How does EMF from submerged cables impact fisheries?
Electromagnetic fields (EMF) occur anywhere electricity is used and are also naturally produced by the earth’s magnetic field. For an offshore wind farm EMF is generated by the electricity passing through the subsea cables. EMFs from the electricity grid are non-ionising. This term means that they do not have enough energy to cause damage to human or fish cells in the same way ionising radiation does. Forty years of research has found no hazardous effects from long-term exposure to low levels of EMFs.
Some marine organisms use natural magnetic fields for navigation, while many elasmobranchs (sharks, skates and rays) use their sensitivity to electrical fields to help in the detection of food. This makes it important to investigate whether EMF from the cables used in wind farms has any effect on fish and to ensure the appropriate steps are taken to avoid or mitigate the impact of EMF on marine life.
Studies carried out on cables show that when they are buried to a depth of 1 metre the magnetic field at the seabed is actually less than the earth’s own natural magnetic field.* Wind farm developers will try to bury all cables up to two metres below the seabed wherever possible. Research carried out in Scotland found that while salmon, sea trout and eels can detect magnetic fields, since the field from the cables will be below that of the earth’s magnetic field it is unlikely they would even detect it.** Studies on electrical fields suggest that any impact on fishing is very localised and restricted to approximately 30 metres from the cable.***
* MORL (2012) Telford, Stevenson, MacColl Wind Farms and associated Transmission Infrastructure Environmental Statement, Technical Appendix 4.3 D – Electromagnetic Fields Modelling. Technical report produced by TNEI Services Ltd. For Moray Offshore Renewables Ltd.
** Gill and Bartlett (2010). Literature review on the potential effects of electromagnetic fields and subsea noise from marine renewable energy developments on Atlantic salmon, sea trout and European eel. Gill, A. and Bartlett, M 2010. Scottish Natural Heritage, Commissioned Report No. 401.
*** Collins, N. 2012. Assessment of Potential Ecosystem Effects from Electromagnetic Fields (EMF) Associated with Subsea Power Cables and TISEC Devices in Minas Channel. Prepared by CEF Consultants Ltd. for Fundy Ocean Resource Centre for Energy (FORCE), Halifax, NS, 39p.