Submarine power cables do not harm marine life

A new report from the Bureau of Ocean Energy Management (BOEM) addresses four questions about the impact of submerged power cables on fish and invertebrates, the principal one being whether electromagnetic fields (EMF) from underwater power cables attract or repulse fish or invertebrates.

The purpose of the study was to shed light on the potential effects of energized, seabed deployed, power cables on marine organisms, broadly applicable to planned and future renewable energy projects in the Pacific Outer Continental Shelf (OCS) region and other OCS planning areas. 

Researchers placed EMF meters on the sea floor along submerged power cables to collect data on fish and invertebrate behavior over three years.

The experimental design tested for the effect of inshore versus deep water cable placement. 

Researchers found that few biological effects could be detected from patterns of species relative abundance, and there was no evidence of behavioral response by electro-sensitive species. 

These findings may help inform appropriate mitigation measures for the permitting of undersea power cables.

Methodology: BOEM’s Pacific Region office and research partners from the University of California Santa Barbara undertook this experiment in a natural setting using existing, undersea power cables connected from three drilling platforms in the Southern California OCS–Platforms Heritage, Harmony, and Hondo, at depths to about 326 meters (1069 feet)–to Las Flores on the mainland. 

The cables run from the platforms toward the mainland to a seafloor depth of 10 meters (about 33 feet), buried inshore from there. 

All of these cables use the industry standards of the power cables that will be used for connecting devices (35 kilovolts) within renewable energy installations.

During the three-year study, researchers conducted 38 days of fish surveys, 30 days of invertebrate studies, and 38 days of plant studies–in February for the nearshore areas and October for the offshore areas. 

Overall habitats, they observed 4,671 individuals of a minimum of 44 species of fish. They also observed a total of 30,523 invertebrates from at least 43 invertebrate species.