These Information Notes will support careful consideration of how, for a particular development, potential impacts that are considered low risk could be safely retired from further detailed consideration within Environmental Impact Assessments (EIA), where available evidence supports this approach. Ocean Energy Systems-Environmental (OES-Environmental) has set out a general process for risk retirement1,2 but for developments in Welsh waters, risk retirement should always be discussed between developers and Natural Resources Wales (NRW) at the pre-application stage. In the context of these Information Notes, risk retirement implies that all potential impacts are included for consideration at the project scoping stage, and that following a review of the evidence some impacts may be ‘scoped out’ of any further detailed assessment to focus EIA on key significant impacts3. In all cases, potential impacts should be acknowledged in EIAs, with evidence-based justifications describing why particular impacts could be ‘scoped out’ of further detailed assessment.
In a tidal stream array development multiple cables are used to carry power from devices to the shore or to subsea ‘hubs’ which are then connected to a single power export cable. The number and type of cables used will depend on the type and scale of the development. There are some concerns that mooring lines and cables could be a hazard for marine animals due to the possibility of entanglement. Entanglement is sometimes also referred to as entrapment, and in this Information Note is defined as an animal becoming caught in a system without possibility of escape (Garavelli 2020). Large cetaceans and basking sharks are thought to be most at risk from entanglement because of their behavioural traits and size (Benjamins et al. 2014). However, concerns about the possible risk to smaller marine mammals, diving seabirds and large fish have also been raised when considering the potential impacts of large arrays with multiple mooring systems and cables.