Marine mammal bycatch in southwest England: Taking a holistic approach to assess causes, impacts and evidence-based solutions

The widespread and pervasive nature of plastic pollution has resulted in a growing body of evidence documenting the detrimental effects of anthropogenic waste on marine organisms. Over the last two decades, the number of marine species known to be impacted by debris, the majority of which is plastic, has more than trebled. Of particular concern are the marine megafauna, namely marine mammals (e.g. cetaceans and pinnipeds), elasmobranchs (sharks and rays), and marine turtles. These large marine vertebrates play key roles in the functioning and maintenance of marine habitats and are often considered indicators of marine ecosystem health. Plastic ingestion by marine megafauna can lead to a range of lethal and sub-lethal impacts, including intestinal blockage and internal injury, dietary dilution, malnutrition, exposure to chemical contaminants and increased vulnerability to disease. This project builds on previous research undertaken by the supervisory team from the University of Exeter, Plymouth Marine Laboratory and the Cetacean Strandings Investigation Programme to understand the extent and potential impacts of plastic ingestion by a range of marine megafauna species, including whales, dolphins, seals, turtles, and sharks, found in UK waters. The aims are to; 1) Develop a method of sampling large marine animals collected by the UK stranding networks for evidence of plastic consumption, 2) Characterise any plastic debris within the gastrointestinal tracts of the stranded animals, with a view to identifying potential sources and informing policy, 3) Investigate the differences in exposure to plastic pollution among species, life-stages, and feeding strategies/diet, 4) Examine spatial patterns to assess species vulnerability by exploring the overlap between species distributions and habitat use with hotspots of plastic pollution and 5) Consider the adverse health impacts of plastic ingestion for individual animals as well as the potential population-level effects.