Effect of anthropogenic electromagnetic fields used for subsurface oil and gas exploration (controlled-source electromagnetics, CSEM) on the fertilization success and embryonic development of Atlantic cod (Gadus morhua)

Surveys that rely on Controlled Source Electromagnetics (CSEM) explore the seabed for hydrocarbon deposits. These surveys can overlap temporally and spatially with spawning areas for Atlantic cod (Gadus morhua). Cod eggs are planktonic and develop in the water column and therefore may be exposed to the electromagnetic fields (EMFs) generated by CSEM. We replicated equivalent EMFs in the laboratory and tested their potential effects on cod reproduction. Two experiments were conducted: 1) 15-min. single EMF exposure of male cod, followed by assessment of sperm motility and subsequent monitoring of offspring development; 2) 15-min, single EMF exposure of fertilized eggs, followed by monitoring of embryonic development. Three EMF intensities, corresponding to 30 [50.3 μT], 100 [12.6 μT] and 1000 m [0.126 μT] between the organism and the source, were applied in each experiment. Exposure to EMFs had no effect on size, morphology or cardiac function in any of the experiments. Sperm velocities increased slightly, by 0.5 % in curvilinear path and 0.6 % in average path length post-exposure. However, the functional significance of this effect is likely negligible.