Developing regional locational guidance for wave and tidal energyin the Shetland Islands

Jacqueline F. Tweddle n,1,2, iLaria Marengo 3, Lorraine Gray 4, Christina Kelly 5,Rachel ShucksmithNAFC Marine Centre, Port Arthur, Scalloway, Shetland Islands ZE1 0UN, UK

a r t i c l e i n f o

Article history:Received 7 March 2014Received in revised form3 May 2014Accepted 3 May 2014Available online 2 June 2014

Keywords:Marine spatial planningRenewablesRegional Locational GuidanceConstraint mappingCumulative constraintsIntegrated coastal zone management

a b s t r a c t

Marine renewables offer potential economic and environmental benefits, however there is a need toensure that the growth of this emergent industry considers existing features and users of the marineenvironment. There is a clear role for marine spatial planning to guide its future development. TheShetland Regional Locational Guidance is a sensitivity led approach to identifying the suitability of areasaround the Shetland Islands for renewable energy development and associated shore based infra-structure, and is an example of integrated coastal zone management. Working closely with localstakeholders was key to this process, which incorporates economic, environmental, social and culturaluses into one constraint model; constraint levels are set by local and societal values, rather thanmonetary equivalences. It has been successfully translated into policy within the Shetland Islands'Marine Spatial Plan, which will form supplementary guidance to the Shetland Islands Council'sforthcoming Local Development Plan. The policy integrates with GIS data without requiring the creationof ‘zones’, as was requested by local stakeholders, and allows for updating of the GIS spatial modelwithout requiring changes to the policy wording.

& 2014 Elsevier Ltd. All rights reserved.

1. Introduction

1.1. Marine spatial planning and the Shetland Islands'Marine Spatial Plan

Marine spatial planning (MSP) is defined as a ‘public process ofanalysing and allocating the spatial and temporal distribution ofhuman activities in marine areas to achieve ecological, economic,and social objectives that usually have been specified through apolitical process’ [1]. This can be achieved by applying an ecosystembased approach, as endorsed by the European Commission, to

integrated MSP and coastal zone management [2]. Experience hasindicated that the place-based nature of the ecosystem approach isan essential element in the planning process, and if not incorporatedappropriately can result in a predominantly sectoral approach topolicy formulation [3].

The Shetland Islands' Marine Spatial Plan (SMSP) [4] is an integratedapproach to marine management which steers away from the tradi-tional sectoral approach that has, until recently, been applied towardsmarine issues [5]. The SMSP provides a policy framework and baselinespatial data to guide the placement of marine developments within the12 nautical mile limit (Fig. 1). The policies and spatial data encompasseconomic, environmental, social and cultural uses and features. Theprimary focus of the SMSP is to provide more information to publicbodies that have responsibilities for marine and coastal planningfunctions, and to developers. The SMSP informs decision-making,guides priorities, and seeks to achieve a balance between nationaland local interests [4]. The SMSP is guided by a Steering Group,which comprises of decision-makers, regulators, non-GovernmentalOrganisations (NGOs), local industry and community representatives.

The SMSP provides a proactive approach to marine manage-ment, which aims to reduce conflicts and ensure a more equitablesituation both across and within different priorities of the marinearea. One way of ensuring this approach is by defining andanalysing future conditions for ocean space, which is consideredto be an integral step in the MSP process [1].

Contents lists available at ScienceDirect

journal homepage: www.elsevier.com/locate/marpol

Marine Policy

http://dx.doi.org/10.1016/j.marpol.2014.05.0110308-597X/& 2014 Elsevier Ltd. All rights reserved.

n Correspondence to: School of Biological Sciences, Zoology Building, Universityof Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK. Tel.: þ44 1224272693;fax: þ44 1224272861.

E-mail address: jftweddle@abdn.ac.uk (J.F. Tweddle).1 Present address: School of Biological Sciences, Zoology Building, University of

Aberdeen, Tillydrone Avenue, Aberdeen AB24 2TZ, UK.2 Present address: Marine Scotland, Marine Laboratory, PO Box 101, 375

Victoria Rd, Aberdeen AB11 9DB, UK.3 Present address: South Atlantic Environmental Research Institute, PO Box

609, Stanley Cottage, Stanley FIQQ 1ZZ, Falkland Islands.4 Present address: Marine Atlas Consultants, 31 David Street, Inverbervie, Nr

Montrose DD10 0RR, UK.5 Present address: School of Planning, Architecture and Civil Engineering,

Queen's University Belfast, David Keir Building, Stranmillis Road, Belfast BT9 5AG, UK.

Marine Policy 50 (2014) 53–66

1.2. Marine renewables

Over the last decade, the marine renewables industry in Scot-land has been subject to significant research and development

investment, driven by increasing concerns over climate changeand energy security. The Scottish Government has set a target of30% of total energy demand being met by renewable sources by2020, to be achieved by renewables satisfying 100% of electricity

Fig. 1. Location map of the Shetland Islands, the most northerly islands of the United Kingdom. The spatial extent of The Shetland Islands' Marine Spatial Plan (12 nauticalmiles out from Mean High Water Spring) is marked in grey. Map not to be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011).Contains UKHO data© Crown copyright and database rights.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–6654

demand, and 11% of heat demand [6]. It is anticipated that marinerenewable energy sources (tidal and wave power) will play animportant role in achieving these objectives.

1.3. Shetland and marine renewable energy developments

The marine environment is of high economic value to Shetland.The Shetland Islands have been identified as having potential forboth tidal and wave powered developments [7,8], and this offersan opportunity for an additional marine industry. There is a needto ensure that the growth of this emergent industry considersexisting users and important environmental features, and there isa clear role for MSP to guide its spatial development. Spatial seause scenarios allow you to anticipate potential future opportu-nities, conflicts or compatibilities for the area that can guideproactive decision-making [1].

In a national review of pilot marine spatial plan projects carriedout in Scotland during 2006–2010, it was recognised that theremay be some reluctance to defining strict zones for differentactivities [9]. Whilst zoning has been hailed by some as a panaceafor comprehensive ocean management [10], others point out therequirement for assumptions on future requirements zoning isdependent on [11]. Developers of renewable devices felt that, at atime when the industry is fast evolving, there are many factors tobe considered, including the actual capacity/size of array devel-opment, type of technology, energy climate and extraction perfor-mance. There was the belief that in Shetland some previous effortsat zoning development areas were based on somewhat arbitraryor directly challengeable assumptions (e.g. cut off set on availableenergy climate or overall farm capacity). In spite of this, it wasacknowledged that without any clear spatial guidance on the typesof activities that may be able to co-exist in which areas, MSP isunable to provide direction or help in ‘streamlining the develop-ment application process’ [9]. Alternative suggestions includedzones that could be used to define areas by their character, existinguses and suitability for different activities, within which morespecific policies could apply. As a result, the industry felt that amore flexible and cumulative approach, that allows for re-analysisof the localisation of renewable energy with ‘fuzzy’ zones orpreferred areas without excluding any but the most restricted orsensitive sites, was considered to be the favoured option [12,13].

In response to these demands, a sensitivity led approach toidentifying suitable areas for renewable energy development wasdeemed suitable for inclusion in the SMSP. The result is therecently published Regional Locational Guidance for Wave andTidal Devices in the Shetland Islands (RLG), which uses ArcGISs tomap and integrate spatial data on development constraints apply-ing to renewable energy developments [14,15].

1.4. Regional Locational Guidance overview

The NAFC Marine Centre report “Regional Locational Guidancefor Wave and Tidal Energy in the Shetland Islands- May 2013” [15]is the culmination of several years' consultation and modellingwork. The process to develop appropriate constraint weighting fordifferent activities and features began in 2007, prior to thepublication of the first draft of the SMSP. The intention at thattime was to implement model results through policy; however,despite a Spatial Analysis Working Group (consisting of a subset ofthe overarching Steering Group) approving the use of the model,the overarching Steering Group did not approve publication. Thiswas due to a level of mistrust in the original model, borne fromassumptions that risked being misleading. Through fundamentalimprovements made to the methodology, the RLG was accepted toform part of the SMSP through policy in the fourth edition of theSMSP [4].

The spatial model created for the RLG shows potential areas oflowest conflict between existing uses and values and renewableenergy developments, both at sea and relating to cable landingsites. The model reflects a process of consultation on constraintswith local advisors, planners, regulators, community representa-tives, NGOs and developers (hereafter referred to as stakeholders),and incorporates environmental, social, cultural and economicconsiderations into the site selection process for marine renewableenergy. The model is designed as a decision support tool to assistin making more informed decisions about where developmentsare more likely to be successful and where they are not. The mapspresented do not illustrate clear boundaries between favourableand unfavourable areas for marine development, but representareas that warrant further, site-specific investigation.

2. Materials and methods

Marine biophysical features and maritime activities withinShetland's marine and coastal environment have been identified,and their spatial extent mapped, in the SMSP [4], with the dataavailable to download from http://www.nafc.ac.uk/SMSP.aspx.Data within the SMSP were collected through a variety of meansand data sources, and are detailed in Tables 1 and 2. The spatialextent of each of these features and activities (hereafter referred toas features) has been subject to local consultation, producing bothlocal datasets and locally amended national datasets. These featuredatasets thus have a degree of local ‘quality control’, or verifica-tion, increasing confidence in the datasets and subsequent modeloutputs. Some of the datasets also include a measure of feature‘intensity’, for example, levels of demersal fishing effort, or birdand animal population distributions.

This RLG model makes use of the SMSP data in order to modelspatially varying ‘total constraint levels’ on renewable energydevelopments (hereafter referred to as developments), in particu-lar, tidal and wave powered devices. The model was developed inArcMaps 10.0, using the spatial analysis toolbox. The RLG wasseparated into two distinct sub-models, one focusing on con-straints to developments at sea, and the other focusing onconstraints to cable landing sites at the coast. It was decided thatconstraints relating to the technology (e.g. distance to land,hydrography, sediment type) were outside the scope of this model,as constraints are heavily device dependant and are subject tochange in a quickly evolving industry.

Initial consultation with local stakeholders and marine renew-ables companies provided details of features which would poten-tially be adversely affected by developments. Commercialstakeholders included representatives from marine renewableenergy companies (both wave and tidal), an electrical distributioncompany, fishing and aquaculture representatives, port authori-ties, and the United Kingdom Crown Estate. Local and nationalgovernment agencies, non-governmental organisations (such ascharities and sporting groups) and research institutes were alsoconsulted.

Each of the features identified by the stakeholders became a‘constraint layer’ within the spatial model (Tables 1 and 2). Thusthe model considers only features that may be negativelyimpacted by marine renewables developments. Individual featuresthen underwent further consultation with relevant stakeholders,in order to establish the level and spatial extent of the constraintthey represent. In general, constraint values ranged from 1 to 0, sothe maximum possible constraint was valued at 1 and no con-straint at 0. The exceptions to this were areas of ‘exclusion’constraints (assigned a value of 4), and some areas designatedfor nature conservation, which were valued higher (at 2) due totheir legally protected status.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–66 55

Constraint levels for each feature could be designated in twoways. A defined constraint level was applied where a feature hadbeen given a set constraint value. For example, national and inter-national nature conservation designated areas (such as Special Areasof Conservation (SAC), Special Protected Areas (SPA) and Sites ofSpecial Scientific Interest (SSSI)) had a set constraint level withintheir border, and no constraint outside their border. Defined con-straint levels were used to define ‘exclusion’ (very high constraint)zones, where, in the past, exclusion distances from a feature havebeen set through legislation or precedence of past consentingdecisions. For example, pipelines have an exclusion buffer of 230 meither side based on local consenting precedent. The use of a definedconstraint level or ‘exclusion buffer’ around the appropriate featuresensured these features were always of very high constraint. Definedconstraint levels were also used to map features where no intensitydata was available, such as for recreation. The constraint valueapplied to an area of defined constraint was dependant on theconstraint feature (Tables 1 and 2).

The other method of attributing constraint level was a spatiallyvarying constraint level, where a feature generated a continuousrange of constraint, from high to low. Fuzzy logic (a known toolused in GIS to rescale and compare disparate features) was used torescale the constraint range from 0 (where the constraint is notconsidered be an issue) to 1 (maximum constraint). This type ofconstraint was used to reflect distance from an important feature,for example, the further the distance from a bird colony, the lowerthe constraint. This scoring method was also used for featureswhich were spatially continuous but vary in intensity, such asvarying levels of fishing activity (Tables 1 and 2), where the samegraduated scoring (i.e. 0–1) was applied, but instead of beinglinearly related to distance, this constraint level was matched to acorresponding level of feature intensity.

Spatially varying constraint layers were created for all con-straints in each sub-model, and mapped. The model layers, basedon individual feature types, were then summed within the sea andcoast sub-models, with equal weighting to each layer, to create the

Table 1Constraints at sea. Data used to model constraints at sea, with designated assigned scoring. In addition to the constraint consultees, the model was consulted upon by theShetland Islands' Marine Spatial Plan Advisory Group.

Constraint Data source Dataavailablefrom

Constraint type Constraint level Constraint consultee

Aquaculture (Fin Fish) SiteShetland Islands Council SMSP Exclusion – 250 m 4 Shetland Island CouncilDefined-250–500 m 1 Representatives of Aquaculture

IndustryVarying – 500–1000 m 1–0Aquaculture (Shellfish &Algae) Site

Shetland Islands Council SMSP Exclusion – 250 m 4 Shetland Island CouncilRepresentatives of AquacultureIndustry

Varying – 250–1000 m 1–0

Cables KIS-CA; Shetland Islands Council SMSP Exclusion – 250 m 4 Subsea Cables UK(2012) GuidelinesCetaceans Shetland Amenity Trust SMSP Defined – 300 m 1 Scottish Natural Heritage;

Varying – 1000 m 1–0 Shetland Biological Records Centrea

Demersal Fishing Marine Scotland SMSP Varying – intensity based 1–0 Shetland Fishermen's AssociationDredge and DisposalGrounds

Lerwick Port Authority;Natural Capital; UKHO

SMSP;UKHO

Exclusion – extent 4 Lerwick Port Authority; ShetlandIslands Council

Important Species andHabitats (PMFs)

Various SMSP Defined – extent 1, cumulative Scottish Natural Heritage

Local Policy DevelopmentRestrictions

Shetland Islands Council; Lerwick PortAuthority; Broonies Taing Pier Trust

SMSP Defined – extent 1 NA

National Scenic Areas &Local Landscape Areas

Scottish Government; Shetland IslandsCouncil

SMSP; SIC Defined – extent 1 Legislation

Nature ConservationDesignated Areas

Scottish Natural Heritage; RSPB;Shetland Islands Council

SMSP;RSPB

Defined – SAC, cSAC & SPA2, cumulative LegislationDefined – SSSI, RAMSAR,LNCS, NNR & RSPB

1

Otters Shetland Amenity Trust SMSP Defined – 400 m 1 Shetland Biological Records Centrea

Varying – 400–500 m, to10 m depth contour

1–0

Pipelines Shetland Islands Council SMSP Exclusion – 230 m 4 Shetland Islands CouncilRecreational Use NAFC Marine Centre SMSP Defined – extent 0.5, cumulative

(maximum 1)NA

Seabirds Shetland Amenity Trust SMSP Defined – 100 m 1–0 Shetland Biological Records Centrea;SOTEAG

Varying – 100–1000 mSeals- Protected Scottish Government SMSP Defined – extent 1 Scottish Natural Heritage

Haul-outs Varying – 0–500 m 1–0Nursing & Scottish Natural Heritage; SMSP Defined – extent 0.5Pupping Areas Sea Mammal Research Unit Varying – 0–500 m 0.5–0Density at sea Scottish Government Varying – Intensity based 1–0

Shellfish Fishing Interviews with local fishermen; ShetlandShellfish Management Organisation

SMSP Varying – economiccontribution based

1–0 Shetland Shellfish ManagementOrganisation

Shipping Routes Maritime and Coastguard Agency;Shetland Islands Council

SMSP Exclusion – 250 m 4 Maritime and Coastguard Agency

Waste-Water Discharge &Water Abstraction

Scottish EnvironmentProtection Agency

SMSP Varying – 100 m 1–0 SEPA Environmental QualityStandards

Wrecks & Historic MarineProtected Areas

Shetland Amenity Trust; RCAHMS;Historic Scotland

SMSP;RCAHMS;

Defined – HMPA 2 LegislationVarying – 1000 m 1–0 Shetland Regional Archaeologista

a Part of Shetland Amenity Trust.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–6656

full model output. Model resilience was assessed by doubling theweighting of each of four constraint layers (for each of the sea andcoastal sub-models; Table 3) in the final summation step of themodel, and comparing the results to the equal weighting modeloutput.

The RLG is linked to a policy within the SMSP, which isdesigned to guide developments away from areas of higherconstraint, towards areas of lower constraint. In order to assist inease of interpretation of the model results by developers anddecision makers, constraint levels were assigned into 4 ‘levels’(LOW, MEDIUM, HIGH, and VERY HIGH). Stakeholders felt acontinuous spectrum of constraints were difficult to interpret,and distinct ‘levels’ were visually clearer, particularly with valuesclose to the boundary between LOW and MEDIUM (at which thenecessity for mitigation measures, as per the SMSP policy, istriggered).

The boundaries between LOW, MEDIUM, HIGH and VERY HIGHconstraint levels were carefully considered and subject to con-sultation. A designation of MEDIUM constraint level leads to arequirement for mitigation measures, as per the SMSP policy, andso a constraint level designation of MEDIUM, or above, offers alevel of protection to an area or feature. Thus, the constraint valueat which features attain MEDIUM constraint was especially impor-tant. A constraint value of 0.75 was considered appropriate as theminimum value of the MEDIUM constraint level. A value of 0.75 or

above within a constraint layer (i.e. for an individual feature type)can correspond to a relatively high ‘intensity’ of a feature (e.g. ofdemersal fishing effort), or the presence of an important, uniquefeature (e.g. a Priority Marine Feature, PMF). Multiple features ofrelatively low intensity or importance (i.e. individually of con-straint values less than 0.75, LOW constraint level) can becomeprotected by summation, through ‘cumulative importance’. Thisprovides a measure of protection when multiple lower constraintfeatures have a reliance on an area.

The delineation between MEDIUM, HIGH and VERY HIGH wasof less critical importance, as all are considered equally in thepolicy (all require mitigation). However, the further splitting ofconstraint values above 0.75 was agreed by stakeholders, as afurther visual indication of the level of conflict a development waslikely to encounter. As such, the HIGH constraint level wasassigned at a total constraint level of 2–4. Thus some areasdesignated for nature conservation, such as SAC and SPA, whichhad been assigned a constraint value of 2, consequentially becomeof HIGH constraint, even before the addition of any constraint dueto overlying features. This was considered realistic in terms oftheir legal protection. A constraint level of VERY HIGH wasassigned to constraint values of 4 or higher. This meant thatindividual features requiring exclusion levels of constraint, due tolegal requirements or planning precedent, were assigned a con-straint value of 4 (such as pipeline and cable exclusion buffers),

Table 2Constraints at the coast. Data used to model constraints at the coast, with assigned constraint scoring. In addition to the constraint consultees, the model was consulted uponby the Shetland Islands' Marine Spatial Plan Advisory Group.

Constraint Data source Availablefrom

Constraint type Constraint scoring Constraint consultee

Archaeology Shetland Amenity Trust SMSP Varying – 500 m 1–0 Shetland RegionalArchaeologista

National Scenic Areas & LocalLandscape Areas

Scottish Government; ShetlandIslands Council

SMSP; SIC Defined – extent 1 Legislation

Nature Conservation DesignatedAreas

Scottish Natural Heritage; RSPB SMSP;RSPB

Defined – SAC & SPA 2 Legislation

Defined – SSSI, RAMSAR, NNR,LNCS & RSPB

1

Otters Shetland Amenity Trust SMSP Defined – 400 m 1 Shetland Biological RecordsCentrea

Varying – 400–500 m 1–0Recreational Use Various; NAFC Marine Centre SMSP Defined – extent 0.5, cumulative

(maximum 1)NA

Seabird colonies JNCC SMSP;JNCC

Defined – 100 m 1 Shetland Biological RecordsCentrea; SOTEAG

Varying – 100–1000 m 1–0Seals- Protected Scottish Government SMSP Defined – extent 1 Scottish Natural Heritage

Haul-outs Varying – 0–500 m 1–0Nursing & Scottish Natural Heritage; SMSP Defined – extent 0.5Pupping Areas Sea Mammal Research Unit Varying – 0–500 m 0.5–0

Wildness Scottish Natural Heritage SMSP Varying 1–0 NA

a Part of Shetland Amenity Trust.

Table 3Testing model resiliency. Individual constraint layers were doubled in weighting within the final model summation. The distribution of the constraint levels of the modeloutputs were compared statistically, using ANOVA, and not found to be significantly different between iterations (p40.05, fo fcrit).

Weighting Total constraints at sea Total constraints at coast

min max mean st. dev. Sig diffn Min max mean St. dev. Sig diff*

Equal weighting 0.0121 16.3431 1.1506 1.5438 – 0 8.4053 2.6679 1.1637 –

Archaeology layer weighting doubled – – – – – 0 9.4050 3.1882 1.3413 noDemersal fishing effort weighting doubled 0.0129 16.6562 1.4621 1.6660 no – – – – –

Nature conservation designated areas weighting doubled 0.0121 18.3431 1.2794 1.7719 no 0 12.4053 2.9300 1.7715 noRecreation weighting doubled 0.0121 16.3431 1.1597 1.5634 no 0 8.4063 2.6714 1.1671 noSeals weighting doubled 0.0240 17.3431 1.3227 1.6287 no 0 8.6230 2.8047 1.2326 no

n ANOVA, p40.05, fo fcrit.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–66 57

Fig. 2. Examples of constraints layers within the ‘constraints at sea’ sub-model, zoomed in for detail on the box shown in (a) Map of Shetland Islands and 12 nautical mile limit.(b) Aquaculture constraint layer (socio-economic constraint), with ‘exclusion’ zone of constraint¼4 over licensed site and to a distance of 250 m from site (based on localprecedent), and constraint decreasing thereafter until constraint¼0 at one km distance from the site licence area. (c) Recreation constraint layer (cultural constraint), wheredefined areas of recreational activities are of constrain¼0.5, with a maximum of 1 where multiple activities take place. (d) Breeding seabirds constraint layer, where a definedconstraint of 1 was applied up to 100 m from the colony, and then decreased with distance until constrain¼1 at one km distance from the colony (based on consultation). Mapsnot to be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and database rights.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–6658

and were automatically of VERY HIGH constraint, and areas withmultiple features could also be classed as VERY HIGH.

3. Results

Model outputs were mapped, for individual constraint layers(Fig. 2) and the sub-models' total constraints, showing totalconstraint both at sea (Fig. 3) and at the coast (Fig. 4). Visualassessment by stakeholders of the final model output confirmedthe results were realistic, e.g. areas with explicit, spatially specificlegal protection were of higher constraint than areas without, andno one feature was disproportionally represented.

Constraints were then grouped into four ‘levels’ (Figs. 5 and 6):LOW (total constraint o0.75), MEDIUM (0.75r total constraint o2),HIGH (2r total constraint o4), and VERY HIGH (total constraintZ4). The percentage of total area designated to each constraint levelwas calculated (Table 4). Over 50% (6431 km2) of sea area was

designated as LOW constraint, with less than 10% (1140 km2) VERYHIGH (exclusion constraint level). In comparison, only 2% (5.2 km2) ofcoastal land was considered LOW constraint, though the coast had asimilar proportion of VERY HIGH constraint as the sea (11.39%,28.9 km2).

The doubled weighting model outputs (Figs. 7 and 8) werecompared to the results to the equal weighting model output(Figs. 5 and 6) to assess model output resilience. The statisticaldistributions of total constraint levels within the model results werenot significantly different between models (Table 3). The percentageof model grid cells at LOW, MEDIUM, HIGH and VERY HIGHconstraint levels were also compared between model iterations.The model outputs were not found to markedly alter, particularlyat lower constraint levels (a maximum of 7.3% decrease in total areaclassed as low constraint). However, visual inspection of these modeliterations showed they provided unrealistic results, seen particularlyclearly with doubled constraints in nature conservation designatedareas (Fig. 7b), where large areas became excessively highly

Fig. 3. Total constraints on wave and tidal marine renewable energy developments at sea, calculated as a summed total of all constraint layers. Maps not to be used fornavigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and database rights.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–66 59

constrained, particularly within the SAC and SPA areas; areas whichhad already been assigned as HIGH constraint level. Therefore, theequal weighting model was found to be robust and realistic and wasused in the final RLG output.

4. Discussion

Future planning of the marine environment should includespatial sea use scenarios to help determine the desired direction ofdevelopment for any management area, and in selecting manage-ment measures needed to get there [1]. Decision support tools,such as GIS, are useful aids in planning future spatial and temporaluses of the marine environment [16]. The RLG presents spatialpotential, and is adaptable to expansion in the future as new andmore comprehensive data become available. For industry, the

RLG provides clear guidance on areas suitable for further site-specific investigation on commercial and economic viability. Theadaptability of the model also ensures the methodology is appro-priate for use in modelling constraints applying to other indus-tries. A version of the model has been developed for use inaquaculture site selection in England [17], demonstrating theflexibility of the model for other industries.

It is recognised that the output of this model is only as good asthe input data, and significant data gaps and limitations wereidentified during the course of this study. For example, the dataused for breeding birds is somewhat out of date (having beengathered in 2000). There are coverage issues within data for otherenvironmental features. Spawning and nursery grounds of com-mercial stocks are not mapped. A combination of VMS, interviewand GPS plotter data was used for fishing effort, but gaps still existin data covering socio-economic dependency on fishing grounds.

Fig. 4. Total constraints on wave and tidal marine renewable energy development cable landings on the coast, calculated as a summed total of all constraint layers. Maps notto be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and database rights.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–6660

Incomplete knowledge of the spatial distribution of marine fea-tures should not stop the implementation of MSP; rather, furtherdata collection forms part of the iterative process of MSP [1]. Thelimitations of the data within the RLG highlight where data gapscould be filled with primary research, and site specific informationwill be gathered over time and used in future iterations of themodel. The key value of the model is that it is designed toaccommodate change as new data and information becomesavailable.

One of the challenges in ecosystems based management andMSP is finding a way to incorporate and compare physical, eco-nomic, environmental, social and cultural activities and features.Reclassifying all features on the same constraint scale allows forincorporation of all types of features into one model. This provides ameasure of social justice, where local cultural and socio-economicfeatures are considered alongside nationally valued features. This

equality could only be achieved by working closely with stake-holders to ensure buy-in to the model development.

Many datasets included in the model could only be includedthrough explicit data sharing from stakeholders. The ownership ofseveral datasets within the model rests with the data provider or‘knowledge holder’. It was important to many of these knowledgeholders that their individual contribution to the model wasdisplayed in a way acceptable to them, and that the ‘raw’ datawas not available to all. The final step in the model, the summationof constraints, ‘masks’ the individual constraint layers within thefinal model output, thus ensuring confidentiality of their data.

Recommendations have been made to develop models such asthis as a web-based GIS tool in order to maximise accessibility [17],allowing stakeholders to undertake their own scenario testing.Although this would add greater depth of transparency to themarine planning process, confidentiality issues associated with

Fig. 5. Constraint levels on wave and tidal marine renewable energy developments at sea. The total summed constraint values from all layers in the at sea constraints sub-model have been grouped into LOW (total constraint r0.75), MEDIUM (0.75o total constraint o2), HIGH (2r total constraint o4), and VERY HIGH (total constraint Z4).This grouping was done at the request of stakeholders, after consultation revealed the grouped results were easier to interpret by users of the RLG. Maps not to be used fornavigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and database rights.

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certain data will create problems, and may result in under-representation of a sector within features included in any web-based tool, with consequential bias introduced to output ofthe tool.

A range of economic, social and cultural features were con-sidered within the RLG model, with the scoring of individualfeatures based on the requirement to reflect realistic levels ofprotection and spatial dependency. Features with high statutoryprotection were given a higher scoring than features with lower

protection. Highly protected features tend to be unique and/ orspatial explicit, for example, exclusion buffers around electricalcables (scored as 4 in the model) and SAC and SPA (scored as 2), ascompared to areas with a high intensity of demersal fishingactivity (scored as 1), or an area with recreational activity (scoredas 0.5 for each activity, to a maximum of 1). This scoring is due inpart to the consideration given during the application process towhether features in conflict with a proposed development couldadapt (behaviourally or spatially) to the development. Those

Fig. 6. Constraint levels on wave and tidal marine renewable energy development cable landings on the coast. The total summed constraint values from all layers in thecoastal constraints sub-model have been grouped into LOW (total constraint r0.75), MEDIUM (0.75o total constraint o2), HIGH (2r total constraint o4), and VERY HIGH(total constraint Z4). This grouping was done at the request of stakeholders, after consultation revealed the grouped results were easier to interpret by users of the RLG.Maps not to be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and database rights.

Table 4Percentage of total area (and area in km2) at each constraint level, for both the constraints at sea and constraints at the coast sub–models.

LOW MEDIUM HIGH VERY HIGH Total area

Constraint at sea 52.29% (6431 km2) 29.77% (3662 km2) 8.68% (1068 km2) 9.26% (1140 km2) 12,301 km2

Constraint at coast 2.06% (5.2 km2) 26.14% (66.3 km2) 60.42% (153.5 km2) 11.39% (28.9 km2) 253.9 km2

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Fig. 7. Constraint levels on wave and tidal marine renewable energy developments at sea, with weighting doubled for (a) demersal fishing effort, (b) nature conservationdesignated areas, (c) recreation, and (d) seal densities. Maps not to be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011).Contains UKHO data© Crown copyright and database rights.

J.F. Tweddle et al. / Marine Policy 50 (2014) 53–66 63

Fig. 8. Maps not to be used for navigation. Contains Ordnance Survey data© Crown copyright and database right (2011). Contains UKHO data© Crown copyright and databaserights.

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features which can adapt are considered less of a constraint thatthose features which cannot.

The RLG linked policy within the SMSP is worded such thatareas of MEDIUM and above constraint level are defined by themapped model output, and not by explicitly stated spatial bound-aries (zones) within the policy. This provides a measure ofadaptability not available to ‘zoned’ plans, that if new data becomeavailable, or if perception of the constraint levied by a featureshifts, the model can be re-run, and the new model outputmapped and implemented quickly, without changing the policy.Indeed, it is stated in the SMSP policy that the model will be re-evaluated every six months. Thus, the RLG adapts GIS into policy ina way that is flexible to spatial changes and temporally changingvalues, and without requiring fixed spatial boundaries to bedefined, e.g. through zoning. This avoids one of the potentialpitfalls of zoning, of the zones becoming outdated. The lack ofzoning also encourages co-location of activities [11]. MSP is acontinuous activity [1], and guidance such as this RLG is anexample of adaptive management which responds to changingconditions.

The spatial distribution of each constraint level at sea is nothomogenous or random, with highest constraint levels tending tobe close to the coasts, with most areas of LOW constraint levelbeyond 1 nautical mile from land. Economic, social and culturaluse of the marine environment is often limited to near-shore, dueto ease of access, and costs and technical constraints associatedwith accessing resources further offshore, thus increasing con-straint levels near land. However, some caution must be used ininterpreting feature, and hence constraint, distributions, in parti-cular with regard to ecological features. The majority of evidence isconcentrated close to land, in part due to the technical andmonetary constraints of surveying further offshore. This createsincreased constraint levels close to shore, and potentially creates afalse LOW constraint further offshore. Thus, areas with LOWconstraint level are not necessarily without conflicting features,and an impact assessment would still be required to assess thecompatibility of any new developments with existing features.

Protection efforts vary between species and habitats, with abias towards those occurring in shallower water. This may be ahistoric legacy due to the ease of sampling, and greater knowledge,of shallower waters. As this model considers protected species andhabitats under the constraint layer ‘Important Species and Habi-tats’, any bias in the designation process will be reproduced as biasin the final constraint model. However, this bias is also reproducedin the development consenting process, and thus is a validconstraint on development.

Coastal land is more highly constrained than the sea area; withonly 2.06% of coastal land area designated LOW constraint(Table 4). However, this does not mean no land is available forcable landings, just that mitigation measure will need to beenacted. 11.39% of land area is designated VERY HIGH constraintlevel, and could be considered as ‘exclusion zones’, leaving almost90% (�225 km2) of land area as open for consideration. Theheavier constraint levels placed on coastal land are due, in part,to increased knowledge of the existence and location of landfeatures and uses, compared to those occurring in the sea.

That the RLG model considers both constraints at sea and thecoast makes it an example of integrated coastal zone management,with constraints associated with the placement of the device atsea and cable landings on land integrated into one guidancedocument. This assimilation allows for better, more integrateddecisions to be made by planning authorities [1].

The Scottish Government has produced national level SectoralMarine Plans [18–20] for wave, tidal and offshore wind marinerenewables, which are currently undergoing consultation. Thesenational Sectoral Plans are designed to guide strategic decisions by

the Scottish Government on identifying areas suitable for devel-opment by the renewables industry, just as the RLG is designed toguide at a local level. The important differences between themodels used in the Sectoral Plans and the RLG lie in the data usedand the weighting applied. This RLG incorporates both local andlocally verified national datasets, and thus contains a moreexhaustive list of features in the region which are of localimportance, some of which are either not available or are notvalued nationally. Thus, the RLG model input data has a finergranulation than the national model, with increased confidence inthe data, than would be obtainable if only incorporating nationaldata sets. Although no confidence assessment has been carried onthe Scottish Government's input data, a rigorous confidenceassessment has been undertaken on the data held within theSMSP, with an overall rating of 80% for data used within this model[21].

The national Sectoral Plans' models include data on renewableenergy resources (tidal current velocities and wave power densi-ties), and data such as bathymetry and sediment type, relevant totechnical considerations. The RLG does not include this data, as itwas considered that these type of constraints were device depen-dant and are subject to change as technology develops. The outputof the Sectoral Plans is heavily influenced by resource availability,and the final ‘zones’ recommended as suitable for developmenthighlight where resources are suitable, and few features ofnational or international features are present.

Another fundamental difference between the local RLG andnational Sectoral Marine Plans is in the constraint scoring of thefeatures, with scoring within the RLG reflecting local communityvalues, societal interests and planning precedents, differentiatingthe methodologies between national and regional models. Stake-holder engagement has been key to the development of thisguidance, and has been identified as crucial to the marine spatialplanning process in Shetland [12]. This has enabled the RLG outputto be directly linked to policy whilst the national Sectoral Planshave not.

These differences in model methodology (data used andweighting applied), in combination with the ‘zoning’ output usedin the national Sectoral Plans, have resulted in some divergencebetween regional and national recommendations. The zonerecommended for wave based developments in Shetland's waters(Figs. 5 and 6) is classified by the RLG as LOW constraint in 49% ofits area, and VERY HIGH in 10%. Thus, mitigation measures wouldbe required of any development in over half the area, and 10% ofthe area is would require significant planning and mitigation dueto current features requiring ‘exclusion’ buffers. Of the SectoralPlan's three zones for tidal energy, an average of 12% of the zonedarea is classified in the RLG as LOW constraint, with 0% LOWconstraint in one particular zone. Thus, mitigation measures arelikely to be required for any development. The zones also havehigh percentages of area classed as ‘VERY HIGH’ constraint (11–50%), further constraining the area suitable for development.

The differences between national and regional Plans are,however, reconcilable. The Sectoral Plans guide developerstowards regions with resources suitable for potential for develop-ment (large zones within the Shetland Islands in this case), andthe RLG provides higher resolution spatial guidance on sitesuitability. This offers an example of a nested, hierarchicalapproach, which provides an optimal approach to MSP [22,23]-higher level plans, in this case national, providing context for locallevel plans, and local level plans supporting the strategic prioritiesof higher level plans. Additionally, both the RLG and the nationalSectoral Plans require further site-specific surveying of areasproposed for development. Overall, zoning is useful as a strategictool, but is found to be too prescriptive and narrow at thelocal level.

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5. Conclusions

High levels of stakeholder engagement and local representationhave underpinned this RLG, and its parent SMSP, allowing thecapture of as large a spectrum of potential constraints to renewabledevelopments as is currently possible. The mechanism of the modelallows incorporation of data from all stakeholders in an equivalentand transparent way, to produce a single constraint model based onsocietal and cultural values. This unique method of valuing activitiesand features for consideration is a far cry away from the traditionalapproach of weighting monetary values and equivalences againstone another. The structure of the policy allows integration of GIS datainto the policy without the need to fix spatial boundaries or create‘zones’. This allows for updating of the GIS based constraint mapswithout changing the policy or redefining zones; for example, if newdata becomes available, regulations change, or if social or culturalvalues shift. The model has been adapted and used for differentdevelopment types by national government, proving its adaptabilityand robustness. The RLG will help support marine planners anddevelopers by providing a rapid way to identify areas requiring sitespecific investigation.

Shetland's marine environment is of high economic impor-tance, and marine renewables offer an opportunity for an addi-tional marine industry. However, there is a need to ensure that thegrowth of this emergent industry considers existing uses of themarine environment, and ecological considerations. Marine spatialplanning can provide guidance to future developments by mana-ging the environment effectively. UNESCO [24] states MSP should“establish a more rational use of marine space and the interactionbetween its uses, to balance the demands for development withthe need to protect the environment, and to achieve social andeconomic objectives in an open and planned way.” This RLG,sitting within the overarching SMSP, fulfils these objectives.

Acknowledgements

We would like to thank Marine Scotland for providing financialsupport for this project. We also wish to acknowledge the timeand efforts of the SMSP Advisory Group, and the stakeholdersinvolved in this work.

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