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Marine renewables in the North of Scotland: using a hydrodynamic model to examine risks
to migratory fish
6th World Fisheries CongressEdinburgh, 10th May 2012
Andrew Guerin and Peter Bowyer
Environmental Research InstituteCentre for Energy and the Environment
Thurso
Outline
BackgroundModelling studyResults so farConclusionsLimitations and future work
Background
Scottish Government target: “to meet an equivalent of 100% demand for electricity from
renewable energy by 2020”2020 Routemap for Renewable Energy in Scotland
http://www.scotland.gov.uk/Publications/2011/08/04110353/0
Marine Renewables
Technologies:• Offshore wind• Wave power• Tidal stream power
New Industry: varied approaches (especially for wave)Environmental implications are uncertain:
• Impacts on seabirds• Impacts on marine mammals• Impacts on benthic habitats• Impacts on regional biodiversity• Impacts on fish, including migratory fish
Atlantic Salmon, Salmo salar
Anadromous fish• Hatch in freshwater, resident for 1-3 years• Migrate to marine feeding grounds in the North
Atlantic for 1-5 years• Return to natal rivers to spawn
Under threat from anthropogenic impacts• Pollution of freshwater habitats• Hydropower (rivers) and dams • Marine fisheries • Climate change
Atlantic Salmon, Salmo salar
Anadromous fish• Hatch in freshwater, resident for 1-3 years• Migrate to marine feeding grounds in the North
Atlantic for 1-5 years• Return to natal rivers to spawn
Under threat from anthropogenic impacts• Pollution of freshwater habitats• Hydropower (rivers) and dams • Marine fisheries• Climate change
Returning fish numbers and condition are declining
Atlantic Salmon and Marine Renewables – a potential new threat?
Atlantic Salmon and Marine Renewables – a potential new threat?
Noise impact (construction and operation)
DRRRRRR
DRRRRRR
DRRRRRR
Atlantic Salmon and Marine Renewables – a potential new threat?
Interference with navigation (electromagnetic emissions)
??
?
Atlantic Salmon and Marine Renewables – a potential new threat?
Direct interactions (bladestrike and entanglement)
Pentland Firth and Orkney Waters
Source: www.thecrownestate.co.uk
Pentland Firth and Orkney Waters
Source: Malcolm, I.A., Godfrey, J. & Youngson, A.F. (2010)
Understanding the risks to adult S. salarpassing through the Pentland Firth
Understanding the risks to adult S. salarpassing through the Pentland Firth
Continental level
?
Understanding the risks to adult S. salarpassing through the Pentland Firth
Development area level
Pentland Firth
Orkney Islands
Mainland Scotland
BLUE: Wave energy sitesRED: tidal stream energy sites
Understanding the risks to adult S. salarpassing through the Pentland Firth
Device level
?
?
Understanding the risks to adult S. salarpassing through the Pentland Firth
Development area level
Pentland Firth
Orkney Islands
Mainland Scotland
BLUE: Wave energy sitesRED: tidal stream energy sites
Hydrodynamic Model
2D formulation of Princeton Ocean Model (POM)• Variable resolution (< 200m in Pentland Firth)• Boundary conditions from calibrated shelf model
Tracer particles released from 10km2 boxes at:• 58.65°N• 58.7°N• 58.75°N• 58.8°N• 58.85°N(all at 3.5°W)
Five particle ‘behaviours’• Passive• 0.1, 0.3 or 1ms-1 to the Southeast• 0.2ms-1 to the East
Model results
‘Fish’ deemed to have escaped Pentland Firth once they reached a pre-defined latitude (58.2°N) or longitude (2.5°W)
Model results
Example trajectories
Interactions with arrays
Four hypothetical tidal arrays corresponding to lease locations:• ARRAY 1: Inner Sound of Stroma• ARRAY 2: Cantick Head• ARRAY 3: Brough Ness• ARRAY 4: Ness of Duncansby
Simple linear fence (10 devices)
Interactions between devices andindividual particles recorded
Interactions with arrays
Interactions with arrays
Interactions with arrays
Interactions with arrays
Interactions with arrays
Interactions with arrays
Conclusions
1. Location of device arrays may influence their potential to impact migratory fish
2. Behaviour of migratory fish will also influence their risk of encountering device arrays (swimming speed, direction, and point of entry into tidal systems)
3. Demonstration of potential utility of modelling approach to assess relative impacts of future proposed arrays
4. Allied to approaches at other spatial scales, could improve understanding of overall impact of marine renewables
5. Approach not limited to returning Atlantic Salmon• Outmigrating smolts• Sea trout• Eels!
But….
Model limitations• 2-dimensional• Particular problem with coastal behaviour• Fixed vector swimming – oversimplification• Model doesn’t account for flow modification by arrays
Need data from the real world• Model validation• Swimming behaviour of S. salar in Scottish coastal waters
• Swimming speeds• Swimming depths• Swimming vectors• Responses to encountering coastline• Responses to tidal regime
Acknowledgements
Alan YoungsonAll ERI research and support staff – especially Matt Easton
ProjectsMarine Renewable Energy and the Environment (MaREE)Advancing Marine Renewable Energy research Capacity in Scotland (AMRECS) –
Strategic Research Development Grant
FundersScottish Funding CouncilHighlands and Islands EnterpriseEuropean Regional Development Fund
ReferencesMalcolm, I.A., Godfrey, J. & Youngson, A.F. (2010) Review of migratory routes and behaviour of Atlantic salmon, Sea trout and European eel in Scotland’s coastal environment: implications for the development of marine renewables. Scottish Marine and Freshwater Science, Volume 1 No 14. Marine Scotland-Science