Abstract
The rapid expansion of offshore wind farms plays a key role in meeting global Net Zero targets by 2050 and if delivered sustainably could address the dual challenges of climate change and biodiversity loss. Many countries are embracing ambitious approaches to environmental impact reduction by implementing concepts such as Biodiversity Net Gain, Nature Positive and No Net Loss. Such policies are now recognized in European and UK legislation, although generally only applicable to terrestrial activities. For the marine realm, there is little consensus on how Marine Net Gain can provide optimal environmental and societal outcomes from marine activities such as offshore wind farm construction, operation and decommissioning. This study sought to clarify the key issues that need to be addressed for effective implementation of Marine Net Gain. Following recruitment through a stakeholder mapping exercise, in-workshop and follow-up questionnaires sought to elicit expert opinions from multi-sector UK offshore wind farm stakeholders on a range of aspects of Marine Net Gain policy formulation and delivery. Over 80 % of participants indicated that certain external inputs, including information for climate change adaptation options and habitat mapping data, were important to enable delivery of Marine Net Gain. The most important ecosystem services to include within Net Gain measures were perceived as those relating to fisheries (mean 4.50, SD 0.51), maintaining nursery habitats (mean 4.41, SD 0.59), and climate regulation (mean 4.20, SD 1.). Stakeholders felt the most important Net Gain actions for environmental restoration/enhancement for future offshore wind deployment were shellfish/mussel bed (ave rank score 4.06) and invertebrate habitat restoration (ave rank score 4.60), and actions supporting plankton communities (ave rank score 4.67). Stakeholders agreed (83 %) that Net Gain actions should be considered at the decommissioning stage, and the preferred decommissioning option was the complete removal or abandonment of all structures. Stakeholders felt that strategic Net Gain assessments should prioritize fishing pressures (dredging: mean 4.27, SD 1.03; line and net: mean 4.21, SD 0.89) and those arising from physical structures (mean 4.0, SD 0.85). Aquaculture farming was deemed most feasible to co-exist with fixed offshore wind farms (means 3.93–4.19), while floating wind farms were felt to be more co-locatable with fishing practices (means 3.94–4.06) and carbon capture storage devices (mean 3.87) compared to fixed structures. Recommendations are suggested for future policy development and scientific research in relation to the application of Marine Net Gain assessment for offshore wind farm projects.