The OES-Environmental 2020 State of the Science Report: Environmental Effects of Marine Renewable Energy Development Around the World builds on and serves as an update and a complement to the 2013 Final Report for Phase 1 of OES-Environmental and the 2016 State of the Science Report. Its content reflects the most current and pertinent published information about interactions of marine renewable energy (MRE) devices and associated infrastructure with the animals and habitats that make up the marine environment. It has been developed and reviewed by over 60 international experts and scientists from around the world as part of an ongoing effort supported by the OES collaboration that operates within the International Technology Cooperation Framework of the International Energy Agency (IEA).
The 2020 State of the Science Report consists of 14 chapters which can be downloaded as a whole or individually. Download Chapter 8: Encounters of Marine Animals with Marine Renewable Energy Device Mooring Systems and Subsea Cables here.
Most wave energy converters (WECs) and floating tidal turbines must be anchored to the seafloor and use mooring lines to maintain their position within the water column or on the water surface. MRE arrays may include transmission cables for device interconnection or to connect to offshore substations. The mooring lines and cables associated with MRE device mooring systems have the potential to entangle or entrap large marine animals. The likelihood of an encounter between marine animals and MRE cables is a function of the line/cable configuration and depth, as well as the animal’s size and behavior. The species considered to be at risk of encounters with MRE mooring systems and subsea cables are large migratory baleen whales because of their migratory patterns and feeding behaviors. These concerns are raised because of the entanglement of marine mammals with fishing gear and lines. However, MRE cables and lines do not have loose ends or sufficient slack to create an entangling loop.
There is a lack of empirical data and focused studies about entanglement risks associated with MRE device moorings and subsea cables. However, the relative spatial scales of the MRE devices and associated mooring components, water depth, and size of marine animals indicate a low likelihood of encounter and entrapment, because the mooring lines occupy a very small cross section of the water column.
The Short Science Summary for the chapter is available here.