Marine Scotland

Effects of magnetic fields on the behaviour of eels and salmon

September 10, 2015 by No Comments | Category Marine Scotland general, Marine Scotland Science, Scottish Marine and Freshwater Science report series

Two new reports on the potential effects of magnetic fields (MFs) associated with marine renewable energy developments (MREDs) on the behaviour of Atlantic salmon and European eels have been published in Scottish Marine and Freshwater Science.

Industrial developments in coastal waters, particularly for harnessing marine renewable energy, require deployment of electricity cables, which generate electromagnetic fields (EMFs). Atlantic salmon probably have a magnetic sense used to aid migrations. This raises the question of whether Atlantic salmon detect and respond to EMFs generated around cables.

Effects of mains frequency (50Hz) magnetic fields (MF) on behaviour of captive Atlantic salmon were examined in a large arena. Fish swam spontaneously within the arena passing from one side to the other through Helmholtz coils (arranged in four pairs) that penetrated a net barrier. When activated, a uniform intensity MF was generated between coils within a pair.

Large salmon (62-85cm) showed no significant response to the field in terms of alarm, avoidance, accelerated or decelerated swimming. Furthermore, there was no evidence that the numbers of smaller post-smolts (24-41cm) passing through the coils was affected by MF.

It has been reported previously that passage of European eels in the wild was delayed due to a power cable. Efforts were made to examine the behavioural basis for such delay in the laboratory arena. Few of the eel specimens exhibited sustained swimming and for those that did there was no evidence of a response to the generated MF. Further work is required using higher intensities of MF and night time observations of eels to explore the issue further.

Full reports are available at:

Volume 6, Number 8: Effects of AC magnetic fields (MFs) on swimming activity in European eels Anguilla anguilla

Volume 6, Number 9: Behavioural responses of Atlantic salmon to mains frequency magnetic fields

For any enquiries relating to these reports, please contact Ross Gardiner at: ross.gardiner@gov.scot


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