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