Abstract
The offshore wind industry is in the process of a significant expansion with a move towards clean energy and a green economic recovery. The sustainable expansion of offshore wind requires a robust understanding of the impacts of construction and operation and appropriate levels of conservatism and realism in assessments. The potential risk of injury and/or disturbance to marine mammals during construction of offshore renewable energy developments (e.g., pile driving, removal of unexploded ordnance, increased vessel presence offshore) has been identified as a key consenting risk for projects in UK waters. Possible consequences of exposure to underwater noise include disturbance that could cause marine mammals to either move away or change behaviour (which could result in reduced net energy intake) or suffer temporary and permanent hearing damage. The scale of offshore wind farm developments means there is the potential for significant cumulative impacts on marine mammals, which would need to be considered and mitigated at a project and regional level. The interim framework for assessing the Population Consequences of Disturbance (iPCoD) relies on the relationship between the disturbance experienced by an animal and how that disturbance impacts vital rates such as the probability of surviving to the next year or the chance of giving birth to a viable pup or calf. The relationships used in iPCoD were obtained from formal expert elicitation approaches (EE). The iPCoD tool has been updated with new elicitations and other improvements in recent years (including updated elicitations). Despite these model updates, the reliance on expert judgement is a source of uncertainty in assessments and risk for decision makers (as it relies on the carefully solicited judgments of experts rather than empirical datasets). Disturbance can cause behavioural, physiological and health changes which can have subsequent effects on an individual’s vital rates, such as survival and reproduction. The cost of disturbance is in most cases mediated by the state of the individual (e.g., life history stage and exposure history) and the environment that the individual is in (e.g., resource availability). By modelling health, we have an explicit scalar link between individual health, response to disturbance and the consequential population demographic effects of this disturbance. A wide range of bioenergetic models exist for marine mammal species and other taxa, and the principles behind these models are well established. The overall objective of this project was to describe Dynamic Energy Budget (DEB) frameworks for harbour seal (Phoca vitulina), grey seal (Halichoerus grypus), bottlenose dolphin (Tursiops truncatus) and minke whale (Balaenoptera acutorostrata) (building on an existing DEB model for harbour porpoise (Phocoena phocoena)) to help improve marine mammal assessments for offshore renewable developments.