With the increasing threats of climate change, there is an ever-pressing need to reduce fossil fuel emissions. Thus, recent years have seen a dramatic increase in the development of marine renewable energy (MRE) devices – in particular tidal stream turbines (TSTs) – to exploit tidal stream environments (TSEs) for green electricity generation. However, TSTs may pose threats to marine megafauna and relatively little is known about how animals operate in the environments targeted by these devices, and how they may be affected by them. This information is crucial for informing appropriate management strategies to mitigate the risk of conflict between animals and TST developments. Here, using grey seals (Halichoerus grypus) and harbour seals (Phoca vitulina) as my study species, with data collected from around the UK and neighbouring waters, including the Celtic and the North Sea, I aim to understand and quantify how seals move in TSEs and the implications of this for the TST industry. To achieve this, I quantify the broad-scale movement patterns of seals in coastal waters and their overlap with TSTs, examine the fine-scale movement and behaviour of seals in response to tidal conditions, derive recommendations on sample size and recording duration for animal tracking studies, and design new tags to track seals in TSEs at very fine-scales whilst minimising tag impact. My results suggest that the movements and behaviour of seals are driven by a combination of measurable (and in some cases predictable) demographic and environmental factors, and that the conservation strategies developed to manage the interaction between individuals and populations with TST devices must consider site-specific differences and account for individual variation, with consequences regarding data requirements. Further investigation is required to fully elucidate the extent of variability of seal movements in TSEs and the threats of TST developments, however the research presented herein provides new tools and ecological insights to support this need for both researchers and practitioners.
The persistence in time of distributional patterns in marine megafauna impacts zonal conservation strategies
