BIOMASS & SLICE MODELLING REPORT - SEPA

BIOMASS & SLICE MODELLING REPORT

Proposed Modification of Reintraid Pen Site, Loch a’ Chàirn Bhàin

Caerthann House

Gros venor Crescent

Connel

Argyll PA37 1 PQ

R e g i s t e r e d i n S c o t l a n d , N o : S C 1 7 5 0 8 7Tel: + E-mail:

TransTech Limitedwww.transtechltd. com

Prepared for:

Loch Duart Ltd

Badcall Salmon House

Scourie

Sutherland

IV27 4TH

Reintraid AutoDEPOMOD Modelling Report 2019v1 p2/15

Quality Assurance

The data used in this document and their input and reporting have undergone a qualityassurance review which follows established TransTech Ltd procedures. The informationand results presented herein constitute an accurate representation of the data collected.

TransTech is registered with SEPA for marine pen site Biomass (Ref: AMMR08v02) andChemical discharge modelling (Ref: AMMR08v01).

Document Details

Author:

Issue Date: 30 July 2019

Issue No: 2019v1


CONTENTS

1. Summary ................................................................................................................................................. 42. Introduction ............................................................................................................................................. 53. Reintraid site information for proposed modification .............................................................................. 64. Hydrographic data................................................................................................................................... 75. AutoDEPOMOD ...................................................................................................................................... 8

5.1 Site set-up ..................................................................................................................................... 85.2 Model grid generation ...................................................................................................................85.3 Benthic modelling .........................................................................................................................85.4 Slice modelling .......................................................................................................................... 10

6. Transects and sample stations ............................................................................................................ 12APPENDIX 1................................................................................................................................................ 14APPENDIX 2................................................................................................................................................ 15

List of Figures

Figure 1. Plot of AutoDEPOMOD benthic model Run 22 ........................................................................... 9Figure 2. Reintraid EmBz concentrations for Run 5 at 118 days ............................................................. 10Figure 3. Reintraid EmBz concentrations for Run 6 at 223 days ............................................................. 11Figure 4. Plot showing primary and spare transect positions and the respective sample stations .......... 13Figure 5. Cross sections of the primary and spare transects ................................................................... 13

List of Tables

Table 1. Spring and neap tides .................................................................................................................. 7Table 2. Intermediate spring and intermediate neap tides ........................................................................ 7Table 3. Current meter data summary ....................................................................................................... 7Table 4. Details and position of the three selected sample stations along the primary transect ............ 12Table 5. Details and position of the three selected sample stations along the spare transect ............... 12

List of Abbreviations

ADCP Acoustic Doppler Current ProfilerATT Admiralty Total TideAZE Allowable Zone of EffectsCD Chart DatumDFL Dawnfresh Farming LtdEmBz Emamectin Benzoate ( Slice) EQS Environmental Quality StandardsGMT Greenwich Mean TimeLST Lowest Spring TidemCD Metres below Chart DatumMSL Mean Sea LevelPE Pen EdgeSEPA Scottish Environment Protection Agency


1. Summary

1. This report has been prepared in order to meet the specific requirements of the ScottishEnvironment Protection Agency ( SEPA) for the assessment of applications for biomassconsent for salmonids held in marine pens.

2. The predictive model, AutoDEPOMOD, was used to determine the mass of EmamectinBenzoate ( Slice) at which the model passes, the permissible biomass and the AllowableZone of Effects (AZE) footprint for a proposed modification to Loch Duart’s Reintraid pensite.

3. The existing pen group consists of ten 24 m square pens (+ 2 swimthrough pens) in tworows orientated at an angle of 314o with a net depth of 11 m. The proposal is to add 2pens onto the existing configuration to provide 14 pens for fish production.

4. The site was remodelled as per the modelling upon which the current consent is basedbut with two pens added at the NW end of the group.

5. Hydrographic data and details of the pen layout were supplied to TransTech by LochDuart Ltd. The hydrographic data were approved by SEPA for modelling purposes in2009.

6. An AutoDEPOMOD benthic PASS prediction was obtained for 1455.1 tonnes at astocking density of 16.4 kg/m3.

7. For Emamectin Benzoate a PASS (118 days) and MAX (223 days) result was obtainedfor a mass of 795.8 g which equates to a treatable fish biomass of 2273.6 tonnes.

Benthic Pass = 1455. 1 TSlice Pass = 2273. 6 TStocking Density = 16.4 kg/m3


2. Introduction

This report has been prepared in order to meet the specific requirements of the ScottishEnvironment Protection Agency ( SEPA) for the assessment of applications for biomass consentand the consent to use chemical treatments against sea lice in marine salmonid farms. Thebiomass and chemical treatment levels must comply with the EQS that are in place to protect themarine environment.

Treatment of sea lice infestation in marine salmonid farms is currently carried out using twodifferent methods; the in-feed treatment Slice and bath treatments. Each method requires adifferent form of predictive modelling.

This report describes the results of predictive modelling for the permissible biomass, the AZEfootprint and Slice at the modified Reintraid site.

All hydrographic data used for the modelling was provided by Loch Duart Ltd. A hydrographicreport was produced by the Fish Vet Group, who carried out the ADCP deployment, and thedata were validated by SEPA for modelling purposes in 2009.

The methods described in this report closely adhere to those set out in Annex H of the SEPAFish Farming Manual ( 2005), and the results are reported to satisfy consent applicationrequirements.


3. Reintraid site information for proposed modification

Site details

Site name: ReintraidLocation: Loch a’ Chàirn Bhàin, Sutherland

Pen group details

Group centre position: 219139.1 E, 934034.7 NSE pen centre position: 219186.0 E, 933971.0 NNumber of pens: 14 (All 14 to be used for production)

Reported pen group configuration: 2 x 7Pen dimensions: 24 m squareNet depth: 11 mGrid size (x by y): 26 m x 26.5 mPen group orientation: 314º

Hydrographic data

Current meter position: 219161 E, 934031 N22.2 m from group centre)

Surface cell height above bed: 44.8 m (5.69 m below Spring Tide) Middle cell height above bed: 41.8 m (10.99 m below MSL) Bottom cell height above bed: 3.8 m

Depth at deployment site: 49.99 mCDCurrent meter averaging interval: 20 minRecord used for modelling (mid-range dataset): 15 days (03/04/09 00:00 – 18/04/09 00:00 GMT)

Additional data

Correction from Magnetic to Grid N: 2.0ºMean tidal level at site: Chart Datum + 2.8 m (Loch Nedd)


4. Hydrographic data

The dataset used in the modelling was collected over a 15 day period which incorporated boththe spring and neap components of the tidal cycle. Data were collected at 20 minute intervalsand copied into the temp-20min-HGv3.xls spreadsheet to generate the . dat files required byAutoDEPOMOD. Dates and times of spring and neap high waters ( table 1) were determinedusing the Admiralty Total Tide software ( ATT). Predictions were obtained for Loch Nedd58°14'N 5°10'W), the closest secondary port to the Reintraid site ( predictions based on

Ullapool).

Table 1. Spring and neap tides

Tide State Date Time (GMT) Level above CD

Spring HW 09/04/2009 06:32 4.9 m

Neap HW 17/04/2009 12:50 3.4 m

In accordance with SEPA modelling guidelines, current meter records to be used must start atapproximately midday ( GMT) on the day of the intermediate- spring and intermediate- neap tide. The date and time of the intermediate tides used in the hourly averaged records ( temp-20min-HGv3.xls files) are provided in table 2.

Table 2. Intermediate spring and intermediate neap tides

Tide Date Time (GMT) Hourly record

Predicted intermediate-spring 06/04/2009 11:40 84

Predicted intermediate-neap 14/04/2009 11:40 276

ATT Mean Sea Level (MSL) at the site is Chart Datum + 2.8 m and the lowest spring tide (LST) during the deployment is Chart Datum + 0.5 m. The raw current meter direction data werecorrected from magnetic north to grid north by subtracting 2.0º from the magnetic north directiondata.

The current meter data is summarised below:

Table 3. Current meter data summary

Period CellMeanspeedm/s)

Residualspeedm/s)

Residualdirection

ºGrid N)

03/04/09 00:00 - 18/04/09 00:00 GMT

Sub surface 0.061 0.035 314.1

Pen bottom 0.058 0.025 314.0

Near bed 0.033 0.002 27.1


5. AutoDEPOMOD

5.1 Site set-up

A new project was created in AutoDEPOMOD ( v2.0.52, 17-Aug-2005) and namedReintraid_2019v1. All of the relevant bathymetric and current meter files were set up in theirrespective directories and the pen information was entered into the corresponding FFMTv3.0.xlsfile. Pen positions and orientations were then checked by looking at the AutoDEPOMOD profileto ensure that they were in the correct position.

5.2 Model grid generation

The grid limits were set to 218740 E to 219740 E and 933700 N to 934700 N.

The .csv and an appropriate .ini file was saved into the \depomod\gridgen folder, as required byAutoDEPOMOD to generate the grid over which the pens would be laid. The grid was thengenerated with a cell size of 25 m and is shown in figure 1.

5.3 Benthic modelling

Run details used for biomass consent modelling:

No. of particles = Initial run 1 and refine at 10Convergence value = 1 tonnesNeap-Spring with automatically redo using Spring-Neap

Benthic Modelling Parameters:

Equally-distribute Biomass = ONStocking Density = 17.0 kg/m3Pen Volume Adjustment = 1

The model iterated to a PASS prediction of 1455.1 and 1480.1 tonnes for the neap-spring andspring-neap runs respectively ( Runs 22 and 27). The run with the smallest biomass/area ofimpact at the 30 ITI EQS was Run 22.

The maximum feed input for Run 22 (figure 1) was defined by the model as 10185.6 kg/day. The80% solids area was predicted as 37027 m2 with a flux in the area of 1541 g/m2/yr.

At the 1455.1 tonnes biomass, the pen area equivalent contour flux was 15486 g/m2/yr, at amean ITI of 1.0 with a pen area of 9090 m2. The benthic sampling area, where the ITI = 30.0, showed a flux of 191.8 g/m2/yr inside an area of 67123 m2. A summary of the results can befound in the Reintraid_2019v1_marine_sum_v3.xls Benthic Worksheet in appendix 1.


2 1 8 8 0 0 2 1 9 0 0 0 2 1 9 2 0 0 2 1 9 4 0 0 2 1 9 6 0 0

9 3 3 8 0 0

9 3 4 0 0 0

9 3 4 2 0 0

9 3 4 4 0 0

9 3 4 6 0 0

1 0 0

0

2

5

10

20

30

40

50

60

70

80

90

100

1 0 0 .0

1 9 1 .8

1 5 4 6 .7

5 0 0 0 .0

1 0 0 0 0 .0

1 5 0 0 0 .0

1 9 8 5 9 .3

2 0 0 0 0 .0

2 5 0 0 0 .0

3 0 0 0 0 .0

Figure 1. Plot of AutoDEPOMOD benthic model Run 22

N

Fluxg/m2/ yr)

Depth ( mCD)


5.4 Slice modelling

Run details used for Slice modelling:

Biomass = 7275.5 T (5 x maximum biomass) Food load = 3717.744 T over 12 monthsNo of particles = 10Convergence value = 1 TRun duration = 118 days followed by 223 days

EmBz EQS values:

Near Field = 7.63 µg/ kg wet weight sediment ( trigger) Far Field = 0.763 µg/ kg wet weight sediment

Slice Results

A blanking file was not required as deposition of EmBz is not predicted to overlay land.

AutoDEPOMOD predicted a 118 day PASS result ( Run 5, figure 2) for the far field EQS at abiomass of 2273.6 tonnes.

2 1 8 8 0 0 2 1 9 0 0 0 2 1 9 2 0 0 2 1 9 4 0 0 2 1 9 6 0 0

9 3 3 8 0 0

9 3 4 0 0 0

9 3 4 2 0 0

9 3 4 4 0 0

9 3 4 6 0 0

1 0 0 .0

0 .0

2 .0

5 .0

1 0 .0

2 0 .0

3 0 .0

4 0 .0

5 0 .0

6 0 .0

7 0 .0

8 0 .0

9 0 .0

9 9 .9

0 .7 6 3

7 .6 3 0

Figure 2. Reintraid EmBz concentrations for Run 5 at 118 days

Run 5 gave a recommended consent mass of 795.8 g EmBz. The predicted area inside the0.763 g/kg contour is 95340 m2, which is slightly larger than the 95190 m2 of the far field AZE.

At a biomass of 2273.6 tonnes, the model predicted a higher concentration than the near fieldAZE trigger value of 7.63 µg/ kg, where the mean concentration is 154.3 µg/ kg.

The mass balance of EmBz for Run 5 was predicted as 550 g, meaning that 4.89 % of the inputload is transported from the model grid as a result of resuspension.

N

EmBz Concentrationµg/ kg wet sediment)

Depth (m)


For the 223 day model run a MAX result was predicted for 2273.6 tonnes. This run is shown infigure 3.

2 1 8 8 0 0 2 1 9 0 0 0 2 1 9 2 0 0 2 1 9 4 0 0 2 1 9 6 0 0

9 3 3 8 0 0

9 3 4 0 0 0

9 3 4 2 0 0

9 3 4 4 0 0

9 3 4 6 0 0

1 0 0 .0

0 .0

2 .0

5 .0

1 0 .0

2 0 .0

3 0 .0

4 0 .0

5 0 .0

6 0 .0

7 0 .0

8 0 .0

9 0 .0

9 9 .9

0 .7 6 3

7 .6 3 0

Figure 3. Reintraid EmBz concentrations for Run 6 at 223 days

A summary of the in-feed EmBz results can be found in appendix 2Reintraid_2019v1_marine_sum_v3.xls).

N

EmBz Concentrationµg/ kg wet sediment)

Depth (m)


6. Transects and sample stations

Primary and spare sampling transects were created for the site ( tables 4 and 5) using BenthicRun 22.

Details of the primary transect:

Transect start co-ordinates ( PE) 219085.9 E 934104.6 N58 15.4972 N 05 05.1111 W

Transect bearing and length 314.0º Grid North and 203.5 mDepth (PE) 43.1 mCD

Table 4. Details and position of the three selected sample stations along the primary transect

1st StationEQS-10m)

S2

2nd StationEQS) S1

3rd StationEQS+10m)

S3

NGR Easting 219002.7 218995.5 218988.3

NGR Northing 934185.0 934191.9 934198.9

Latitude 58 15.5384 58 15.5419 58 15.5455

Longitude 05 05.1998 05 05.2075 05 05.2152

Distance from PE (m) 115.7 125.7 135.7

Depth (mCD) 38.3 38.8 39.3

Modelled ITI 27.5 30.0 32.1

Details of the spare transect:

Transect start co-ordinates ( PE) 219192.2 E 933965.4 N58 15.4249 N 05 04.9961 W

Transect bearing and length 134.0º Grid North and 202.4 mDepth (PE) 47.5 mCD

Table 5. Details and position of the three selected sample stations along the spare transect

1st StationEQS-10m)

S5

2nd StationEQS) S4

3rd StationEQS+10m)

S6

NGR Easting 219302.3 219309.5 219316.6

NGR Northing 933859.4 933852.4 933845.5

Latitude 58 15.3706 58 15.3670 58 15.3635

Longitude 05 04.8787 05 04.8710 05 04.8635

Distance from PE (m) 152.9 162.9 172.9

Depth (mCD) 42.7 42.6 42.4

Modelled ITI 26.6 30.0 35.0

The position of both the primary and spare transects and the relative sample stations in relationto the site are shown in figures 4 and 5.


Figure 4. Plot showing primary and spare transect positions and the respective sample stations

Figure 5. Cross sections of the primary and spare transects

The benthic sampling has been packaged in Reintraid_2019v1\depomod\mapping\XLS\ Reintraid_2019v1-BcnstFI-N-22_000.xls.

SPARE

PRIMARY


APPENDIX 1

Reintraid_2019v1 _marine_sum_v3.xls (Version 3.13) Benthic Worksheet

These are cornerpen centre positions


APPENDIX 2

Reintraid_2019v1_marine_sum_v3.xls (Version 3.13) Treatment Worksheet

BIOMASS & SLICE MODELLING REPORT - SEPA

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