Scottish Marine and Freshwater Science Vol 11 No 11

Offshore renewables have the potential to make a significant contribution to the Scottish Government’s target to generate 50% of Scotland's overall energy consumption from renewable sources by 2030 and to have decarbonised the energy system almost completely by 2050. The offshore wind industry is set to expand substantially in Scotland and the rest of the UK over the next decade and beyond as both the Scottish and UK Governments strive for clean energy and climate change targets, and a green economic recovery. However, the Scottish Government has a duty to ensure that offshore renewable developments (ORDs) are achieved in a sustainable manner, by protecting habitats and species from adverse impacts.

Noise from offshore renewables, particularly in the construction phase, can disturb marine mammal species and the potential impact of any new development requires assessment. The interim Population Consequence of Disturbance (iPCoD) is a framework that allows individual-level effects from disturbance to be scaled to population-level impacts. However, the iPCoD framework relies on expert elicitation, which is a source of variability and uncertainty in outputs. Another approach, which has the potential to be integrated into the iPCoD model, is Dynamic Energy Budgets (DEBs) theory. Incorporation of DEB theory into the modelling process can be used to predict how behavioural and environmental changes (e.g. food availability) influence individual energy budgets and thus population vital rates. Consequently, DEBs have the potential to produce a more accurate and robust prediction of population-level impacts.

This report has developed dynamic energy budget (DEB) models for harbour porpoise, bottlenose dolphins, minke whales, harbour seals and grey seals in the UK based on values from current literature. It illustrates how a DEB model can be used to investigate the potential effects of disturbance that cause a reduction in energy intake, subsequently effecting vital rates (individual survival and birth rate), using harbour porpoise as an example. The report also highlights limitations in current knowledge and next steps in research to progress the DEB approach for these species and others.

This work represents a significant step towards a more empirical framework for marine mammal assessments to reduce uncertainty and, while some expert elicitation will still be necessary due to gaps in empirical knowledge, these models can provide a more detailed and robust assessment of population-level consequences of impact that will aid interpretation by advisors and decision makers.

The project was funded by Scottish Government (Marine Policy and Planning) as part of the Scottish Marine Energy Research programme and undertaken by SMRU Consulting.