle therefore the site is classified as slightly quiescent.
With the site being classed as partially resuspensive, moderately flushed and slightly quiescent it was expected that some material will be transported away from the site. Following the modelling work AutoDEPOMOD reported that 18% of the material released would be exported from the model domain. If the calculated daily feed input at maximum biomass is constant over one year this equates to 160, 709kg solids/ yr.
The fate of this material is assessed with respect to:
Near seabed residual current record The direction of the residual current in the near seabed layer was 68. 6° G at 0. 037m/ s with a major axis of 5°. The cumulative vector plot shows a net movement to the north east in all three layers. The scatter plot for the near bed layer shows greatest movement of particles to the north and east. Currents exceeding the resuspension threshold occurred in 115 distinct events throughout the survey period. The resuspension events can be split into two groups, events associated with movement of particles to the north ( 275- 95°) which made up 87. 8% of the events and events associated with movement of particles to the south ( 95-
275°) which made up 12. 2% of the events. Stronger currents were associated with movement to the north around high water. The majority of the material will be moved in a north or north east direction. Figure 6 shows the direction frequency of all current profiles exceeding the threshold for resuspension while Figure 7 is a plot of all resuspensive currents against depth.
Cooke Aquaculture Scotland Page 12 1 27 25
20
15
10
5
0
102030405060708090100110120130140150160170180190200210220230240250260270280290300310320330340350360Frequency > 0.095m/
15. 0 0.195
14. 5
14. 0 0. 145
13. 5
0. 095 13. 0
12. 5
16. 0 12. 0
Direction ( Grid)
15. 5 s-1Current Balta Isle Technical Modelling Report May 17, 2017
material will be transported to the north and north east towards the north mouth of Balta
Sound and the shoreline at Balta.
Potential major depositional areas Given the low amount of export there are unlikely to be any major depositional areas. Exported material is expected to move north through the north channel of Balta Sound before being dispersed rapidly in the open water out with Balta Sound.
Potential receiving area On the assumption that the feed input at maximum biomass is constant through the year the exported material would be 160, 709kg solids/ yr. If this material were dispersed evenly to the flux equivalent to an ITI score of 30 (" changed" benthic communities) it would require an area of 0. 84k M2 which is not considered significant in regards to the direction of transport of the exported material towards an energetic water body to the north of Balta Sound.
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4.2 In -feed treatments
In -feed treatments are used to control sea lice in marine salmon farms by coating the daily feed ration with medicine. The in -feed treatment Slice ( active ingredient Emamectin benzoate) requires deposition modelling using AutoDEPOMOD to predict the chemical accumulation on the seabed beneath the cages associated with faecal particles and treated waste feed pellets. Environmental Quality Standards ( EQS) are applied over two areas on the seabed beneath the cages. The near field Allowable Zone of Effects ( AZE) is equivalent to the area bounded by a margin 25m from the edge of the cages with the EQS in place to protect sediment worker species below and in close proximity to the cages. The far field AZE is equivalent to the area bounded by a margin 100m from the edge of the cages with the EQS used to protect species at greater distances from the cages.
4. 2. 1 Slice — Emamectin Benzoate Environmental Quality Standards for Slice: Far field AZE: A limiting concentration has been set at 0. 763µg/ kg wet weight sediment, compliance to which will determine the quantity of chemical administered to the stock. Near field AZE: A trigger value has been set for this area of 7.63µg/ kg wet weight sediment, which if exceeded will trigger a requirement for enhanced benthic monitoring. Total Allowable
Quantity (TAQ)The purpose of the consent modelling process is to determine the maximum amount of Slice that can be released at the site during any two year production cycle whilst adhering to statutory Environmental Quality Standards. This quantity of chemical is known as the Total Allowable Quantity ( TAQ)and must not exceed an upper" limit" which is defined by SEPA as the amount of chemical that would treat the equivalent of five times peak biomass. The Total Allowable Quantity is the maximum amount permitted in a single production cycle, which if discharged in a single 7 day treatment will achieve compliance with the far field sediment quality standard. Through iteration the quantity of chemical is determined where the deposition at a concentration > 0. 763µg/ kg wet weight sediment has an area equal to the
AZE (+/-1%).AutoDEPOMOD was run initially for a TAQ sufficient to treat five times the consented biomass. Annual feed load was calculated as 5,586.1t/ yr. Fate of the chemical material exported from the model domain was assessed with the amount of medicine mass lost from the model domain calculated by the equation: Mlost- s=Mstart (
X 0. 74)Mend —Where: Mstart is
the initial quantity delivered to the stock Mend is the quantity in the model grid at the end of the run Most -s is the amount of chemical exported from the grid A factor of 0.74 incorporates cumulative excretion and decay until day 118.Cooke Aquaculture Scotland
Page 15 1 27 Balta Isle Technical Modelling Report May 17, 2017
Using the initial TAQ of 3, 823. 4g of emamectin benzoate required to treat 10, 924t ( 5x maximum biomass) of fish, the amount remaining in the grid is 2, 309g, therefore according to the equation above 520. 32g ( 13. 61%) will be exported from the model domain and 994. 08g will have degraded to non- toxic by- products.
The fate assessment of the exported material:
The near seabed residual current record Resuspension events at the site were present throughout the survey with the majority of the material transported to the north and north east towards the north mouth of Balta
Sound and the Balta shore. Approximately 13. 6% of Slice is exported from the model grid however with the dynamic nature of the receiving waters to the north of the site material should be dispersed rapidly. The Balta Isle site would be considered as topographically unconstrained as per the SEPA guidance " In -feed consent limits at dispersive sites v3". In this case if the material exported was dispersed evenly to the far -field EQS concentration, the area affected should not exceed 10k M2.
Potential for cumulative deposition There are three other fish farms located within Balta Sound. Baltasound Harbour is located near the head of Balta Sound, Swarta Skerry is sited off the east coast of Unst at the opposite side of the sound to Balta Isle and Huney is located south of Balta Isle between Unst and the island of Huney. The Huney site however has not been in use since 2003. None of the three sites in Balta Sound are consented for Slice therefore there will be no areas of cumulative deposition. In addition Cooke Aquaculture Scotland intend to relinquish the consents for Baltasound Harbour, Swarta Skerry and Huney if the application for Balta Isle is successful.
Concentration in the receiving water in relation to the far field EQS To dilute the exported material to 0. 763µg/ kg litre would require a volume of 6.81 x 105 m3, which is equivalent to an area around the site with a radius of 145. 17m using the average water depth of the model grid.Area
of impact if dispersed to the far field EQS Assuming a standard mixing depth of 5cm and a wet sediment density of 2,416kg/ m3 the material exported would require 5.65km2 of seabed to be dispersed evenly to the far field EQS concentration. There was some deposition present on the coastline of Balta to the east of the site however after discussions with Sepa a blanking file to remove this deposition was deemed unnecessary due to the Balta Isle site obtaining a pass at the maximum TAQ of 5x maximum biomass and the area of impact being well within the 10km2 allowed area for dispersal to the far field EQS. On
the basis of this fate assessment it is recommended that Slice should be consented at the quantities derived through modelling. Cooke
Aquaculture Scotland Page 16 1 27 1208600
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7.63 1208200
1208000
1207800 Northings0. 76 ug/kg sediment
465000 465200 465400 465600 465800 466000
Eastings 4000000
3500000
3000000
2500000
2000000
1500000
1000000
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0 0 20 40 60 80 100 120 140 160 180 200 220CumulativeDischarge Mass (mg)Time (Days From
Start of Treatment) Treat +Faecal Accumulation ( No Decay) Treat +Faecal Balta Isle Technical Modelling Report May 17, 2017
4. 3 Bath treatments
Bath treatments are topical treatments administered by fully enclosing a cage with a tarpaulin sheet. Concentrations in the plume around the farm after treatment are compared with EQS standards set by SEPA to determine the quantity of chemical that can be released in a 3 hour period.
The bath treatments Salmosan Vet ( active ingredient Azamethiphos), Excis ( active ingredient Cypermethrin) and Alphamax ( active ingredient Deltamethrin) require dispersion modelling to predict the concentration in the water column after release. Results from the Bath model using the " strait" scenario have been provided below.
4. 3. 1 Salmosan Vet —Azamethiphos Salmosan Vet will now be modelled in place of the original Salmosan product to comply with the European Medicines Agency residue guidelines. Salmoson Vet is a new improved formulation using the chemical ingredient azamethiphos and only differs slightly from the original Salmosan product.
Appendix 1 outlines the reasons why Cooke Aquaculture Scotland are making the crossover from using Salmosan to using Salmosan Vet.
More information on the product can be found at http:// salmosan. net/
Short term (3 hours) and long term ( 24 hours) modelling of azamethiphos has been undertaken for the site.
Short term model The total quantity of azamethiphos that can be administered in a 3 hour period without exceeding the EQS is 130. 58g or an Equivalent Treatable Volume of 1, 306m3. This quantity of chemical would treat 1 cage with a net depth of 1. 64m. Treatment of 1 cage would result in a 3 hour post treatment concentration of azamethiphos in the plume of 249. 9ng/ I. This is within the 3 hour EQS of 250ng/ I.
Lone term model The initial treatment regime determined by the short term model, 1 cage with a net depth of 1. 64m treated every 3 hours, is tested against the 72 hour standards using the " strait" scenario. If the 72 hour model predicts this regime will breach the criteria, the quantity of azamethiphos released in a 24 hour period is reduced until compliance with these standards is attained. This is achieved through increasing the treatment interval, reducing the number of treatments per day and reducing the quantity of chemical required for a single treatment. Once a treatment regime that passes environmental standards is found then the 72 hour model output is converted to a 24 hour limit.
Through iteration a treatment scenario using 1 cage with a net depth of 1. 37m per treatment event, with 1 treatment per day allows up to 109g of azamethiphos to be used in any 24 hour period, equivalent to a treatable volume of 1, 090m3. Treatment of the whole site would take 20 days.
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The total area of the patches released where the concentration exceeds 40ng/ I must not be greater than 0. 5km2. Within the patch the peak concentration must be less than 100ng/ I. Using the total allowable quantity of 1098 the results indicate that following 72 hours the peak concentration within the patch would be 98ng/ I while the total area of the patches would be 0. 48km2.
4. 3. 2 Excis - Cypermethrin Cypermethrin has very low water solubility and is readily adsorbed by organic and solid matter. Consequently only the short term model is required to determine compliance with the EQS.
The total quantity of cypermethrin that can be administered in a 3 hour period without exceeding the EQS is 23. 64g. This quantity of chemical could treat 3. 6 cages with a net depth of 1. 64m or an Equivalent Treatable Volume of 4, 727m3. Treatment of 3 cages would result in a 3 hour post treatment concentration of cypermethrin in the plume of 13. 2ng/ I. This is within the 6 hour EQS of 16ng/ I.
4. 3. 3 Alphamax - Deltamethrin Deltamethrin is very similar to cypermethrin and is also readily adsorbed by organic and solid matter therefore only the short term model is required to determine compliance with the EQS.
The total quantity of deltamethrin that can be administered in a 3 hour period without exceeding the EQS is 8. 86g. This quantity of chemical could treat 3. 4 cages with a net depth of 1. 64m or an Equivalent Treatable Volume of 4, 432m3. Treatment of 3 cages would result in a 3 hour post treatment concentration of deltamethrin in the plume of 5. 4ng/ I. This is within the 6 hour EQS of 6ng/ I.
4. 3. 4 Alternative bath model — " Loch" scenario To include the Baltasound Harbour area the bath model was run again using the " loch" scenario.
Results generated from the model using the " loch" scenario for Cypermethrin and Deltamethrin were the same as those generated using the " strait" scenario.
Azamethiphos 3hr model only had one slight difference which was the 3 hour post treatment concentration of azamethiphos in the plume which was slightly lower at 249. 4ng/ I. The 24hr model for azamethiphos required a slightly shallower net to gain a pass. A treatment scenario using 1 cage with a net depth of 1. 28m per treatment event, with 1 treatment per day allows up to 101. 7g of azamethiphos to be used in any 24 hour period, equivalent to a treatable volume of 1, 017m3. Treatment of the whole site would take 20 days. Using the total allowable quantity of 101. 7g the results indicate that following 72 hours the peak concentration within the patch would be 47ng/ I while the total area of the patches would be 0. 48km2.
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5. Discussion
Biomass The modelled maximum biomass at the Balta Isle site is 2, 184. 8t at a stocking density of 19. 6kg/ m3. The model output for this site is representative of a partially resuspensive site with 18% of material exported from the model domain. It was concluded that the Mid hydrographic data collected in March 2016 would be most suitable for use when modelling the site due to the location of the current meter between the two cage groups, deeming it to be most representative of flow conditions around the site.
The site is located off the west coast of the island of Balta. There is evidence that the site is somewhat influenced by tides with current speeds increasing during the spring tide and decreasing during the neap tide. Wind had very little influence on currents at the site. Resuspension events moved the majority of the material north and north east. Stronger currents were associated with transport north around high water towards the north mouth of the channel between Unst and Balta which leads to open water where dispersal would be rapid.
Sampling stations were defined along the longest axis of the depositional footprint ( 21. 7° G) of the northern cage group at the cage edge, 10m inside the AZE, the AZE and 10m out with the AZE. Sampling transects were defined from the northern cage group instead of the southern cage group due to expected transport of material from the cages moving in a north and north easterly direction.
In -feed treatments Limitations are placed on the quantities of in -feed treatments which may be used at dispersive sites. These are sites with significant export of medicine residues from the model grid and where prevailing currents can reasonably be expected to prevent settlement for 3km. Where these criteria apply, in topographically unconstrained areas it is recommended that the mass of chemical exported from the far field allowable zone of effect is limited to that required to disperse over 10k M2 to the far field EQS concentration.
The TAQ for Slice was 3, 823. 4g which could be used to treat 10, 924t of fish ( 5x maximum biomass). Export from the site is low ( 13. 61%) which would require 5. 65km2 seabed area or 6. 81 x 105 m3 of water to disperse to the far field EQS. The near field average concentration for Slice did exceed the TAQ trigger value therefore extra monitoring will be required at the site.
Bath treatments Using the " strait" scenario results from the 3 hour model for azamethiphos indicate that 130. 58g can be used to treat a volume of 1, 306m3, which would be sufficient to treat 1 cage at a treatment net depth of 1. 64m. To achieve compliance with the long term EQS, up to 109g of azamethiphos can be administered in any 24 hour period. This would allow 1 cage, with a net depth of 1. 37m to be treated in 24 hours. Treatment of the whole site would be completed in 20 days.
Cooke Aquaculture Scotland Page 21 1 27 Balta Isle Technical Modelling Report May 17, 2017
Results from the 3 hour model for cypermethrin indicates a consent limit of 23. 64g sufficient to treat a volume of 4, 727m3. This quantity could be used to treat up to 3 cages with a net depth of 1. 64m in one 3 hour period. Treatment of the whole site could be completed within 2 days.
Results from the 3 hour model for deltamethrin indicate a consent limit of 8. 86g sufficient to treat a volume of 4,432m3. This quantity could be used to treat up to 3 cages with a net depth of 1. 64m in one 3 hour period. Treatment of the whole site could be completed within 2 days.
Of the bath treatments proposed for use both Excis ( cypermethrin) and Alphamax deltamethrin) are equally suitable as they allow for a quick treatment strategy and flexibility with regard to net depth reduction compared to Salmosan Vet ( azamethiphos). Following tarpaulin release on the ebb tide current data for the near surface layer indicates that the chemical plume would be transported north east towards Balta.
The bath model was run a second time using the " loch" scenario which included the Baltasound Harbour area as an alternative approach due to the whole area being classed as Balta Sound. The " strait" scenario was considered more suitable to use when modelling the bath treatments due to low export at the site and the transport of chemicals away from the site moving in a north east direction which would not have an impact on the waters to the west in Baltasound Harbour.
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Balta Isle Technical Modelling Report May 17, 2017
7. Appendices
7. 1 Appendix 1- Changeover to Salmosan Vet
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Refusing to go with the flow
Crowness Point, Hatston Industrial Estate, Kirkwall, Orkney KW15 1RG
Telephone 01856 876101— Fax 01856 873846
Reasons for the changeover from Salmosan to 5almosan Vet
Salmosan Vet is a newly formulated sea lice treatment using azamethiphos, which differs only slightly to the original Salmosan product. The small formulation change in Salmosan Vet from Salmosan is the removal of the 2% naphthalene sulphonic acid formaldehyde condensate which is now replaced with
2% extra Kaolin. The reason for removing the 2% naphthalene sulphonic acid formaldehyde condensate was to comply with European Medicines Agency ( EMA) Guidelines ( Commission Regulation No.: 37/ 2010) which states excipients without a maximum residue limit ( MRL), and not excluded from needing an MRL, cannot be used in medicines for food producing animals. Naphthalene sulphonic acid formaldehyde condensate does not have an MRL and cannot be excluded from having an MRL. Therefore it has been removed, making Salmosan Vet the only azamethiphos based medicine in Europe to comply with EMA residue guidelines.
Removing the 2% naphthalene sulphonic acid formaldehyde condensate has no effect on efficacy. It was an excipient from when the formulation was used in Crop Protection by Novartis. It was included as a wetting agent to stop drops forming on foliage, causing water droplets to spread out. There is no need for it in Salmosan ( Silicic acid is the dispersing agent for the formulation) and it has been shown through laboratory and field trials that there is no difference in how the two formulations behave. A chart is included below to show the dispersion comparison between Salmosan and Salmosan Vet.
iso
too
s
0 5 10 is 70 75 30 75 b { s s0 ss s0
MINUTES
Registered in Scotland No: 419789 Registered Office: Brodies, 2 Blytheswood Square, Glasgow, G24AD
Cooke Aquaculture Scotland Page 24 1 27 Balta Isle Technical Modelling Report May 17, 2017
Gbol AQtACULTURE SCOTLAND.—
Refusing to go with the flow
Crowness Point, Hatston Industrial Estate, Kirkwall, Orkney KW15 11RG
Telephone 01856 876101 — Fax 01856 873846
Efficacy in bioassays has also been tested. Efficacy of azamethiphos treatments are based on azamethiphos content as there is no ' formulation' left after dilution. Repeated bioassay results showed that there was never more than 7% variation in efficacy between pure azamethiphos,
Salmosan Vet, Salmosan and ' a competitor product'. Salmosan Vet had the highest efficacy of the products however statistical analysis determined no significant difference between any of the
treatments.
Extensive safety trials on the Salmosan Vet product have been carried out at higher temperatures to enable increased duration at increased temperature, resulting in there being no need for vets to work off label' with Salmosan Vet if running treatments of 60 minutes when temperatures are above 10° C.
The shelf life of the new Salmosan Vet product has also been increased from the original Salmosan
product to 24 months, demonstrating increased product stability.
To conclude the reasons for changing over to Salmosan Vet:
the product has greater practicality at higher temperatures leading to a greater efficacy
more effective treatments will lessen the chance of resistance
an increased shelf life leading to increased product stability
Salmosan Vet is the only compliant azamethiphos based medicine in Europe to comply with the EMA
residue guidelines.
Registered in Scotland No: 419789
Registered Office: Brodies, 2 Blytheswood Square, Glasgow, G24AD
Cooke Aquaculture Scotland Page 25 1 27 Balta Isle Technical Modelling Report May 17, 2017
7. 2 Appendix 2 - Data comparison of three Balta Isle hydrographic data sets ( 15 days).
The main hydrographic parameters have been outlined below for the near surface and near seabed layers for the North, Mid and South 15 day data sets. The locations of the three current meters have also been reported.
North Data Mid Data South Data
Near Near Near Near Near Near
surface seabed surface seabed surface seabed
Mean speed ( m/ s) 0. 041 0. 05 0. 064 0. 059 0. 067 O. OS4
Ranked percentage of 0. 030m/ s 41 25 15 19 23 34
Ranked percentage of 0. 045m/ s 63 49 34 38 40 54
Ranked percentage of 0. 095m/ s 97 93 86 89 1 79 86 Minimum speed ( m/ s) 0. 001 0. 002 0. 003 0. 003 0. 001 0
Maximum speed ( m/ s) 0. 147 0. 154 0. 281 0. 265 0. 304 0. 2S9
Residual speed ( m/ s) 0. 023 0. 036 0. 044 0. 037 0. 046 0. 036
Residual direction (' Grid) 346 317 64 69 26 16
Major axis of tidal ellipse (' Grid) 33S 32S 10 S 20 10
Parallel residual ( m/ s) 0. 022 0. 036 0. 026 0. 017 0. 046 0. 036
Normal residual ( m/ s) 0. 004 0. 005 0. 035 0. 033 0. 005 0. 004
Parallel tidal amplitude ( m/ s) 0. 049 0. 051 0. 079 0. 072 0. 091 0. 077
Normal tidal amplitude ( m/ s) 0. 033 0. 035 0. 041 0. 038 0. 043 0. 036 Tidal current amplitude anisotropy 1. 48 1. 46 1. 92 1. 9 2. 14 2. 13
Current meter NGR 465574 1208384 465557 1208195 465517 1207986
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7. 3 Appendix 3 — Model outputs generated using the three Balta Isle hydrographic data sets.
The cage group set up used in AutoDEPOMOD for all model runs was:
20 cages/ two cage groups - 10x100m/ 5x2 cage configurations/ 7m nets
Orientation: North group - 319° / South group - 50°
Site centre North group - HP 65603 08370 / South group - HP 65546 07951
The table below shows the maximum biomass limits achieved using the three different hydrographic data sets, looking at three different grid sizes.
Grid size ( m) Biomass ( t) Stocking ITI Export (%) density (kg) North 50 1571. 8 14. 1 9. 9 5
Mid 50 1772. 4 15. 9 9. 9 18
South 50 2084. 5 18. 7 9. 9 31
North 60 1928. 5 17. 3 9. 9 5
Mid 60 2184. 8 19. 6 9. 9 18
South 60 2586. 1 23. 2 10 32
North 70 2329. 8 20. 9 9. 9 5
Mid 70 2641. 9 23. 7 9. 9 18
South 70 3098. 9 27. 8 10 31
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