Name: Håkan Westerberg
Coded acoustic tags and an array with moored receivers were used to study the effect of a sub‐sea AC power cable on migrating European eel, Anguilla anguilla (L.) in the Baltic Sea. Sixty eels were tagged and the migration speed was measured in a strait with a 130 kV AC power cable. Observed swimming speed over the ground was corrected for advection by the water current. Eel swimming speed was significantly lower around the cable than both north and south of the cable. No details on the behaviour during passage over the cable were possible and possible physiological mechanisms explaining the phenomenon are unknown. Further work is needed to understand the nature of the effect.
Swedish Energy Agency
Strait separating Öland and Swedish mainland, Sweden
The purpose of this study was to investigate if effects of AC fields found by Poddubny (1967) and Poddubny et al. (1979) could be demonstrated. The experiment was carried out on migrating European eel, which is known to migrate in a fairly predictable, steady way in the Baltic Sea (Tesch, Westerberg & Karlsson 1991; Westerberg, Lagenfelt & Svedäng 2007).
The main conclusion from this experiment was a significant difference in swimming speed of migrating eels in the interval with an AC power cable, compared with the speed in the adjacent intervals of the array. It was not possible to find any alternative factor besides the presence of the cable that could explain the slower swimming speed. The observed decrease in speed in the middle interval at higher amperage in the cable was not statistically significant but was consistent with the hypothesis that an effect of the cable was related to the electromagnetic field.
From the point of view of environmental impact assessment, the effect of the cable on eel was small. There was no evidence that the cable was an obstruction to migration. Just two of the 60 eels turned back somewhere in the middle interval containing the cable and this can be explained by chance rather than caused by the cable.
Westerberg, H.; Langenfelt, I. (2008). Sub-Sea Power Cables And The Migration Behaviour Of The European Eel. Fisheries Management and Ecology, 15(5-6), 369-375.