NUTRIENT ASSESSMENT REPORT BALTA ISLE CAR/ L/ Report date: 1. Author: Cooke Aquaculture. Scotland. Orkney, Hatston Industrial Estate,

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1 NUTRIENT ASSESSMENT REPORT BALTA ISLE CAR/ L/ Author: Report date: 1 Cooke Aquaculture Scotland Crowness Rd, Hatston Industrial Estate, Kirkwall, Orkney, KW15 1RG T: + 44 ( 0) www. cookeaqua. com

2 Balta Isle Nutrient Assessment Report May 17, 2017 Table of Contents Introduction... 3 Background... 4 Sitedetails... 5 NutrientModelling... 7 ECE modelling methodology... 8 ECECalculations... 9 Results Discussion Mitigation References Cooke Aquaculture Scotland Page

3 Balta Isle Nutrient Assessment Report May 17, 2017 Introduction As part of the scoping and screening process, in relation to a proposed increase in biomass at the Balta Isle site in Shetland, Cooke Aquaculture Scotland have carried out an assessment of the potential water column impacts. Details of the predicted nutrient enhancement likely to result from the discharge of the finfish site are provided as well as taking into account any cumulative impacts from other sites in the surrounding area. An Equilibrium Concentration Enhancement ( ECE) assessment using the semi -enclosed water model described by Gillibrand ( 2002) will be used to assess nutrient enhancement at the Balta Isle site. Cumulative impacts for the area will be assessed to include all sites consented in Balta Sound however Cooke Aquaculture Scotland proposes to relinquish all other consents in Balta Sound to accommodate the increased biomass proposed at Balta Isle. Cooke Aquaculture Scotland Page

4 Balta Isle Nutrient Assessment Report May 17, 2017 Background Fish farms release nutrients as dissolved inorganic nutrients through excretion from the fish ammonia and phosphate), particulate organic nutrients through defecation, and dissolved organic nutrients through resuspension from the particulate fractions. The majority of the nitrogen ( N) wastes are released to open waters ( 68% of total) in the form of ammonia whereas the majority of the phosphorus ( P) is accumulated in sediments ( 63%). Dissolved inorganic nutrients are rapidly assimilated by phytoplankton and bacteria, and are then transferred to the higher trophic levels in the planktonic food web ( Olsen and Olsen, 2008). These nutrients can enhance the growth of marine plants and algae within the water column. High nutrient levels may lead to algal blooms and depletion of oxygen in the water column however it is not easy to identify the causal links of harmful algal blooms, with impacts from fish farms on productivity yet to be demonstrated, as dilution at marine sites is generally rapid. In the marine environment nitrogen is typically a limiting nutrient so its addition will dictate the amount of primary production ( algal growth) however phosphorous is not considered a limiting nutrient for phytoplankton in marine waters and therefore is of less importance than nitrogen ( Environmental Assessment Office, 1997). The Scottish Executive Review of environmental impacts of aquaculture concluded that the present level of fish farming is having only a small effect on the numbers and growth rate of phytoplankton and that this effect should not be a cause of concern except in poorly flushed areas or areas of high farm density ( Scottish Executive, 2002). It is also recognised in many areas, especially rural areas, that nutrient inputs from agricultural land well exceeds those from fish farming operations. A number of steps have been taken by the industry in recent years to reduce nutrient release into the marine environment through improvements in husbandry practices, feed technology and feed quality, however the continuing increase in total production means that the release of nutrients to the sea from aquaculture has also increased ( Gubbins, 2003a). Therefore monitoring nutrient levels around fish farms is important to ensuring impacts on the water column and organisms present are reduced. Cooke Aquaculture Scotland Page

5 Balta Isle Nutrient Assessment Report May 17, 2017 Site details The Balta Isle fish farm is located off the west coast of the island of Balta. The development is sited to the east side of Balta Sound, a water body which runs between the islands of Unst and Balta. The infrastructure proposed for the site is 20 cages, 100m in circumference arranged in two groups of 5x2 cage configurations. The north group is orientated to 3190 and the south group is orientated to 50. Grids will be 60m2, with a net depth at the site of 7m. An increase in biomass is proposed at the site from 450 tonnes to 2, tonnes. There are four fish farms including the Balta Isle site in Balta Sound which will be considered in the cumulative assessment. If permission is granted for the proposed increase in biomass at Balta Isle the consents for the three other sites in Balta Sound will be surrendered. Details and locations of the four sites in Balta Sound can be found in Table 1 and Figure 1. Table 1 Details of the fish farm sites in Balta Sound. CAR licence number Site name Maximum biomass tonnes) Site centre position WGS 84 NGR Distance to Balta Isle ( km) CAR/ L/ Balta Isle 2, * 60o ' N ' W ' N CAR/ L/ Swarta Skerry ' W ' N CAR/ L/ Huney ' W Baltasound ' N CAR/ L/ Harbour ' W Proposed new biomass, previous consented tonnage 450 tonnes. Cooke Aquaculture Scotland Page

6 I ; _, _:. -., t a n ', Balta Isle Nutrient Assessment Report May 17, 2017 i + tel. 4 r_.....,. r. n,,`:', 7i+r`:..":... d '., w Bahas ouncl Harbour p,.'....!. Baha Isle ;" I' 5wart a Skerryy^, ^ ' Isr - U i N S T BAL' IAtSO 1ND a 4 r. ' a' s? F '.., tt xyr Huney xr`. Admiralty charts: Copyright: Crown Copyright/ SeaZone Solutions. All Rights Reserved. Licence No ( 2017). Not to be used for Navigation. Figure 1 Fish farm locations in Balta Sound. Cooke Aquaculture Scotland Page

7 Balta Isle Nutrient Assessment Report May 17, 2017 Nutrient Modelling Nutrient enhancement of a water body can be estimated by using two types of models. The first is used for assessing semi -enclosed water bodies and is described by Gillibrand ( 2002). This model is a technique used by Marine Scotland in the ' Locational Guidelines for Authorisation of Marine Fish Farms in Scottish Waters' issued to aid marine fish farm planning. This model is based on a semi -enclosed loch scenario with exchange of the water body achieved through the ebbing and flooding tide to the extent that constant nutrient input achieves a steady state concentration with tidal export and replenishment. The second model is used for assessing sites which are not located within semi -enclosed water bodies described by Gillibrand ( 2006) and is an alternative approach to calculating the ECE for open water sites. Length and width of nutrient plumes are defined by parameters extracted from hydrographic survey data where current velocities have been resolved to along shore and across shore components. The open water model is dependent on clearly defined tidal constituents to calculate the plume dimensions and volume on a tidal excursion. Hydrographic data recorded at the Balta Isle site illustrates an area not strongly influenced by tides with relatively low current speeds and a small proportion of material ( 18%) transported away from the site. Based on current speed analysis the site is classified as moderately flushed, slightly quiescent and partially resuspensive. A lack of bidirectional currents through the water column and an amplitude anisotropy value around 1 is further evidence that there is a weak tidal influence at the site. The Balta Isle site is located within Balta Sound which is listed as a designated area in Marine Scotland Science ' Locational Guidelines for Authorisation of Marine Fish Farms in Scottish Waters'. Taking into account the hydrographic data for the site and the designation of Balta Sound by Marine Scotland Science as a semi -enclosed water body the ECE assessment methodology described by Gillibrand ( 2002) is the most appropriate to assess the nutrient enhancement of the Balta Isle site. Cooke Aquaculture Scotland Page

8 Balta Isle Nutrient Assessment Report May 17, 2017 ECE modelling methodology The ECE model is a simple box model used to predict the level of enhancement of soluble nutrient nitrogen from fish farming sources, treating nitrogen as a conservative substance. The model is a function of the flushing rate of a sea loch or voe, nitrogen source rate and total consented biomass within a defined area. The nutrient considered by the model is nitrogen, mainly in the form of dissolved ammonia but also accounting for nitrogen emitted as particulate waste and re -dissolving into the water column from the seabed. This is equivalent to considering that seabed conditions at farms are generally not deteriorating with time. The combined source of nitrogen from dissolved and particulate wastes is 48. 2kg N per tonne of salmon produced. This value is derived from a mass balance model used to estimate the release of dissolved and particulate nitrogenous waste from cultivated salmon ( Davies, 2000). Such an estimate is dependent on details such as stocking, feeding and harvesting strategies employed during cultivation. This information was derived from the records of a major salmon producer in Scotland averaged over a large number of their on -growing sea cage sites. Total nitrogen discharge rate is therefore the sum of the dissolved and particulate rates. The ECE models predict the relative levels of nutrient enhancement. The results of the model is scaled 0-5 to give a nutrient enhancement index ( Table 2). Areas with higher ECE values are considered to be the most environmentally sensitive to further fish farming development due to high predicted levels of nutrient enhancement. Table 2 Index of nutrient enhancement, derived from predicted levels of equilibrium concentration enhancement ( ECE) for nitrogen. Predicted ECE for nitrogenous nutrients arising from fish farming ( µmol 1-1) Nutrient enhancement index Cooke Aquaculture Scotland Page

9 m3) m3 m3 Balta Isle Nutrient Assessment Report May 17, 2017 ECE Calculations The calculations used to determine the ECE values for Balta Sound using the semi -enclosed water body model are detailed in the ' Scottish Executive Locational Guidelines for Fish Farming: Predicted Levels of Nutrient Enhancement and Benthic Impact' ( Gillibrand, 2002). A summary of the calculations used to assess nutrient impact are detailed below. The flushing time of the water body can be calculated by assuming that the water volume is replaced by the volume of water entering and leaving on each tide, the " tidal prism" Edwards and Sharples, 1986). Flushing time ( TF) in days is calculated using the equation: TF = 0. 52V 0. 7A. R Where: V is the volume of the water body ( A is the surface area of the water body ( m2) R is the tidal range ( m) The factor is the number of days per tidal cycle ( 1 tidal cycle = hours = days) and the factor 0. 7 approximates the mean tidal range from the spring tidal range, R Edwards and Sharples, 1986). Flushing rate is calculated using the equation: Q = 365. V TF The factor 365 converts the units from d- 1 to quantity of water that is exchanged over a year. y- 1. The flushing rate is now the total The ECE model uses the simple equation: ECE = S. M/ Q Where: M is the total consented biomass of all the finfish farms in the water body ( tonnes) Q is the flushing rate of the water body ( may 1), calculated by hydrographic characteristics of the system S is the source rate (total discharge of nutrient nitrogen kg tonne production) Cooke Aquaculture Scotland Page

10 m3 Balta Isle Nutrient Assessment Report May 17, 2017 To standardise the source rate with the calculations used in the Locational Guidelines the nitrogen discharge of kg N per tonne of production is used, derived from Davies ( 2000). The ECE units were converted from kg/ to µg/ I ( 1kg= 1, 000, 000µg) and then finally to µmol/ I since measurements of dissolved nutrients are traditionally presented in these units. To convert from µg/ I to µmol/ I the ECE value was divided by the molecular weight of nitrogen ( 14g). Cooke Aquaculture Scotland Page

11 Balta Isle Nutrient Assessment Report May 17, 2017 Results Data inputs for the ECE model have been obtained from Marine Scotland Science ' Locational Guidelines for Authorisation of Marine Fish Farms in Scottish Waters' ( March 2017). These include the area, volume, tidal range, flushing time and flushing rate of Balta Sound. The production cycle for the Balta Isle site is 22 months with 2 months fallowing. To adopt a precautionary approach and to follow the methods detailed by Gillibrand ( 2002) the source of nitrogen from dissolved and particulate wastes was set at kg Nitrogen per tonne of salmon produced. The ECE modelling parameters are presented in Table 3 with Balta Sound, the Locational Guideline area defined by Marine Scotland Science used for the ECE calculation, illustrated in Figure 2. Table 3 Balta Sound ECE model parameters Area ( km2) A 3. 7 Volume of voe ( Mm3) V Tidal range ( m) R 1. 9 Flushing time (d) Tf 3. 3 Flushing rate ( Mm3/ yr) Q 3, 375 Nitrogen per tonne production ( kg) S Cooke Aquaculture Scotland Page

12 Balta Isle Nutrient Assessment Report May 17, AQLL CUL Sc-o-rLANPA Refio. ins rf, g'. W!$ 6 Thr fl., Klomebns Copyright and d BIB b13surfghtlid16 Contains DS Figure 2 Balta Sound Locational Guideline area Cooke Aquaculture Scotland Page

13 Balta Isle Nutrient Assessment Report May 17, 2017 As stated in Marine Scotland Science ' Locational Guidelines for Authorisation of Marine Fish Farms in Scottish Waters' ( March 2017) a maximum biomass of 1, 220 tonnes can be produced from the four sites in Balta Sound currently. With the increase in biomass at the Balta Isle site this increases to 2, tonnes. Three ECE modelling outputs have been reported in Table 4. The first is for the current tonnage in Balta Sound, the second is for the proposed new tonnage to include an increase in biomass at Balta Isle and the third is only taking into account the proposed new biomass at Balta Isle as the other three sites consents will be revoked if the new development at Balta Isle is approved. Table 4 Balta Sound ECE model outputs ECE ( 1): All sites -current tonnage Total biomass ( t) M 1, 220 ECE ( µg/ I) ECE ( µmol/ I) Nutrient Enhancement Index 3 ECE ( 2): All sites -increased tonnage Balta Isle Total biomass ( t) M 2, ECE ( µg/ I) ECE ( µmol/ 1) Nutrient Enhancement Index 4 ECE ( 3): Balta Isle new tonnage only Total biomass ( t) M 2, ECE ( µg/ 1) ECE ( µmol/ 1) Nutrient Enhancement Index 3 Cooke Aquaculture Scotland Page

14 Balta Isle Nutrient Assessment Report May 17, 2017 The current predicted nutrient enhancement value for the Balta Sound area is µmol 1-1 equivalent to a nutrient enhancement index of 3. The value is at the lower end of index category 3 which ranges from 1 to 3 µmol/ l. The predicted nutrient enhancement value for the Balta Sound area will increase to µmol 1-1 equivalent to a nutrient enhancement index of 4, with an increase in biomass at the Balta Isle site. The value is just within index category 4 which ranges from 3 to 10 µmol/ l. If the new cage setup and tonnage proposed at Balta Isle is approved the licences of the other three sites in Balta Sound will be surrendered, therefore the predicted nutrient enhancement value for the Balta Sound area will be is µmol 1-1 equivalent to a nutrient enhancement index of 3. Cooke Aquaculture Scotland Page

15 Balta Isle Nutrient Assessment Report May 17, 2017 Discussion Due to the non -tidal nature of the current data recorded at the Balta Isle site and the designation by Marine Scotland Science of Balta Sound as a semi -enclosed water body the ECE model described by Gillibrand ( 2002) was deemed the most appropriate to assess nutrient enhancement of the Balta Sound area. The current predicted nutrient enhancement value for Balta Sound is µmol 1-1 when the four sites are stocked to maximum biomass ( 1, 220t), giving a nutrient enhancement index value of 3. When the increased biomass at Balta Isle is introduced to the area ( 2, t) the predicted nutrient enhancement value increases to µmol 1-1 and moves the area into nutrient enhancement category 4. As Cooke Aquaculture Scotland propose to surrender the licences for Baltasound Harbour, Swarta Skerry and Huney if the new development at Balta Isle is approved ( 2, 184.8t) then the predicted nutrient enhancement value for the Balta Sound area would be µmol 1-1. This would mean Balta Sound was ranked within nutrient enhancement index category 3, the same ranking as Balta Sound currently has. A category 3 rating is mid -way on the nutrient enhancement index scale therefore there will be some build- up of nutrients at the Balta Isle site however due to the location of the Balta Isle site to the east of Balta Sound, in a strait which discharges north and south to energetic open water it is not considered significant in terms of the current regime of the surrounding area. With the tidal nature of the waters out with Balta Sound and the direction of transport of material north and north east from Balta Isle, nutrients will be dispersed quickly out the north mouth of Balta Sound. Nutrient input to the waters around the islands of Unst and Balta from land run- off are considered relatively low, derived primarily from agriculture notably sheep farming. There will be some nutrient enrichment in the vicinity of the development due to nutrient release from the fish farm, but due to the hydrographic conditions of the surrounding area it is unlikely to lead to any environmental impacts. The majority of the effluent from the site will be dispersed in the energetic waters to the north of the site. Cooke Aquaculture Scotland Page

16 Balta Isle Nutrient Assessment Report May 17, 2017 Mitigation In order to minimise nutrient input from the Balta Isle site, measures are in place to reduce the amount of waste feed entering the water column and settling on the seabed. Improvements in feeding efficiency and feed quality could reduce waste entering the water column lowering the environmental impact. The sites within Balta Sound have relatively low tonnages with none of the sites historically producing maximum biomass during their production cycles. The Huney site has not been used since October The three other sites have been used within the last one to two years but have only produced collectively, approximately 50% of the maximum tonnage 505t) of the area. As the total tonnage being produced by the sites in Balta Sound is reduced there will be lower nutrient enhancement in the area. Monitoring will be carried out in accordance with SEPA water quality monitoring procedures throughout the production cycle to monitor nutrients entering the water column and to act as an early warning of a potentially harmful bloom. Cooke Aquaculture Scotland Page

17 Balta Isle Nutrient Assessment Report May 17, 2017 References Cooke Aquaculture Scotland ( 2016) Balta Island Hydrographic Survey Report 27/ 07/ 16) 2000). Waste production by farmed Atlantic salmon ( Salmo solar) in Scotland. ICES CM 2000/ 0: 01, 12 pp. Environmental Assessment Office ( 1997). Nitrogen as the limiting nutrient for eutrophication in coastal marine ecosystems. Evolving views over three decades ) Improving Assimilative Capacity Modelling for Scottish Coastal Waters: II. A Model of Physical Exchange for Open Water Sites. SAMS Marine Physics Report No ) Scottish Executive Locational Guidelines for fish farming: predicted levels of nutrient enhancement and benthic impact. Scottish Fisheries Research Report Number 63. FRS, Aberdeen. 2003a) OSPAR eutrophication assessment of aquaculture hotspots in Scottish coastal waters. FRS Marine Laboratory Collaborative Report 07/ 03, 149 pp. Marine Scotland Science ( March 2017) Locational Guidelines for the Authorisation of Marine Fish Farms in Scottish Waters. 2008) Environmental impact of aquaculture on coastal planktonic ecosystems. In: Fisheries for global welfare and environment. Proc Sth World Fisheries Congress 2008, Terrapub, Tokyo, p Scottish Executive, ( 2002). Review and Synthesis of the Environmental Impacts of Aquaculture, The Scottish Association for Marine Science and Napier University. 2001) The significance of residual currents in the interpretation of the EU Urban Wastewater Treatment Directive in coastal locations. Marine Pollution Bulletin, 40, Cooke Aquaculture Scotland Page