Examining the human-predator interface of the North Sea : interactions between offshore energy structures, commercial fisheries and marine predators

The North Sea is one of the world’s most heavily exploited and industrialised shelf seas, supporting extensive offshore energy infrastructure, including oil and gas (O&G) platforms and offshore wind farms (OWFs), alongside intense commercial fishing activity. Despite this high level of anthropogenic pressure, the region continues to support populations of marine predators such as grey (Halichoerus grypus) and harbour (Phoca vitulina) seals. The North Sea is currently undergoing a period of rapid transition, characterised by the decline and decommissioning of O&G infrastructure and the simultaneous expansion of OWFs, resulting in substantial changes to the distribution and density of offshore energy structures (OES). However, the extent to which commercial fisheries and marine predators interact with OES, and the ecological consequences of these interactions, remain poorly understood. This thesis examined the spatial and ecological interactions between OES, commercial fisheries, and marine predators in the North Sea, with a particular focus on grey and harbour seals. To address this knowledge gap, spatial datasets describing the distribution of OES were integrated with spatial GPS fisheries locations and movement data from GPS-tagged seals. These datasets were combined to quantify spatial overlap, assess interaction patterns, and evaluate differences among OES types. Results indicated that, overall, spatial overlap and interactions between commercial fisheries, tagged seal individuals, and OES were relatively low. Amongst the different OES types, fixed O&G platforms exhibited the highest levels of interaction with both fishing vessels and seals, compared with other types of OES. These findings provide new insights into how marine predators and fisheries utilise space within a highly industrialised marine environment. By quantifying these interactions, this thesis advances understanding of ecosystem dynamics in the North Sea and during. The results are relevant to a broad range of stakeholders, including ecologists, engineers, policymakers, industry advisors, and geoscientists, and will informing effective and sustainable policy decisions. In particular, the findings provide an evidence base to inform decommissioning decisions, including ongoing discussions surrounding the OSPAR 98/3 regulation, and contribute to the development of effective, ecosystem-based management strategies for the future of the North Sea.